lal Bureau of Standarfls

y, E-01 Admin. Bldg.

4 B68

BUILDING SCIENCE SERIES

175130

Reference book noiio do

taken Um the iibrer

8

OCT 1 ? 1975

Interrelations

Between

Cement & Concrete

Properties

PART

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards
Announcing —The Building Science Series

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UNITED STATES DEPARTMENT OF COMMERCE

C. R. Smith, Secretary

NATIONAL BUREAU OF STANDARDS • A. V. Astin, Director

Interrelations Between Cement and

Concrete Properties, Part 3

Compressive Strengths of Portland Cement

Test Mortars and Steam-Cured Mortars

R. L. Blaine, H. T. Arni, and M. R. DeFore

Building Research Division

Institute for Applied Technology

National Bureau of Standards Washington, D.C. 20234

Building Science Series 8

Issued April 1968

For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 - Price 55 cents

I
RELATED PUBLICATIONS

NBS Monograph 28—Causes of Variation in Chemical Analyses

and Physical Tests of Portland Cement—25 cents*

NBS Monograph 43—Chemistry of Cement Proceedings of the

Fourth International Symposium—Washington 1960. Presented

m two volumes. Volume I—$6.50. Volume II—$6.25. The two

volumes at $12.75 a set. (Originally issued September 1962, and

reprinted February 1964.)

NBS Building Science Series 2 and 5—Interrelations between

Cement and Concrete Properties. Part 1 —35 cents. Section 1, Materials and Techniques. Section 2, Water Requirements of Portland Cement. Section 3, Occurrence of Minor and Trace Elements in Portland Cement. Part 2—35 cents. Section 4, Variables

associated with expansion in the potential sulfate expansion test. Section 5, Heat of hydration of portland cement. Section 6, Variables associated with small autoclave expansion values of Portland cements.

*Order publications from Superintendent of Documents, Government Printing

Office, Washington, D.C. 20402. (For foreign mailing, add one-fourth of the

price of the publication.)

Library of Congress Catalog Card Number : 64-60095

II
Contents

Page

Section 7. Compressive strength of test mortars 1 R. L. Blaine, H. T. Arni. and M. R. DeFore

Section 8. Compressive strength of steam-cured portland cement

mortars 67

R. L. Blame, H. T. Arni, and M. R. DeFore

Section 7. Compressive Strength of Test Mortars

R. L. Blaine, H. T. Arni, and M. R. DeFore

The relationships between cement characteristics and compressive strength of 1:2.75 (cement to graded Ottawa sand) mortars of standard consistency at ages of 24 hours to 10

years, and made with 199 cements of different types, were studied by fitting multivariable

regression equations with the aid of a digital computer. The dominant variables associated with the differences of compressive strength, strength gain, and strength ratios wore different at the various test ages, and after different curing conditions. The additional use of certain

trace elements with commonly determined independent variables resulted in a significantly better fit between the equations and the observed data. Interactions between the fineness values and othei;- independent variables were noted. Certain parallelisms and differences were noted with respect to variables associated with compressive strength differences at various ages and the heat of hydration of the cements at these ages. Key Words: Chemical composition, fineness, heat of hydration, strength gain of Portland cements, trace elements. CONTENTS

Page

1. Introduction 1

2. Materials 2

3. Tests and nomenclature 2

4. Statistical studies 2

5. Results of tests

5.1. Compressive strengths of mortars of differ- ent types of cement 3

5.2. Compressive strength at 24 hours 4

5.3. Three-day compressive strength 7

5.4. Seven-day compressive strength 7

5.5. Twenty-eight day compressive strength 8

5.6. Compressive strength of water-stored speci- mens at 1 year 9

5.7. Compressive strength at 1 year after moistair storage 13

5.8. Compressive strength at 1 year of laboratory-air-stored specimens 19

5.9. Compressive strength at 5 years of waterstored specimens 19

5.10. Compressive strength at 10 years of waterstored specimens 23

5.11. Gain in compressive strength between 7 and

28 days 24

5.12. Compressive strength-gain ratio, (28 day-7

day)/7 day, or SGR(l) 27

5.13. Compressive strength gain from 7 days to 1 year 30

5.14. Compressive-strength-gain ratio, (1 year-7

day)/7 day, (SGR(2)), for water-stored specimens 31

5.15. Compressive strength gain from 28 days to lyear(SG(3)) 32

Page

5.16. Compressive-strength-gain ratio, (1 year- 28 day)/28 day, (SGR(3)), for specimens

stored in water 37

5.17. Compressive strength gain from 28 days to 10 years 39

5.18. Compressive-strength-gain ratio from 28 days to 10 years, (STXY-ST28)/ST28_ _ . 42

5.19. Compressive-strength ratio of 1-year (waterstored/moist-air-stored) specimens 45

5.20. Compressive-strength ratio of 1-year (air- stored) to 28-day, water-stored specimens. 50

6. Discussion

6.1. Compressive strength of different types of cement 53

6.2. Relationships of compressive strengths de- termined at different ages 53

6.3. Early strength versus composition of the ce- ment, and the prediction of strength at

later ages 57

6.4. Coefficients, and their significance, of the major potential compounds, of other commonly determined variables and of the trace elements at different test ages— 57

6.5. - Coefficients, and their significance, of the major oxides at different test ages 60

6.6. The effect of alkalies in portland cement on

compressive strength 60

6.7. Compressive strength and heat of hydration. 60

6.8. Air permeability and turbidimeter fineness values and compressive strength 61

6.9. Compressive strength and other independent

variables 62

7. Summary and conclusions 62

8. References 65

1. Introduction

Compressive strength tests of 1:2.75 (cement to graded Ottawa sand) mortar cubes are required

in Federal [1] ' and ASTM [2] specifications for Portland cements. These plastic mortar tests were

adopted in 1936 after considerable study, as a means for evaluating the strength producing

properties of different portland cements. Although

the test-mortar cannot be used to predict the

strength characteristics of any and all concretes,

it is considered indicative, to a limited extent, of

' Figures in brackets indicate the literature references at the end of this

section, p.65.

the relative concrete strengths which may be

obtained if other potential variables are held

constant. These specification tests are usually made at early ages, for example, 1 and 3 days, 3 and 7days,

or occasionally at 7 and 28 days. The values

obtained, together wdth knowledge of the chemical

composition of the cements, are used, to some

extent, to predict the potential strength, or the

strength at later ages of mortars or concretes made

from these cements. Lack of complete information on the variables associated mth gain in com1
pressive strength with time of hydration results

in difficulties in predicting the potential compressive strength. Tests have been reported on the

strengths and strength-gain characteristics of laboratory prepared major compounds potentially

present in cement, both separately, [3, 4] and in various combinations. Tests have also been made

of the effect of some of the minor constituents [5]. Numerous authors ^ have pubUshed the results

of strength tests, and the increase of strength with

age of both mortars and concretes [6]. Statistical

techniques have been used to derive factors for the contributions of the major components. However, it has been reported that results obtained

from different sets of data vary widely. Some of the limitations and uncertainties of the statistical approach to the study of factors contributing to the strengths of cements have also been discussed

[7]. Mentioned among these limitations of previous

studies was the lack of information on the kind

and amount of the minor constituents and trace elements. The present statistical analysis includes

the study of the effects of the trace elements as well as other components among the variables

associated with compressive strength values of mortar cubes at ages up to 10 years.

2. Materials

The Portland cements used in this study have

previously been described [8, 9, 10]. Briefly, they

consisted of 199 commercially manufactured

cements of the different types, and were obtained

from different areas of the USA, with a few

obtained from other countries. These cements

were classified primarily on the basis of their

chemical analyses and physical tests, and included

82 Type I, 68 Type II, 20 Type III, 3 Type IV,

and 12 Type V cements. Also included were 14 air-entraining cements. The chemical analyses and

other tests indicated a fairly broad range of properties.

3. Tests and Nomenclature

Mortars for two-inch plastic mortar cubes were

proportioned, mixed, and compacted in accordance

with Federal [11] and ASTM [12] specifications

except that the amount of water required for a percentage flow of 110 ±5 was used. Three 9-cube

batches of the 1 : 2.75 (cement to graded Ottawa

sand) mortar were made with each of the cements.

Although most of the cements were tested in the

Washington laboratory, many were tested at the

field stations in AUentown, Denver, San Francisco,

and Seattle. Three cubes were tested in compression at each

age, and after each of the various storage conditions. After the first 22 to 24 hr in the molds in

the moist cabinet at 95 to 100 percent relative

humidity, most of the specimens were stored in water and tested at the ages of 24 hr, 3, 7, and 28

days, 1, 5, and 10 years. In this section of this

series, these will be designated as STOl, ST03,

ST07, ST28, STlY, ST5Y, and STXY respectively.

Three specimens made with each cement were

stored continuously in the moist cabinet at 95 to 100 percent relative humidity and tested at 1 year. These were designated as STlM. The other

3 specimens were stored in water for 6 days, then

in laboratory air at 50 ± 5 percent relative humidity

for 49 weeks, then in water for 2 weeks and then

tested in compression. These specimens were

designated STlA.

In addition to using the value of the strength at various ages and conditions as dependent variables, the foUowing calculated variables were used:

ratios between two strengths, strength gains ex- pressed as the difference between two strengths,

and strength gains expressed as the ratio of the

difference between two strengths to the earlier strengths. The various measured and calculated

dependent variables are identified by symbols as follows

:

SR(1) for STlY/STlM

SR(2) for ST1A/ST28

SG(1) for ST28-ST07

SGIl(l) for (ST28-ST07)/ST07

SG(2) for ST1Y-ST07

SGR(2) for (STlY-ST07)/ST07

SG(3) for ST1Y-ST28

SGR(3) for (STlY-ST28)/ST28

SG(4) for STXY-ST28

SGR(4) for (STXY-ST28)/ST28

Other nomenclatm-e used in this section is consistent with that used in previous sections of

this series.^

4. Statistical Studies

The statistical techniques used to determine the

independent variables associated with the strength

values at the different ages, the increase in

strength at the later ages, and the strength ratios

at different ages have been described in a previous

- Compressive strengths of portland cement mortars and concretes have

been the subject of so many investigations during the past century that it would not be practical or possible to list them all.

section in this series of articles [8]. These techniques included plots of the dependent and major

' Among the abbreviations or symbols used are C3A, C3S, C2S, and CiAF

for the calculated potential compounds, tricalcium aluminate, tricalcium

silicate, dicalcium silicate, and tetracalcium aluminoferrite respectively. Also used are AE+NAE for air-entraining plus nonair-entraining cements, NAE for nonair-entraining cements, APF for air permeability fineness, WAGN for Wagner turbidimeter fineness. Loss for loss on ignitions, and Insol.

for insoluble residue.

2
independent variables as well as the use of the

"tic-tac-toe," and the Students "t" test, of the

"hi-lo" and "middle-ends" comparisons to determine which of the minor constituents or trace elements were probable contributing factors to

variations.*

Multiple regression equations were calculated

by the least squares method and were considered

of greatest significance in drawing conclusions.

As in previous sections, comparisons were made of the degree of fit using only commonly determined

variables, and these together with minor and trace elements. The level of significance of any reduction

in the S.D. values resulting from the use of the

additional variables in the equation was calculated

for various pairs of equations or for the S.D.

values of the property of the cements (as presented

in footnotes in the tables) compared with the S.D.

values of an equation fitted with independent

variables. The reduction in variance for different

pairs of equations and critical "F" values which

must be exceeded for significance at the five- and

one-percent probability levels are presented in a

table summarizing these calculations. Equations were obtained using the major potential compounds as well as the major oxides. Equations were calculated for both the AE+NAE cements

and for the NAE cements for all of the dependent

variables.

After it had been determined which of the independent variables were significantly ^ associated

with the dependent variable when used in an

equation, the residuals of the equation were fitted by a least squares method to other single independent variables and the reduction in variance

calculated. If any of the additional independent

variables indicated a significant reduction in vari- ance, they were tried in the equation and retained

if the coef./s.d. ratio was greater than one. Equations were also computed for the "odds"

and "evens" in the array of cements. Comparisons

were made of the coefficients of the variables in

the two lots of cements and these were compared

to the coefficients and coef./s.d. ratios computed

f or all the cements.

5. Results

5.1. Compressive Strengths of Mortars of Different Types of Cement

Presented in figure 7-1 are plots on a semilog

scale of the average compressive strength values

of the mortars made from the different types of cement versus the age at which the specimens were tested. None of the AE cements were included

in these averages. All of the specimens were

* statistical terms and notations employed in this section are the same as those of previous sections in this series of articles. For example, S.D. refers to the estimated standard deviation calculated from the residuals of a fitted equation, or the estimated standard deviation about the average. Also, as

in previous sections, s.d. refers to the estimated standard deviation of a

coefficient of an independent variable used in a fitted equation, coef./s.d. the

ratio of the estimated coefficient (of an independent variable used in an

equation) to its estimated standard deviation and "F"=Fisher's ratio of variances.

In calculating the equations, there was a choice

in the fineness values of those determined by means

of the air-permeability method and those determined by the Wagner turbidimeter method. Calculations were made using the fineness values as obtained by each of the methods. Although the

results obtained by the two methods are closely

related, the ratios of the values obtained by the

two methods may differ appreciably. Variables

associated with these differences are presented in the discussion.

No measurements were made of the quantity

of air entrained in the 1 :2.75 mortars. It was

therefore necessary to use the air-content values

in the 1 :4 (cement to 20-30 Ottawa sand) mortars

as an independent variable even though the rela- tion between the entrained air in the 2 mortars is far from perfect.

Although compressive strength tests were made

on all 199 cements, the calculations of the equations presented in this section were limited to those

for which trace-element determinations had been

made. The 3 white cements and the cement having

a high autoclave expansion were excluded, as were

also a few other cements that had large deviations

from the calculated relationships for no apparent

reason. The frequency distributions as well as the

calculated contribution of the various independent

variables included all the cements for which values were available.

Equations presented in this article were selected

from a large number of trial equations indicating

the relationship of various independent variables

to the compressive strength values ^ at each of the test ages, to the strength gain at different

ages, and to the strength ratios of specimens

tested at different ages of after different curing

conditions. The differences and trends indicated

by these series of equations will be treated in the

discussion in subsection 6. Some of the limitations on interpretations of multiple regression equations,

as well as other statistical techniques used in this

this series of articles, have been discussed in section 1, subsections 4.2, 4.3, and 5. [8].

Tests

stored in water after the first 24 hr in the molds

in the moist cabinet. The average compressive

strength values of the 1 year air-stored specimens,

(STlA), (not indicated in this figure) were about

the same as the averages of the 28 day water

stored specimens, (ST28). The 1 year moist-airstored specimens (STlM) had average compressive

strength values close to those stored in water for

« As previously indicated [8], a coef./s.d. ratio greater than one was considered to be of sufficient significance to warrant further investigation.

6 The equations may be interpreted as indicating the independent variables associated with tlic compressive strength, per se, or, what appears more plausible, the independent variables associated with differences in compressive strengths of different cements. This interpretation assumes

that Portland cements have certain inherent strength-producing properties

resulting from chemical, and manufacturing, as well as specification requirements.

3
I Type I,

28 D I Y 5 Y 10 Y

AGE, DAYS (D) AND YEARS (Y)

. Type II, O Type III, and A Types IV, V Figure 7-1. Results of plotting average compressive strength

at the various test ages of nonair-entraining cements of

the different types.

1 year (STlY). These strength ratios will be

considered in a later subsection. The cements

classified as Types IV and V had an average

compressive strength lower than that for the

other types at ages up to 28 days but had the

highest average at 1, 5, and 10 years. The averages

of those classified as Type I cements had the

lowest average compressive strength after 1 year

or longer. The averages of all of the types of cement appear somewhat lower at the 10 year

test age than when tested at the age of 1 year. This decrease did not occur for every cement

within each group.

5.2. Compressive Strength at 24 Hours

The frequency distributions of the 24-hr compressive strength values obtained with the cements

are presented in table 7-1. Each of the types of cement, as classified/ had a range of strength

' As previously indicated, [8], the cements were classified primarily on the

basis of the chemical analysis and physical tests such as air-entrainment,

fineness, etc. Table 7-1. Frequency distribution of cements with respect

to 1-day compressive strength in psi of 1:2.76 {cement to graded Ottawa sand) mortar cubes

Compressive strength, psi X 10-' Type cement 0to 0.3

0.3

to 0.6

0.6

to 0.9

0.9

to 1.2

1.2

to 1.5

1.5

to

1.8

1.8

to 2.1

2.1

to 2.4

2.4

to 2.7

2.7

to 3.0

3.0

to 3.3

Tdtal

Number of cements

I 1 2 37

8

35 5 2 82 lA 8

II

"7 33 26 2 68 IIA 1 1 1 3 m.. 2 8 3 3 1 1 20 IIIA 2 1 3 IV& V 2 8 6 15 Total 1 11 87 67 10 12 3 3 3 1 1 199

I—I OJ O i-H

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- . .

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r^coJ^JgajooGOTf* 100 100 tPo oo 00 00 00 4--+ -1-^+-'

CM;lJt--OS OSO OlOOoo'^ Cl^COGO OOMCOt^OCOcOOT

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+ + + + + + + + + + + +

if2t^ '^fS "^-^ oscoMoo iNqo

°;QOor^ Ooo i>-TtH cioo t-tco

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t-~. O ^ CO O ^ ^ V t>.'^eoi>- t-w c^ososw oco

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+ +

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II II II II II II II II

II II II II II II II II II

II

II II II II II II

o .0 .0 ,0 • ^ ' ^ . ' '~' .0 .0 .0 . f:^ -a fri -a -a ^ -a f-i'O tr^^o fr''0 ^ 'a ^"zs f-i-o (r^ -a {-I "O

< m

4
DEPENDENT

VARIABLE —

INDEPENDENT VARIABLES

COMPRESSIVE

STRENGTH

S| 02 AljOj FejOj SOj NajO KjO TOTAL A S AIR P. WAON. AIR AGE NOTE * CaO MgO

ALKALI CjA C3S C2S C4AFF A + F FINE FINE 1:4 IWRt

1 DAY

'

(STOI)

(11

(2)

(3)

(4)

9

3 IV.

NL

-10

7

5

NO

-3

8

4 kNL

-II

102 kNL + 176

6

1 NO

+ 1

102

L +13

102

IV

N L -5

GG

NO

+ 8

G

G

NO

- 1

84

NO

+4

102 1/

L + 13

102 kL -137

5 kNL

-10

8

4 kNL

+13

84 kNO-284

NO

+4

84 K

NL

+ 9

8

4

NO

-3

3 DAYS (ST0 3 )

(1)

(2)

(3)

(4)

102

NL

-18

8

4

1 /

L?

+ 9

84 kNL-9

102 1/

L

+13

6

G

NO-5

102 kL

+17

8

4 IV,

NL-9

6

G

NO

+ 3

6

G

NO

-1

9

3

L? +8

102 kNL

+ 17

102 kNL

-19

102 k

NL

-15

102

L? + 11

8

4 l-N

L? -8

G

6 kNL+7

6

6 kNL +4

6

e

NO-3

« * *

7 DAYS

(ST07 )

(1)

(2)

102 IV102120 k102 k93 t\84G

6

8484102

11^y

102 k120 N120 k

120 1/

84

7

5 k

84 k66

(3) (4) NL

-19

L?

418 NL

-24

L +15 L?

- 8

L +12 NO -3NO

+ 1 NO-2

NL + 19 NL + 18 L -24

NL

-24

L? +24L?-6NL

+10 NL + 7 NO

-4

28 DAYS* *

*

1ST 28)

(1)

12)

S4 t\

6.6

6

6

120

1

8.4

1L

S.G 4102102 LA

7

5

1

1

102

1K

102 6

6 6

6

S

4 tk

8

4

102 L_

84 tV

(3)

14) L?

-II NO

H5 NO-4

NL

+ 17 NO

-6

NO

+2 NO

-3

L?-6L

-11 NO

+ 2 NL+19 NL

-16 NO

-8

NO

+8

L?

-11 NL

+ 9 NL

+ 11 NL

-12

Figure 7-2. Results of plotting compressive strength values at 1, 3, 7 and 28 days of 1:2.75 {cement to graded Ottawa sand) mortars on the "Y" axis versus various independent variables on the "X." axis.

*Note (1) Ratio of number of plotted points in paii s of diametrically opposite quadrants. Note (2) General trend of lines drawn through plotted points. Note (3) Apparent nature of relationship. L=linear; NL=nonlinear; NO=no apparent relationship; and L?=nature of relationship not determinable. Note (4) Quadrant sum in corner test. (See reference [8].)

* *Moist-air-stored. ***Stored in moist air 24 hours then in water.

values, and there was considerable overlapping of the values obtained with the different types.

The results of the preliminary plots of the 1-day

compressive strength values versus various independent variables are presented in figure 7-2.

The lines drawn through the 12 pairs of averages

to indicate the trend, and the significance of the

number of points in the opposite quadrants as well as the "quadrant-sum" have previously been

discussed in section 1, subsections 4.1 and 5 [8]. It may be noted that at 1 day, Fe203, CaO, SO3,

C3S, C2S, and A/F all had quadrant-sum values

greater than 11, a value which may be considered

significant at the five percent confidence level. Selected equations relating the 24-hr compressive strength values of the AE + NAE cements

to various independent variables are presented

in table 7-2. Equation 1 presents the relationships

found for commonly determined independent

variables. The use of C2S in addition to the C3S,

or the use of the C3S/C2S ratio, did not result in a lower S.D. value.

Using the statistical techniques previously

described it was determined that of the other

variables, only SrO, Ni, and P had coef./s.d.

ratios greater than one. The relationship is presented in eq 2. The S.D. value was lower than

in eq 1 and by reference to table 7-75 ^ it may be

* A tabulation of the reduction in variance, "F" values, for all equations

cornpared is presented in table 7-75. Presented also are the critical values for "F" which must be exceeded for significance at the one and five percent levels

for the number of degrees of freedom (D.F.) involved in each comparison.

noted that the reduction in variance was significant at the one percent probability level. Equations 2A and 2B, calculated with the

"odds" and"evens" in the array of cements,

indicated uncertainties with respect to the coefficients for insoluble residue, SrO, and Ni.

None of these three variables were highly significant in eq 2 where the larger group of cements

wei'e used in the calculations. The coefficients of other variables also differed but not so much that

the coef./s.d. ratio was less than 1. Reasons for such variations have previously been discussed in earlier sections of this series of articles [9].^ When using the fineness values obtained by

means of the Wagner turbidimeter method instead

of those obtained by the air-permeability method,

it was necessary to delete Loss (which then had a

coef./s.d. ratio less than 1) , and to include C4AF as an independent variable in order to obtain S.D.

values in eqs 3 and 4 comparable to those in eqs 1 and 2. The series of eqs 5 through 8 were computed

with the use of the major oxides instead of the

potential C3S and C4AF compounds. All of the

major oxides had significant coef./s.d. ratios. The

9 If a number of cements having higher than normal values for an indepen- dent variable are included in one of the two groups (the "odds ' or "evens") by the arbitrary division of the cements, spurious coefficients may be obtained

for this variable. The estimated standard deviations of the coefficients of the smaller groups were usually larger than when a combination of the "odds"

or "evens" in the array of cements were used in calculating the equations. If

tlie coefficients of both the "odds" and "evens" of an independent variable

are significant, a greater confidence can be placed in the equations and in the

association of that independent variable with the dependent variable.

5
o

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use of the turbidimetric fineness values, as in eqs

7 and 8, resulted in the change in the significance

(coef./s.d. ratio), of the Loss. (The interdependence

of some of the so-called independent variables will be treated in the discussion.)

A comparable series of equations computed for the NAE cements are presented in table 7-3. The

coefficients of the independent variables are in reasonable agreement \vith those presented in

table 7-2, except that the "air, 1:4 mortars" had

a somewhat lower coef./s.d. ratio. The increase in SrO and P appeared associated with lower 24-hr

compressive strength,- whereas an increase in Ni

appeared associated with higher strength. In

general the coefficients of the SrO and P were

significant but those for Ni were questionable.

Comparing the S.D. values of eqs 1 and 2, 3 and

4, 5 and 6, or 7 and 8 indicate that the use of the

trace elements resulted in a significant reduction

in the S.D. values.

Using the independent variables and their coefficients of eq 2, table 7-2, and the ranges of these variables, values were calculated for their

contributions, and ranges of contribution to the

24-hr compressive strength. These calculated

values, as presented in table 7-4, are approximations based on a single equation, and it may be

noted that somewhat different values may be

obtained by use of other equations.'"

Table 7-4. Calculated contribution of independent variables

to 1-day compressive strength in psi of 1:2.75 {cement to graded Ottawa sand) mortar cubes, moist-air-stored, and

the calculated ranges of such contributions

Coeffi- Calcu- Range of cients Calculated lated Independent variable from eq contribution range of variable (percent) 2 of table to STOl contri- 7-2 bution

to STOl

Const. = -2073 C3S 20 to 65 +19.0 +380 to +1235 855 SO3 1. 2 to 3.

0

+259 +311 to +777 466 Loss 0. 3 to 3.

3

-186 -56 to -614 558 Insol 0 to 1.

0

-163 Oto -163 163 APF. »2500 to 5500 +0. 541 +1352 to +2976 1624

Air, 1:4 mortar 1 to 21 -15.5 -16 to -326 310 K2O 0 to 1.

1

+375 Oto +412 412 SrO 0 to 0.

4

-359 Oto -144 144 Ni" 0 to 0. 02 +5450 Oto +109 109 P 0 to 0.

5

-282 Oto -141 141

*cmVg.

**Doubtful significance. Coef/s.d. less than 2. Although the C3S and the fineness were the

principal contributors to the 24-hi compressive

strength, the increase in SO3 was associated with

higher strength values as were K2O and possibly

Ni of the minor constituents. Increase in Loss,

insoluble residue, and SrO were associated with

lower strengths. In this and in corresponding

tables throughout this paper, coefficients for which the coef./s.d. ratio is less than 2 (indicating

10 Computations for contributions to compressive strengths at other ages

will also be made from similar equations, i.e. , one selected from the AE+NAE

cements containing one or more of the potential major compounds, and using air-permeabihty fineness values in order that trends may be more easily followed.
only possible significance) are identified by a double asterisk.

5.3. Three-Day Compressive Strength

The frequency distributions of the 3-day compressive strength values for the different types of cement are presented in table 7-5. There was a

considerable spread of values with each of the

types, and an overlapping of values for the

different types of cement.

The preliminary plots and trends of the relationships to various individual independent variables

are presented in figiu-e 7-2. Si02, CaO, SO3, C3S,

Table 7-5. Frequency distribution of cements with respect

to 3-day compressive strength 0} 1:2.75 {cement to graded Ottawa sand) mortar cubes, water-stored

Compressive strength, psiXlO-'

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 Type cement to to to to to to to to to to to Total

1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 G.O Number of cements

I 1 29 36 12 4 82

IA 4 4 8 II 9 36 21 2 68 IIA 1 2 3

Ill 1 1 5 3 6 3 1 20 IIIA 1 1 1 3 IV & V 4 9 2 15

Total 1 18 78 62 15 10 4 6 4 1 199

C2S, C4AF, and A/F all had quadrant-sums with

absolute values greater than 11. Equations selected from those computed to determine the relationships of various independent

variables with the 3-day compressive strength

values for AE +NAE cements are presented in

table 7-6. Commonly determined variables which

show relationships to the 3-day compressive

strength are presented in eq 1. The use of the trace elements SrO, Mn, Cr, and V with the commonly

determined independent variables, as in eq 2, resulted in a significant reduction in the S.D.

value although the coef./s.d. ratio for Cr was of doubtful significance. In the calculated equations

for the "odds" and "evens," eqs 2A and 2B, the

coef./s.d. ratio was less than 1 in one or the othei

of the two equations for K2O, SrO, Cr, and V.

Reasons for such discrepencies have been discussed

in previous sections. Equation 3 illustrates the

effect of using the turbidimeter-fineness values

instead of the air-permeabUity values. The loss on

ignition, highly significant in eq 2, was not signifi- cant when tiu'bidimeter results were used, and

therefore was not included in eq 3. Use of the

C3A/SO3 ratio in place of C3A as an independent

variable made no significant difference in the results (eq 3, 4, and 5). However, using the trace elements SrO, Mn, and V with C3A/SO3 as in eq 6

residted in the lowest S.D. value obtained with

this group of equations.

Equations 7 through 10 of table 7-6 were cal- culated using the major oxides, and resulted in S.D. values similar to those obtained with the

major potential compounds in eqs 1 through 6. However, the use of the trace elements resulted

in reduction of variance which was significant at the five percent level for eqs (7) and (8), and at the one percent level for eqs 9 and 10. (See table

7-75.)_

A similar series of equations computed for the

NAE cements are presented in table 7-7. Comparing eqs 1 and 2, 4 and 5, or 8 and 9 indicates that

the use of the trace elements resulted in lower S.D.

vakies significant at the one percent probability

level, whereas in comparing eqs 6 and 7 the reduction of variance resulting from the use of the added

independent variables was significant at the five percent level. (See table 7-75.) The K2O and Cr

had coef./s.d. ratios less than one as did Fe203 and

SO3 in one or the other of the equations for the

"odds" and "evens" eqs 2A, 2B, 7A and 7B.

Contributions and the ranges of these contributions to the 3-day compressive strength, as cal- culated from one of the equations, eq 2, table 7-6, are presented in table 7-8. Increases in fineness,

C3S, C3A, and SO3 were associated with increasing

or higher compressive strength values, whereas an increase in loss on ignition was associated with

decreasing or lower strength values. Of the minor

constituents, increased K2O and V appeared asso- ciated with increased strength values, whereas,

increased SrO and Mn appeared associated mth

decreased strength values. There is very little evidence that Cr had a significant effect.

5.4. Seven-Day Compressive Strength

The frequency distributions of the 7-day

compressive strength values obtained with the

different types of cement are presented in table

7-9. A wide distribution of values was obtained

with each of the types of cement as well as some

overlapping of the values of the cements as

classified into the various types.

The results of the preliminary plots of the 7-day

compressive strength values versus individual

independent variables are given in figure 7-2. All

of the major oxides, SO3, and A/F, and the major

potential compounds had absolute "quadrantsum" values greater than 11. The computed equations relating the 7-day

compressive strength values to various independent variables are presented in table 7-10 for the AE + NAE cements, and in table 7-11 for the NAE cements. In eqs 1 and 2 are presented

the relationship to some commonly determined

variables, and in eq 3 the relationship to commonly

determined variables plus SrO. Although the

coef./s.d ratio of MgO and SrO were less than 1 in eq 3 where APF was used as a variable, both

had ratios closer to 2 in eq 4 where WAGN was

used as an independent variable. Tlie wS.D. value

in eq 3 was significantly lower than in eq 1. Comparing eqs 2 and 4, or 5 and 6, indicated that

the use of SrO in the equations did not result in a significant reduction in the S.D. values (see

table 7-75). It may be noted in table 7-10.

7
Table 7-6. Equations relating the 3-day compressive strengths

Equation Note Const. C3S C3A CaO Si02 AI2O3 FezOs

2...

2A

2B

3-.

4_..

5__.

6__

7...

8__.

8A.

8B_

9__.

10__

(')

(1)

(=)

(^)

(')

(')

(')

(')

(1)

(')

(=)

(')

(')

(•)

ST03

s.d. ST03

s.d. ST03 (odd)

s.d. ST03(even)

s.d. ST03

s.d. ST03

s.d. ST03

s.d. ST03

s.d. ST03

s.d. ST03

s.d. ST03 (odd) = s.d. ST03(even) = s.d. ST03

s.d. ST03

s.d.

= -2950 = (250) = -3048 = (261) = -3110

= (315) = -2637

= (421)

= -3940

= (270)

= -4618

= (480)

= -4256

= (286)

= -4448

= (295)

= -8500

= (2559)

= -5721

= (2631)

= -5551

= (3257)

= -4092

= (4255)

= -9248

= (2249)

= -7981

= (2356)

+41. 51

(4. 45)

+38. 50

(4. 38)

+35. 98

(5. 04)

+40. 25

(7. 82)

+43. 32

(4. 12)

+40. 15

(4. 50) +41.71

(4. 18) +39.04

(4. 12)

+22. 05

(9. 78)

+43. 12

(10.98)

+48. 80

(12. 99) +34.38

(18. 01)

+41. 83

(9. 87) *-53. 27

(56. 71)

+215.

3

(28. 4)

+180.

8

(29. 6)

+167. 7

(34. 5)

+178.

8

(51. 4) +224.5

(26. 5)

+192. 7

(27. 7)

-229.9

(48.7)

-257. 5

(48.3)

-238. 6

(58. 9) -297.1

(81.3)

-258. 7

(42. 0)

-264.0

(43. 2)

-153.7

(56. 4) -113.8

(56. 8) -85.1

(73. 5) -154.9

(92. 5) -119.3

(51.4) -200.6

(130. 4)

-78. 88

(42. 56)

-104. 55

(42. 09) -120.4

(58. 2) -78.29

(64. 47) -101.4

(40. 1) -122.7

(39.4)

I 176 cements; Avg = 2166; S.D. =702. 5. "- 88 cements. *Coef./s.d. ratio less than 1.

eqs 5 and 6, that the coefficients for Loss and

MgO are positive, whereas they were negative in

eqs 2, 3, and 4. Trace elements, other than those

indicated in table 7-10, when tried, did not have

coef./s.d. ratios greater than 1. The comments and remarks relative to the

results presented in table 7-10 are also applicable

to the results presented in table 7-11 for the NAE

cements. The "air, 1:4 mortar" was more highly

significant in table 7-10 than in table 7-11. Equations for the "odds" and "evens" in both tables

indicated that the coef./s.d. ratios of Loss, MgO,

and SrO were less than 1 in a number of instances.

The contributions of the different independent

variables to the 7-day compressive strength were computed from eq 3 of table 7-10 and are pre- sented in table 7-12 together with the calculated

ranges of the contributions. Differences in fineness

and C3S appear to have the dominant influence on

the strength values, but differences in other variables can also result in rather large differences.

5.5. Twenty-Eight Day Compressive Strength

The frequency distributions of the 28-day comliressive strength values of the different types of cement are presented in table 7-13. Each of the

types of cement exhibit a range of values and there

is considerable overlapping of the values of the

different types.

The results of plotting the 28-day compressive

strength values of the different cements versus

various single independent variables are presented

in figure 7-2. The independent variables having

"quadrant-sum" absolute values of 11 or greater

include Si02, CaO, total alkali, C3S, C2S, S/

(A+F), and Wagner fineness and (Air, 1:4 mortar)

.

Selected equations indicating the relationships

of various combinations of independent variables

to the 28-day compressive strength values are presented in table 7-14 for the AE+NAE cements,

and in table 7-15 for the NAE cements. In eq 1 of table 7-14 are presented the relations with

commonly determined variables. C4AF had a coef./ s.d. ratio less than 1 in eq 1. This ratio was improved but stUl less than 2 in eq 4 where the trace elements and Loss were included. The S.D. value

for eq 4, however, was significantly lower than that

of eq 1. Equations 2 and 3 were computed using

the turbidimeter fineness values with a substantial

reduction in S.D. The use in eq 3 of the trace elements SrO, Cr, and Co resulted in a further

significant reduction in the S.D. value (see table

7-75). The equations for the "odds" and "evens",

eqs 3A and 3B, resulted in a positive coefficient for

C4AF in eq 3A and negative in 3B. The evidence

suggests that C4AF is not a very significant variable affecting 28 day strength.

Equations 5, 6, and 7 were calculated using the

8
m psi of AE+ NAE cements to various independent variables

Loss APF WAGN. Air 1:4 mortar

k:20 C3A

SO3

AI2O3 SO3 SrO Mn Cr V S.D,

-249.

4

(54. 9) -246.9

(53. 5) -150.3

(71. 8) -303.6

(79. 1)

+0. 7573

(0. 0706)

+0. 7890

(0. 0695)

+0. 8235

(0. 0866)

+0. 7402

(0. 1078)

-49. 55

(7. 44)

-47. 48

(7. 18) -60. 49

(10. 62)

-46. 03

(10. 20)

-47. 06

(7. 15) -46. 07

(7. 14) -46. 61

(7. 11) -44. 47

(6. 85)

-48. 06

(7. 56) -46.40

(7.41) -59. 70

(10. 99) -44. 72

(10. 57) -45.04

(7. 27) -42. 41

(7.09)

+327.3

(138. 9) +309.7

(136. 1) •+114.3

(162. 8) +430. 2

(234. 4)

+460.

3

(134. 8)

+447. 2

(134. 3) +449.

8

(134. 2)

+419. 2

(130. 9) +485. 5

(151. 3) +376. 5

(153. 4) +195.

4

(194. 7)

+461. 5

(250. 9) +586.

9

(142. 9)

+478.

1

(143. 9)

348.9

-855.

1

(323. 1) *-127.6

(413. 4) -1192.0

(520. 6)

-533.3

(224. 1) -1148.6

(420. 7) -349. 3

(297. 2)

+6579

(6549)

+1.5987

(7054) -10638

(12616)

+3138

(1661) +3103

(1787) *+1784

(3432)

334.8

286.6

363.8

+1. 594

(0. 130)

+1. 600

(0. 129)

+1. 604

(0. 129) +1.635

(0. 125)

335.4

+178. 2

(104. 7) +81.4

(18. 1) +119. 5

(19. 8)

333.5

333.4

-947. 2

(29. 9) -440. 4(214. 2) +3271(1428) 319.9

-197.

2

(59. 0) -223.0

(58.4) -129.4

(77. 0) -284.1

(90. 2)

+0. 7654

(0. 0700) -0. 7916

(0. 0699)

+0. 8325

(0. 0895) +0. 7417

(0. 1099)

344.6

-810.

7

(333. 8) *-84.

1

(421. 8) -1251.7

(553. 9)

-472.

1

(235. 0) -1063.2

(437. 5) -352. 7

(321. 8)

*+5848

(6611) +15160

(7240) *- 10822

(12792)

+2909

(1706) +2849

(1849) *+1862

(3470)

335.6

289.0

367.3

+1. 601

(0. 129) +1.628

(0. 127)

331.3

+269.

7

(232. 2) -943.

5

(318. 3) -351.9(224. 8) +2874

(1496) 320.8

major oxides instead of the major potential compounds as independent variables. The use of four

minor constituents in eq 6 resulted in a significantly lower S.D. value than was obtained in eq 5 although coef./s.d. ratios for two of the elements,

Co and Ti, were not very significant. Comparing

eqs 3 and 4, or 6 and 7, there is some evidence of a lower S.D. value where the turbidimeter fineness

values were used, although an additional variable was used in the two equations with APF.

The use of trace elements in eq 4 of table 7-15

for the NAE cements resulted in a significantly

lower S.D. value than in eq 1 where they were

not used. Equation 3 also had a lower S.D. value

than was obtained in eq 2, but the reduction

caused by the additional variables was significant

only at the five percent probability level. This

reduction was also found in comparing the S.D.

values of eqs 5 and 6. In comparing the equations

for the "odds" and "evens," eqs 3A, 3B, 6A, 6B,

there were instances where the SrO, Co, and Ti

had coef./s.d. ratios less than 1. Contributions of the independent variables to the 28-day compressive strength calculated from

the coefficients of eq 4 table 7-14 are presented

in table 7-16 together with the calculated ranges

of such contributions. Increases in C3S, C3A, and

fineness, and possibly C4AF and Zr, were asso- ciated with higher 28-day compressive strengths,

but increases in Loss, air content, and Cr, plus

possibly SrO and Co appear associated with lower

compressive strengths.

5.6. Compressive Strength of Water-Stored

Specimens at 1 Year

The frequency distributions of the 1-year

(water-stored) compressive strength values of the

different types of cement are presented in table

7-17. There was a considerable range of values

with each of the types as classified. The results of plotting the compressive strength

values versus some of the individual independent

variables are presented in figure 7-3. This figure

also presents the plots of the 1-year, moist-aii"-

stored specimens (STlM), the 1-year air-stored

specimens (STlA), and the 5-year water-stored

specimens (ST5Y). The 1-year, water-stored spec- imens had "quadrant-sum" absolute values greater

than 11 for the 4 major oxides, Na20, K2O,

C3A, C4AF, A/F, S/(A +F), fineness, and air content. It may be noted that the trends of the lines

drawn through the plotted points were different

in a number of instances than was observed at the

earlier test ages and presented in figure 7-2.

Selected equations relating the 1-year (waterstored), compressive strength values of AE +NAE

cements to various combinations of independent

variables are presented in table 7-18. Equation 1 indicates the relationship between strength and
n CO

CO rCO

o to

r— lo CM I—

I

Tf< 00 CO

-HOO

00 CO

in CD

r-- CO O OS

CO CO

00 (M

+ S2

CO C^l 00 CO ^ CO

! ^

a> o

>oco

CO 00

Woo O CO

I ^

irjco

I ^

oi 00 o »c CO o so

00 CO

I ^

iC CO

00 t-^ GO

a> TP

CI COCO

I

cooOS CO

__ ?p

CD r—

OJ CO

iO

'•31 00 w

^ S-ij* ^CC CO eO M CO GOO +^ CO.-I

iC o

CO to 22 ^ o to

CD CM +

CO o to

CO

CO ^

I ^

cot-- -^00 loco oor- lo >—

<

o *coi 05 Ofo co^o

00 CO oo

I ^

m o

1 ~-' 00 to

CO C-i m iO

1

to ^ ^ ^

I - I - I

I —

s

e

•-I o »H O ^ o

o o od

001^ oo

00,-H

GO vO

t-^ OS

CO

OS o

OS OS

CO CO

OS CO o o

1

iC 00 CO t-H

00 O O ' OS GO CO 00 cod

rHiO CNIO J?':? '-^O lOOS Oi-H 5^''"^

- + +^ +ci

s

CM CO '-N N _ , 0<M cot- too CO OiOi *^<z> §5 ^§ S«

00 00 I>t^ QOOi lOoo »oo" OS^H gg |g gg Kg 3|

f-t-^ coco CO 1—1 coo ^ CD iM CO '"'OS |g 5S 2S ss 5^

CO coco rH loS" O «3t^ O CO is SS s§ |g g?s + + + ++ +^

o

53s

Cm

00 o

CJ lO o c5

OScow

«M 00 +

CM+

o

CO CO 00

oo CM CM- -

I

o .

OS CM O CO

o . o . o .

I

II II

o .

CO CO

C-l CO OiS CO^ CO coo OcD "R; "SE t~co £!"

I

11 II

II

o .

CD CO o . o .

II II II II

oo \c>

II II o 3 a >

CO CO CO CO CO o . o . O . o . O . E-(TJ CQ c^ M CO CQ CO CO CO 03 03 CO

10
DEPENDENT

\MRIABLE

- INDEPENDENT VARIA 3LES

COMPRESSIVE

STRENGTH

AlzOj TOTAL A AIR P. WAGN. AIR AGE NOTE* S; O2 FezO, CaO M,0 SO, NojO KjO

ALKALI C5A CjS CjS C4AFF A + F FINE FINE 1:4 MORT

ft •

1 YEAH

(STIT)

(II

12)

13)

(4)

e

4 1/

L + 14

120

NL -24

102

L? + 18

102 rNL + 18to2

-10

66

NO

102 K

[\

L -17

10 10 2 2

L i L -18 1 -16

I

102

L -18

84

NO + 4

66

L? + 9

84

L? +12

102

L -15

I'j2 1/

L -18

102 KNL + 14120 kl

NL +24

102

NL

-15

1 VEAB * * *

IS T 1 M )

II)

(2)

2

1 / ^!

B

4 D\6 L

102

1 /

\/

8 84 2

102120 N84 |\102

1 ^K

84

7

3

j

84 tx

102102

1 ^r

102120 IV.

(3)

(4)

1-

1 +12

L -12 NO+ 2>- + 15-—I

L -12 L? -3L?

-14 NL

-17 L-24

L

-II NL + 9 L? + ' L? + 5 L? -7

NL '"-^NL +20 NL

-24

1 YEAR * * * *

(STIA)

(II

12)

(3)

(4)

102 ^:

L

-12

4 LNO

0

84

L? -6

8

4

LP + 8

7

5

L? + 7

S

4 KNL

+ 9

6

NO

-2

a

L? -5

84

L?-2

6

6

NO

+ 5

84 1/

L + 12

102 6

6 L.

NO

-5

6

6 LNO + 8

84

L?

-1

8

4

NL + 12

102

NL + 17

102

NL

-13

5 TEAKS * IST5Y)

II)

12)

3. ' 4 1

1 ^ i

102102

I--'

f

1/

1 -54

8

4

102

|VIV,

102 1\102 l\

102 !\8

4 \/

9

3

1/''''

•102

1/''''

102 K102

1K

1

'

!02

1

' 1

10 k 13) (4) NL 1 + 13

1^

L -17 L? + 12

L + 19 L?

-11 L? -12 NL-10

L -20

L -15 L

-19 L? +

1

L? + 8L? + 17 L

-18 NL

+ 15 NL+12

N L +24N L

Figure 7-3. Results of plotting compressive strength values at 1 year after water storage, moist air storage, air storage, and at 5 years after water storage of 1:2.75 {cement to graded Ottawa sand) mortars on the "Y" axis versus various independent

variables on the "X" axis. •Note (1) Ratio of number of plotted points in pairs of diametrically opposite quadrants. Note (2) General trend of lines drawn through plotted points. Note (3) Apparent nature of relationship. L=linear; NL=nonlinear; NO = no apparent relationship; and L? = nature of relationship not detennmable. Note (4) Quadrant sum in corner test. (See reference [8].) 'Stored in moist air for 24 hr, then in water for 1 year. •**Stored In moist air (95-100% RH) for 1 year. *'**Stored in moist air for 24 hr, then in water for 6 days, then in laboratory air 23 °C, 50 percent RH for 49 weeks, then in water for 2 weeks. ****Stored in moist air for 24 hr, then in water for 5 years.

Table 7-8. Calculated contribution of independent variables

to 3-day compressive strength in psi of 1:2.75 (cement to graded Ottawa sand) mortar cubes, water-stored, and the calculated ranges of such contributions

Independent

variable Range of variable

(percent)

Coefficients from eq 2

of table 7-6

Calculated

contribution

to ST03

Calculated range of contribution to ST03

Const. = -3048 CsS 20 to 65 +38.5 +770 to +2502 1732 CsA 1 to 15 +43.1 +43 to +646 603 SO3 1. 2 to 3.

0

+448 +538 to +1344 806 Loss 0. 3 to 3.

3

-247 -74 to -815 741 APF *2500 to 5500 +0. 789 +1972 to +4340 2368

Air, 1:4 mortar 1 to 21 -47.5 -48 to -998 950 K2O 0 to 1.1 +310 0 to +341 341 SrO 0 to 0.

4

-855 0 to -382 382 Mn 0 to 1.0 -533 0 to -533 533 Cr" 0 to 0.02 +6580 0 to +132 132 V" 0 to 0.

1

+3140 0 to +314 314

•cm2/g. **Doubtful significance. Coef/s.d. ratio less than 2.

the normally determined variables which were

found to be associated with the strength values.

The use of Insol, Rb, Sr, Co, and Mn in eq 4

resulted in a significant reduction in the S.D.

value (see table 7-75). Comparing eqs 2 and 3, where the turbidimeter fineness values were

used, the use of the trace elements also resulted

in a significant reduction in the S.D. value, but

in comparing eqs 6 and 7, the reduction was

Table 7-9. Frequency distribution of cements with respect

to 7-day compressive strength of 1:2.75 (cement to graded Ottawa sand) mortar cubes, water-stored

Compressive strength, psiXlO-'

1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 Type cement to to to to to to to to to to to to to Total

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 Number of cements

I 34

6

1

1733426 25 8 3 82

868

320

315

199

lA 1 II 3 22

2 2 1 IIA

III_ 1

1 4 3 4

2

4 3 1 IIIA IV &V 2

6

5

19

7

61

1

Total 51 29 13 6 6 4 3 1

significant only at the five percent probability

level (see table 7-75). Equations computed for

the "odds" and "evens" in the array of cements,

eqs 3A, 3B, 7A, and 7B, indicated that there were

instances where the FcgOa, Insol, Co, and Mn had

coef./s.d. ratios less than 1. The use of the turbidimeter fineness values resulted in lower S.D.

values than when the air-permeability fineness

values were used as may be noted in comparing

eqs 3 and 4, or 7 and 8. A similar series of equations are presented in

table 7-19 for the NAE cements and the combinations of independent variables associated with the

U
is o

(D

00 o

eo CO

I ^

CO o>

CO CO CO lO

I ^

CO o o

GO OO

00 <N OS oi

I ^

CD M

OS t--

CD (MCO

I

GO O

1—I lO CT> t-. Oi rf< OS »C

t-^ OS OS 00

I I

OS i-H

CO CM

to w

I ^

OS

GO CM

I

CO o

OOi-H

.-I o N o

00 o

o o OO

CD T-l CD O

-354.

9

(66.

6) co^ 00 00 OS OS

I—1 1-^ CM O

L10.7

(63.

6)

GO O CO CD

. o «^ CO 00^ CD

lO o

CD o OS 00

1 1 J ^ 1 ^

00 CD

OS —

+

00 o t— 1-1 CO t-(

C^l CD OO CD

OS O .-H CM OS r CO i-H OO 00 CO —t +

CO OS

CO CD 00 O

lO 00 OS OS CO .-" CO f-4

1-1 CO CO CD c4 lO »c

I I

+ +

''J^T-l Ol-I

00 I-l OS 1-H CO N + +

+ +

Oi CD

I-l fHCO +

f-H CO O O Oi CO

CO CO O CO o ^

II II II

H'O Eht3 H'O friV

e

t*5

s

K5

I Hm

Tj^O 00 F-H C^OS t~r-l 00 c4 oo-^ o-tjJ oiw

«3 F-^ 00 OS OS CD 00 iO Tf t-CO C^IiC COiO

, W I w I - -H^

OS

CO

I ^

^ CO OOW (N 00 I>-CD iC r-1 M id

t--. CO OM Oa O -^CD ID CO . o . OS too coos 1 M.<M CO iotp o-^ '^J^tM (MCO CO-* (TJ-^JH CO^ CO^ 1- I- I- 1- I- z +

O CO OSOO OS t>.C^ OS 00 t^i-^

i-JcD -^o "d"^ osio oci coco SS S3 3S +^ +- +-

00

iO --I 32 CO

t

t-- CO

I-l 00 o

o o +^

00 o od

I-l 00 Tti ^ CO

OS CO

I CO 00

I ^

M5 t~- CD CD O CO

O CO

CO CD

I - lO OS

CO CO 00 (M

S3 as

CO 00 i2 1-

CS I—I O i-< OO fO

o ^ +

CO l-O +

O CO

in ^

+

O OS

rH

c5co

CO CD +

0.-I

OO 00

iO+

OS CO CO »o CO w OS V

CO w

II II II

CO .-I OS ^

I

II II

r - 00

.-HO r*p_, '^'P, rHO +^

»n OS 00 CO

^ O I-l coco "2 CO O rH OS-^ irf-f g?;:^ as S2 5!£J +- +^ •- -

00 CO t>- CD

iC OS + +

W CO

12
Table 7-12. Calculated contribution of independent variables

to 7-day compressive strength in psi of 1:2.75 {cement to graded Ottawa sand) mortar cubes, water-stored, and the calculated ranges of such contributions

Coeffi- CalcuInde- Range of variable cients Calculated lated range pendent (percent) from eq 3 contribution of contri- variable of table to ST07 bution to 7-10 ST07

Const. = -2940 CsS 20 to fi5 -1-55.0 -f-110 to -f-3575 3465 C3A 1 to 15 -1-73.2 -h73 to -1-1098 1025 SO3 1.2 to 3.0 -f312 -1-374 to -1-936 562 Loss 0.3 to 3.3 -355 -106 to -1172 1066 APF - . *2500 to 5500 -1-0. 903 -1-2258 to -1-4960 2708

Air, 1:4 mortar 1 to 21 -63.9 -64 to -1342 1278 K2O 0 to 1.1 -t-426 0 to -1-469 469 MgO" 0 to 5 -19.8 0 to -99 99 SrO" .- 0 to 0.

4

-391 0 to -156 156

*cm2/g. ••Coefficient less than s.d. for AE-I-NAE cements, but greater for NAE

cements alone (see table 7-11).

T.VBLE 7-13. Frequency distribution of cements with respect

to 28-day compressive strength of 1:2.76 {cement to graded Ottawa sand) mortar cubes, water-stored

Compressive strength, p.s.i.XlO-'

Type 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 cement to to to to to to to to to to to to Total

2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0

Number of cements

I 3 10 28 14 17 9 1 82 lA 1 3 1 2 1 8

II 3 14 22 18 10 1 68 IIA 1 1 1 3

Ill "i' 1 4 3 5 2 4 20 IIIA 1 2 3 IV& v.. 1 '2

'e"

"5' 'i' 15

Total.. 1 7 7 33 67 35 33 14 6 2 4 199

1 year compressive strengths of water-stored

specimens. The results obtained with the NAE

cements alone were similar to those presented in

the previous table where computations for AE-fNAE cements were reported.

The contributions of the variables to the 1- year compressive strength of water-stored speci- mens were calculated from the coefficients of eq 4, table 7-18, and are presented in table 7-20

together with the calculated ranges of such contributions. Increases in fineness, and Zr appeared

associated with higher compressive strength

values, and increases in C3A, NaaO, Insol, air content, Rb, Co, and Mn appeared associated

with lower compressive strengths, though evidence

for a significant relationship is doubtful with

Insol, Co, and Mn.

5.7. Compressive Strength at 1 Year After

Moist-Air Storage

The frequency distributions of the strength

values after 1 year moist-air storage for the

different types of cement are presented in table

7-21. A broad range of values was obtained and

there was a great deal of overlapping of the values

obtained with the different types of cement.

00 10CO

I ^

CO 00 <c>

.-H O>Q0 Qi-^ CO

00 61 O -^f 2; ^ ^ CO »o <P

I ^ I

o in

<0OffO o r- (M 00 01

00 Ol

TP CO

I ^

CI o

01 0 --I o 00 to OS to 00 00 o O 1-1 lO lO

10 CO CO

Sr- CO

CO CO

CO

Ol CO

00 lO CO CO lO CO

»o CO CO

C-1 ^

I ^

CO Oi M O o o

01 O CO Tt< lO 00

CO t— 01 ^10

CO o

ifj CO

"2 GO

CO r-l 00

i-H O 00 C-l

I ^

^CO d c^I CO OS

I ^

00 <M

10 CO

00 o

O CO

•-I o I-H O

(M CO

c- i d

Oi OS

00

i-i

1-5 d rH O

OS o (M O 00

c-i 06 OlO (Mi-i "-I CI COCO «30S C-lr

1-H w <M ^ CO CO

CO CO CO

i-H CN

I ^ I

00 CO

06 ci

CO CO 1-4 rH O CO CO '

I

lO 00 CO t-^ CO "3

CO ^

I

coi>* 001

OS O I-H TJ* CO r 00(N 00 10

CO TP CO CO OS CO

Os^ 5-^ CO O 00

TJH OS 00 OS I-H OS O 00 Tji »o CO Tji CO CO <N

CO

OS I-H i-H O gI-H

OS CO 00 *c

I-""* (» I-H ^Os

(M -M

r-l ^

+

O I-I c4 06 +

CO r^'

00 CO

OS I-H +

ic 06 O 00 OS CO d I-H to t-^

-f

II II

ocD coco lOlo t--^ cocj I—Id r10 OJ OS (MO 10 coo O coos OS t— TP t-- ic oco 00s c3srI

II II II II II II II II II

fri'O E-i-a Eh'O Eh-o E-i'o E-ix) Wot MoT CQm cOot Mot CQot Mm

276-694 0-68—

2

13
14

o to

tj- CO

to ^

I

OS r- 00 00

< ^ CI f-( CM

-Hys (Mco ^5?:^

lO COCO

I ^

CO

252

O CO cc

iCJ 00 o>

00 to 10*0

CO CO

»0 CO

I

t-- CO

I ^

t-H CO

CI CI

.-I lO

l ^ CO

I ^

CI to ^ i-H 0> CI CI

r-l »o —I -TtH

CO I -

OS O i-H ^5^i ^H-^ S:=l

*C1 CI CI toco CIO

Cr >o C30 CI d o cj o o lo t-- oo co«o

00 lO

TP 00

lO CO

OS CO

r-^ CO ^ CO

CO » iH CO '-'OS 00 CO M to ^ <o

CI C-I

i-H O "-HO 1-t C) o

00 i-H oi 00 OS CO coo --1 O O OS I-H O OJ t^C^ CC-* CI CI CJCO

•-H O i-HO i-H O Ci O +- +-

»0

C5 0 oo

OrH coos r-ti-t OS O i-H t— 00 i-H ,H i-l 00 CO lO IQ OS !>. OS CO OOO lO --H OOCl O OS OS QO .-H O i-HOS i-H C^CO

looo

i-H-— oco Tj*ci 05C1 coos ^00 ,-hos CD CI tpc^ So ' C^lw '^rt '^'"^ i-H--^ Cl^ Cli-I I-H.-H "^i-H

coos loOS iCc-H OSCI CI Tit

>0 CI iH 00 Tj40 CO t"- iC OS O CO OS 1-^ OS

OS ^ rH CO 'T*^ c^^ + +

OS -f^i

o r-^ lo d M CO ooeo "-h ci CO!M CJ *0 d OOCO lOCO c +- +^ +^ +^

OS 1-H CO OS CO CO 00 00 oo Md -^i-H i^tO dS oco

ooos t^oo coo ot^ »co6 "^O »0 I-H OS rH O d OS d Od CJ +- +^ v- +- -r^ +

r-( 00 CO t-- + + +

^00 ^ d lOt-

^ 00

en M

QOt^ OCT> COOi 00 rH oa O

9ete ?3« a>o,

I +

II II II II

(M CO

- 3 CO «0

CO <M CO M

I ^ I -

II II II II

d CO

OS

I ^

E-i-d Hts Eh-o E-i'a H'O E-i'O Mm Mui CZlw CQot COt/i

Table 7-16. Calculated contribution of independent variables

to 28-day compressive strength in psi of 1:2.75 {cement

to graded Ottawa sand) mortar cubes, water-stored, and the calculated ranges of such contributions

Coefficients Calculated Independen' Range of from eq 4 Calculated range of variable variable of table contribution contribu*

(percent) 7-14 to ST28 ST28

Const. = +923

C3S 20 to 65 +46.0 +920 to +2990 2070 C3A 1 to 15 +70.5 +70 to +1058 988 C4AF** 1 to 16 +35.0 +35 to +560 525 Loss 0. 3 to 3.

3

-456 -137 to -1505 1368 APF 2500 to 5500 +0. 726 +1815 to +3993 2178

Air, 1:4 mortal 1 to 21 -90.2 -90 to -1894 1804 SrO** 0 to Q. 4 -952 0 to -381 381 Cr 0 to 0. 02 -24400 0 to -488 488 Co** 0 to 0. 01 -61800 0 to -618 618 Zr** 0 to 0.

5

+1720 0 to +860 860

*cm2/g. **Doubtful significance. Coef/s.d. ratio less than 2.

Table 7-17. Frequency distribution of cements with respect

to 1-year, water-stored, compressive strength of 1:2.75

{cement to graded Ottawa sand) mortar cubes

Compressive strength, psiXlO-'

Type Cement 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 Total

to to to to to to to to to to to

3.5 4.0 4.5 5.0 5.5 6.0 0.5 7.0 7.5 8.0 8.5 Number of cements

I.. 1 9 12 20 22 12 4 1 81 lA "i' 2 2 1 8

II i' 11 26 14 i' ~T i" 68 IIA 1 2 3

III "i 3 6 1 1 2 20 IIIA 1 2 3 IV&V 1 "i "4

3 l' 15

Total 1 2 3 11 17 35 55 37 25 9 3 198

The results of plotting the 1-year compressive

strength values versus the different individual

independent variables are presented in figure 7-3.

The variables having quadrant-sum absolute

values greater than 11 were, except for the Fe203,

C4AF, and the A/F ratio, the same as was obtained

when plotting the results of the 1-year waterstored specimens.

Equations relating the 1-year compressivestrength values of the moist-air stored specimens

to combinations of the various independent variables are presented in table 7-22 for the AE+

NAE cements, and in table 7-23 for the NAE

cements. Equation 1 of table 7-22 indicates the

relationship to commonly determined variables

all of which were found to be significant except

SO3, and eq 2 indicates the relationship with the

addition of the trace elements which were found

to be promising. The S.D. value obtained in eq 2 was significantly lower than in eq 1. This decrease was also found in comparing eqs 4 and 5 where

the major oxides were used as independent variables in the computations. It may be noted in eq

1 that C3A was the only one of the 4 major potential compounds which met the requirement that

the coef./s.d. ratio be greater than 1 when associated with the other independent variables used

in this equation. The SO3 did not meet this
CO '-t

r;-co to t~-

13S

to o

C2<M

CO lO 0> •*JH

I ^

Ira oCO

I

»0 CO

I ^

CI o O .-I O o CO o CO lO »C CO O f-^ CO CO so »o o

egco

oc>5 Si

M O

o ci Old iM CO 03 1-t cot- to*-' «Ot>.

I I ^

CO t-t

I ^

00

CO o

oi to

+

23 oo CO as CN{N

-I O i-H O oo --HO .-HO .-HO +^ +s

lO c> cooo oo

Oi .-H o ooo

COoiO .-H »oco

I ^

CO CO CD

CO O t^iO

OS CN IM M iC CD CO

CD do CO Tt< o

CO

CO CD O lO SSt cow r^T-« 2i'=^ o^ i-Hc^i £2c^

CO ic CO r^-^ CO »o

(^O

COCD CO CO <D (N 1-H r »2 ^ 03 o> O Oi OCO

OS O

C4 rH .-H CD CO TP Oi (M

(NCO OCO IMSD i-Ht-- ooep COCO moi 'Zi^ CM oi(M Oco oo"^

.-H O OS eD

OOO OI iO Tj4cO CO 03 CO OS

00 »o o to +

OS OS »0 CO

CO t-- f- CO + +

to CO O eD 7^ T"' 7

CO r-H »0 lO 00

CO to ,-H

*Os

coco

Or-". T

oo 1-H ^ OS (N

TJ* .-H 00 C3

CO Tp

00 —I

I ^

+

II li

coo r-oi t^r- .-HO TjiTp oo ooc oco coos ot-- r-eD .-im tor- oc coco OS CO CD to CO O* OS tf lO ^—' IQv—' tO'^ cO^^ SO''—' cO*^ tO'^ + + + + + + +

COCO

to C3 OS to lO^ +

OS OS t-v + + +.

fe5 to w

fi'q fH-a Eht3 fn'O

15
I ^

^ CO

I ^

lO CO

O <3> OS 4-^

2Sd o

lO O WCO CO

§s si

.-H CD

CO O

f-J CO O OS t-- ^

O CO

1

OS o> to

CO

Jo c5

CO

I

Id CO CO CO

I ^

OS OS OS CO s?s

M CO

CO 00 t-- O »-< 00 lO lO CD »6 to 05<M ^ W

(O CD CO vri

OS o 00 OS

OS i-H ^ o

OSoo

lO »0 00 T-( O 00 OS lO

tH <rj OS <N

OS O

oo o o +

oo

OS f, (M fM t-- OS o

lO CO

COcoo

I e

O OS CO M S ^ CO iC CO

o OS I-H O O

Tj« CO

r-- 00 lO

lO CO

I ^

oo CO ci o CD r-- co

00 o

OS

CD ^ C-) OS

lO 00

00 (M

CO CO --H

I ^

OS O

OS

CD 00 00 t- ^ S ^ CO O CO 1-H Ti<

ot3 »c

OS OS CO CD

(M 00 CD CO OS t—

OS OS 00 CD M

OS CDt^ M CD (N CO

I I

iO CO

00 OS

lOW "CW CO*-* cot-- t^N

MTh rHrJ? I^IO F-JrH C=3 CO c4 »0

O-"-! 00 rH CO >-H <M O CM OO*"" T

1"^ 1^ 1^ I

O OS

CD »0 CO CO + + + +

00 CO 0*0 OS oo00 00oo "3 + +

CO »o CO CO

00 + +

E-i'O ^"0 (ri"^ H'O Mw aiw Mwi H'O E-iTJ E-i'o w CQ TO MoT

i : <j PQ ; ; ; : <j m ;
Table 7-20. Calculated contribution of independent variables

to 1-year compressive strength in psi of 1:2.76 {cement to graded Ottawa sand) mortar cubes, water-stored, and the calculated ranges of such contributions

Independent

variable Range of vari- able (percent)

Coefficients from eq 4 of table 7-18

Calculated

contribution

to STIY

Calculated range of contribution to STIY

C3A 1 to 15 -83.8

Const. =+6714

-84 to -1257 1173 Na20 0 to 0.7 —918 0 to —643 643

Insol**-- --- 0 to 1.0 -647 0 to -647 647 APF •2500 to 5500 +0. 409 +1022 to +2250 1228

Air, 1:4 mortar 1 to 21 -97.3 -97 to -2043 1946 Rb 0 to 0. 01 -61700 0 to -617 617 Zr 0 to 0.

5

+2300 0 to +1150 1150 Co"- -- 0 to 0. 01 -53300 0 to -533 533 Mn". --- 0 to 1.0 -671 0 to -671 671

•CmVg.

••Doubtful significance. Coef/s.d. ratio less than 2.

T.\BLE 7-21. Frequency distribution of cements with respect

to 1-year, moist-air-stored, compressive strength of 1:2.75

{cement to graded Ottawa sand) mortar cubes

Compressive strength, psiXlO-' Type 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 Cement to to to to to to to to to to to to

3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 Total Number of cements

I 1 1 8 18 19 18 12 4 1 82 lA 1 1 2 2 2

8

8 II 16 20 10 9 4 1 68 HA 1 1 1 3 ni _ 1 1 "5" "i '3' "3' 20 niA "i' 2 3 IV& V . 2 3 3 "e' \ 15

Total.. 1 2 3 11 32 39 45 33 21 8 4 199

requirement with the variables in eq 1 but did

with those in eqs 2, 3, 4, 5, and 6. The coef./s.d.

ratio for Na20 was greater than 1 in eqs 1 and 2, (but not in eq 2B) and was less than 1 when Na20

was used with the variables in eqs 3 through 6. Equations for the "odds" and "evens," 2A, 2B,

5A, and 5B, indicated other instances where the

coef./s.d. ratios were less than 1. These variables were C3A, AI2O3, SO3, V, Co, and Cu. Comparing

eqs 2 and 3, or 5 and 6, it may be noted that the

S.D. values in equations calculated using the

Wagner fineness values were lower than when the

air-permeability fineness values were used, al- though differences in other variables used in the

two pairs of equations make the evidence for the

difference doubtful. Considering the group of equations as a whole, the evidence for a significant

effect due to SO3, V, Co, or Cu is rather small.

The coefficients of the different variables associated with the 1-year strengths of the NAE cements

alone, (table 7-23), were generallj^ consistent with

those presented in table 7-22 for the AE-|-NAE

cements. The contributions of the various independent

variables to the 1-year compressive strength of the moist-air-stored specimens were calculated

from eq 3 of table 7-22 and are presented in table 7-24 together with the ranges of these con-

<6

—I O —< COOS

00 00 :*3 00 CM r- o 0> CO Oi lO

00 S2 ss

cor* O CO

CD 10 COCO

I ^

a> to

CO CM

I ^

CO CM CO J>

CO CM SCOCO

OS+^

o 00

t£> CO

I

00*0 00 ^ CO CO iO •^10

*o o55 00 I— o cvitO OOOi

r-- lO 10 00 -H 00

»^ 1-H T)< CO COCO T^-^

01 CO t;^ 00

c3 <L CO CM CM CO CO 01 — ^ CO

I ^

CM CM ^ CO r-eo --"M

CO'*** cx)«o o«5 oo-* +^ +-

o CO CO

IC TP

CO CM

I ^

00 10 00 "O »2 «o

CM CO Oi O OS CO 00 w CM ^ .-I ^ i-« OS O lO

CO •—I o>c^ I- 7~-' I

? >o 00 OS Dco o3 oi C^ CO ^ OS CO O •-< OT I—• 01 ^ CO

I

10 M CM O ^ »0 CO +^ +-

CJ iO CM CO 0>C^ CO CM COCM ^ CM

CO Oi 00 i-lO

to CO

TP

»o ^O »o i-t 00

OS OS IO CM CO ^ go OS CO as t~^\

OS 00 CO OS 00 O OS o

CO 10 00

00

CO CM CM icco ot* osr- i-H-^

' •—"to CO 00 l>- OS ^ ' CM CO' xc' t-^ cm' 32 S2 SS S?3 2S «^ ^-^ ^. . +^. " ... . - . +^

lO CM CO

TJ« CM +-- +""

COCO ^CM ^CO

CO CM

I ^ I

I>» ^ CO ^

I - I -

TP O OS OS

1—I CO •—< IC OS "-H 00s ^ 1-1

- CO-"-" CM^ + +

+"-' +

CM "—I 100 r-C^ Tf* CD OS *o co»d ^co oiri ^"'C oJcd

(MIO OSCO 000 000s »D

O t— CO *0 QO O OS 00 10 !>

t-^id COM* *''^* OsCO kCrjI + +

g2

w?iO 000s oS _ iotj* o ic '^t^ ^ fo i2

»0 00 GO CM -_ lOOs coco

»OCO CM CM CO r-** Tj« CO + + + + +

II II II II II II

II II II II II II II II II II II II II II

E-i-d ^-6 E-ixj" E-iTS H-d H'^ E-i-d g-i-d f-i-d i*-6 ^ tfi CQm cCc/i Mtfi xn tn Mot Mot CQot* 02 ot CQot

17
CO CO ^ 1-1

CO

00 to coco

o oo

CO O

g2S 7

CC CO

O "3

o00 CO O CO

CO OS

ur> CO to

I ^

TP (M

I ^

OS

»H 00 W CO

1 ^

00 i-H so - CO lO c 01 O CO »

lO CO

CO M

I ^

CO ^

COCO

I ^

CO 00

(M 1—1 CO o>

oo

00

.-H O O 00

CO as X^ o

I

CO m" O OS

CO

g2 S§

00 (M

OS c^^

I

CO^h" O CO

ooco

I ^

CO

CO—

t

CO00 «D

OS fTJ

I ^

00 00

^o

OS lO 00

I ^ OS(NI ^

OS CO cor- "'OS o 00 §S §S

a,

CO

e

coco ^ o

coo O CO tC" a is -s. is

CD 00 OO

o*o o o

"3 ^ 00 - OS OS CO CD CD 00 ^

r-co Tf<o loco ^co csco lo^^' "^^o

90 oo IC O 00 c5 »o p eB CO CO

(N i-« CO >-< M

+~-' +^ +^

CD'^

CO 10 CO +

r— 'o— t— 1^ CO to cot— ^ 1- coco

I a

J

00 000 «o CO coco

C0C4 csco

CO 00 OS

00 CO 10 CO r- —I r- + +

CO CO

COco^ o t- t- CO

1 1 7 .1

+163.

5

(47.4)

+161.9

(46.0)

+158.

2

(56.

5)

+139.

1

(78.2) +153. 5

(46.0)

W CD 00 St ^ffi f^oo

Ttii-H D4C^ COC<l COCO iOi-f I- I w |w 1^

cor-t OS tt» CO

00 CO 000 +"'

II II

10 CO W CO

CO

11 II

00 o OS o O CD

CO <M O CO CO COCO jp^M ciSos ooc^ r-—( iooo toco rr CO T«co "^lo CO

I w I

I _ I ^ I -

II II II

II II II II II II

CQ CO to 03 w

18
tributions. Increases in fineness and P appear to be associated with higher compressive strength,

and increases in C3A, air content, Rb, and SrO

associated with lower compressive strength of the

moist-air-cured specimens. There is also a possibility that SO3 and MgO are associated with

higher compressive strength and Mn, Co, and Cu

are associated with lower compressive strength.

5.8. Compressive Strength at 1 Year of

Laboratory-Air- Stored Specimens

As mentioned in a previous subsection, these

specimens were stored in water for 6 days after the first 24 hr in the damp-closet. They were

then stored in laboratory air for 49 weeks, then

in water for 2 weeks, and tested in compression

in what was believed to be a saturated condition.

The frequency distributions of the compressive

strength values obtained with the different types

of cement are presented in table 7-25. The average

compressive strength values were close to those

obtained for the specimens stored in water for 28

days before testing. The relationship will be dealt

with in subsection 5.20.

Table 7-24. Calculated contribution of independent variables

to 1-year compressive strength in psi of 1:2.75 {cement to graded Ottawa sand) mortar cubes, moist-air-stored and

the calculated ranges of such contributions

Calculated Independ- Range of Coefficients Calculated range of ent variable variable from eq 3 of contribution contribu-

(percent) table 7-22 to STIM tion to STIM

Const. = +6306 C3A 1 to 15 -56.4 -56 to -846 790 SO3" 1.2 to 3.0 +188 +226 to +564 338 MgO»* 0 to 5.

0

-79.3 0 to -396 396 APF *2500 to 5500 +0. 646 +1365 to +3003 1638

Air, 1:4 mortar___ 1 to 21 -109 -109 to -2289 2180 Rb 0 to 0. 01 -106000 0 to -1060 1060 Mn** 0 to 1.

0

-607 0 to -607 607 P 0 to 0.

6

+904 0 to +452 452 Co** 0 to 0. 01 -36000 0 to -360 360 Cu*» 0 to 0. 05 -9600 0 to -480 480 SrO 0 to 0.

4

-1320 0 to -528 528

*cm2/g. **Doubtful significance. Coef./s.d. ratio less than 2.

Table 7-25. Frequency distribution of cements with respect

to 1-year, laboratory-air-stored, compressive strength of 1:2.76 {cement to graded Ottawa sand) mortar cubes

Compressive strength, psiXlO- 3

Type cement

3.0 to

3.5

3.5 to

4.0

4.0 to

4.5

4.5 to

5.0

5.0 to

5.5

5.5 to

6.0

6.0 to

6.5

6.5 to

7.0

7.0 to

7.5 Total

Number of cements

I 4 3 20

420

29

1 25

21

ii"

2

4 1 82

8

68 lA

II

1 1 16 "5"

IIA 1

1'

3

III IIIA ' W & V

"3"

1 "3" "7'

1 "s"

i

"i" 20

2

15 Total 1 8 12 48 62 37 18 9 3 198

The results of plotting the 1-year compressive

strength values of the air-stored specimens

\'ersus various individual independent variables are presented in figure 7-3. Only the Si02, C3S,

C2S, fineness, and an- content had "quadrantsum" absolute values greater than 11. A number of differences from those obtained with the water

or moist-air-stored specimens may be noted in the slopes or trends of some of the variables.

The relationship of the 1-year strength values

of air-stored specimens made of AE + NAE

cements to combinations of independent variables

are presented in equations in table 7-26. Equations 1, 2 and 5 indicate the relationships obtained with commonly determined variables, all of which were significant except Insol. The other

equations include trace elements which may have

an effect. However, Ba was the only one which

showed strong evidence of a significant effect. The reduction in variance resulting from the use

of the added variables was, in every instance,

highly significant (see table 7-75).

In equations calculated for the "odds" and

"evens", 3A, 3B, 6A, and 6B, there were instances

where the Si02, MgO, Insol, Cu, and Pb had

coef./s.d. ratios less than one. Equations 4 and 7 calculated using the air-permeabUity fineness

values had higher S.D. values than were obtained

in comparable eqs 3 and 6 where the turbidimeter

fineness values were used.

A comparable series of equations are presented

in table 7-27 to indicate the relationships calculated for the NAE cements alone. The coefficients

of the independent variables and the significance

of these coefficients are fairly similar to those

presented in the previous table for the AE+NAE

cements.

The contributions of the independent variables

to the compressive-strength values of the 1-year

air-stored specimens were calculated from the

coefficients of eq 4, table 7-26 and are presented

in table 7-28 together with the calculated ranges

of these contributions. Increases in C3S, fineness,

MgO, SO3 and possibly Pb appear associated with

higher compressive strength, and increases in air content and Ba with possibly Insol and Cu appear

associated with lower compressive strength.

5.9. Compressive Strength at 5 Years of

Water- Stored Specimens

The frequency distributions of the 5-year compressive-strength values of the cements of the

different types are presented in table 7-29. It was

previously noted in figure 7-1 that the average

compressive strength at 1, 5, and 10 years of the

type I cements was lower than the averages obtained with the other types. It is apparent, however, from table 7-29 that there was considerable

overlapping of the values in the dift'erent types.

The results of plotting the 5-year compressivestrength values versus individual independent

variables are presented in figure 7-3. Of the

various independent variables for which plots

19
00 to

CO i-H 00 CD

co^

I ^

1-1 00

CM «D lO i-< CO •—I CO 1-H

I - I ^

CM OS I—I CM O CO M< i-H

CO O

\o o

CM CO CO CO

CM

OSCO O-^ uOOl OlOs dOO CHO C-l'^ »COi TfHCM OOr-" iOtJh Tjloo c-it^ CMcd eoco q6c> •-Jic t^-^ C'icd cJoi '^ico

r>.co "O t-- com »oOi oo-^ c^ii^ r-co o»o coco oio cMr- —ICM ^CM POCM ^C^l iOTj< »OCM <n C-1 ^ C-i CMCM ^^ »OC^l |W [W I^J^ I- 1^ l"^J^ 1^ 1^

00^ 00^^ oou? coco osoo i-^Si co^ loC? ^^tr >oqq coco OOCO TjiuO (OtH "HC-l OCTi OOO- 01»0 C-ICO oc5 (DO r^o '-Hoi cm'i-h r^o «-Ici cooi osi-h" t^»o cio

lO ^ CD•-^ CO^ r-r-l lOi—I CO--! CD'— CD —' CO .—I IC r-H <X)i-H

CO tCO 00o o oo

^ o

CO O CD ^ o ^ o +^ 4-"^ +^

l>. CO

CD CO

OS CO Tj< I> 00

T-J 00 i-At-A CO CO

oo CO CM »0 00 CO 7^ I- +^

+ +

Oi CM CD oiOJ CO

^' CO

00 OS OJ CO CO O o CD Ot^ O 0)0 CM iC Oi iC CM'^ coo CO^

c^ico -^co 0»c r-'cp +^ +w

Tji iO CD CM CD IC OICM

CT> O CM

tT* OS »C CM

CO CM CM

OS O CM OS CM

TfH CO O 00

CO OI^fO ICCD OSt* t^CM + +

T) CM oo oi CD tUCO

C^Tji CM 1-H 00 00 OS od'O cm' CD 0»C> i-IcD ftdos o**^ CM^ CO — CO^ CO^ CM —' CO^ + + + + + +

^CO

OS CO CM iQ OS 00

CD Tr< co<5

I-, to O .-I OS CO

I ^

uo CO CO

CM O CO OS O CO

I

II II

OOCO

CO m

II II

E-i-o E-i'O E-i'O B'a E-i-a f-i-6 (ri-a MoT Mm tnt/5 Mm Mot Mot Mm Mot

<

Mot Mm
s

. CO CO oo C2f0

t-- —

t>. CD to O •-I 00 o> Oi

CO 00 i-H - +

o> «o CM

OlO OiCD WOi (M(D

i-HQO COCO i-iTti T+t-^ >0 O CO «5 T-l<0 ^ r-i CO'-H CO I-H >0 .-H CO i-H

I ^ I - I I w

1^7^ 1^ It^Ol 'O l"^ "OrH i-HCO COi—I OTt^ CO^ OlTf 00*0 CliC oico I-H Tji •^'^ coeo oi 1-4 cj-Tj* »or-^ co --^ oo ooco

rH o oo i-H 00 cor^ r^Tt< *oo o ^ oo r~- 1— lo o>o

<uDco -Leo ) -^co -^c^t Tt<cM rHco I coco

I

I ^ I I"" \^ * 1^

"*io CI 00 c^JO -^c-i r^co tQc^ 220 ^ ^ i-hcJ osco '=Of> <Oo5 oO'^t! y^'^ r^o ^^cc t^oo i-ho

oic^i 00 M f~- >—" »OrH "-^r-H 0> f-JrH CJi-H l>0 CDCO

^001 OiCl OCl .-Ccyj COfO COCN t-<M t^C^ i-HCO tPCO OiC^ |W 1^ I Y_ 1^ 1--^ |- I- |W |W

6q

^5;

<1S S3

O o

iH O

CD-*CD o t-. CO ,-HO I-HO 1-H O I-HO +^

I-H !>. CO O I-H Sg. O O CO 'ii

'f.ti ss? Si-H I-H OS 00 oo

CO 0> CO o-^

OS CD CD I-H !>• ^00 iO CD CD O CO Ol 00 00 COCl C-ICO OliO ^i-H

c^,-H Oco '^r c^oo SCO CDi-H lOi-H CD^ _u. CO M oo

CO I-H +^

ID CO »0

(M CD CO

CO <x>g> CO (M CO

COa> I-H CO CM +^

lO o>

CO ci

(3i

O CO to ^ *Ji o

CO r-^ 0'<*< c^-^ 00? c,,^ + + + +

+ + +

00 CI "^00 O I-H lO I—

CM r-- —

1-H ^ + + +

S»0 CI M CO

OS "-Ht^ lO 1-H ss. + + +

+

II II

S3 SE2

^•0 < ^6 E-i'O E-''d f-i'^
Table 7-28. Calculated contribution of independent variables

to 1-year compressive strength in psi of 1:2.76 {cement to graded Ottawa sand) mortar cubes, air-stored, and the calculated ranges of such contributions

Inaependent

variable Eange of variable

(percent)

cisnts

from. CQ 4

of t&blG

7 Oft

uaicuiateci contribution

10 0 1 lA

Kj aictiiaieQ range of contribution to STIA

CsS 20 to 65 +30.4 +608 to +1976 1368 SO3-- ^ 1.2 to 3.0 +427 +512 to +1281 769 MgO 0 to 5.0 +86.7 0 to +434 434 APF *2500 to 5500 +0. 454 +1135 to +2497 1362

Air, 1:4 11 to 21 -67.2 -67 to -1411 1344 mortar. Insol." 0 to 1.0 -521 0 to -521 521 Cu»* 0 to 0.05 -7322 0 to -366 366 Ba 0 to 0.2 -3485 0 to -697 697 Pb** -- 0 to 0. 05 +9390 0 to +470 470

*cm2/g **Doubtful significance. Coef./s.d. ratio less than 2.

Table 7-29. Frequency distribution of cements with respect

to 5-year, water-stored, compressive strength of 1:2.75

{cement to graded Ottawa sand) mortar cubes

Compressive strength, psi X 10-' Type 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 Total cement to to to to to to to to to to to to 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 Number of cements

I 1 5 14 12 18 20 7 3 80 lA '2 2 1 2 1 8

II 1 1 "4 6 17 22 12 i' i' 65 IIA 1 1 III 1 "3 "8 "5 1"

i 19 IIIA 1 1 2 IV&V " i "i 4 ""6 3' 15

Total.- 2 3 7 17 17 28 41 42 26 5 2 190

were made, only Na20, C3S, and C2S had quadrant

sum absolute values less than 1 1

.

Equations relating the 5-year compressivestrength values of the AE-f-NAE cements to combinations of independent variables are pre- sented in table 7-30. In eqs 1 and 4 are presented

the relationships with commonly determined variables, and in eqs 2 and 5 the trace elements

having coef./s.d. ratios greater than 1 were in- cluded. Of all the trace elements included here,

only Rb showed strong consistent evidence of having a significant effect. The S.D. value of eq

2 with the added variables was significantly

lower than the S.D. value of eq 1. (Equations 4

and 5 are strictly not comparable but there was

approximately the same reduction in the S.D.

value as in eqs 1 and 2.) In the equations calculated for the "odds" and "evens," 2A, 2B, 5A, and

5B, there were instances where MgO, Insol, Zn,

Zr, Ni, and SrO had coef./s.d. ratios less than 1. Although the quadrant sum of SO3 was greater

than 11 in figure 7-3 it was not significant in the

multiple regression equations. C2S, on the other

hand, had a quadrant sum less than 11 in figure

7-3 but was significant in the equations in table

7-30. Equations 2 and 5 calculated using the

turbidimeter fineness values had slightly lower

COO>

I ^

O OO <N CO ai<o 00

CO 00 OS O W (NO 1-1 4,<M +^ 7^

CO o>

OS CO »c

OS lO I— o 'O CO

CO rH T-H >-( +- +-

IQ CO +^ +-

eg 00 o 00 +-

0 CO

CO OS +^

to 0 0CO m

455) to 1 OS »o . G0(0 < CO

' CO 00

+2995

(1470) 00 CM

OS CO +£i

i

> (N

; +^ +"

OsS^ to 00

00

CO >o 0 o"

(M <X) 1 0 CO S

i-H W OS r- OS *-l

f-H »0 CM CD CO

CO CO

gs

OS 10 CO IN • 25 CM .

1 (O CO .-H 10 M «i

1

to 00

t~- OS U (N CO CM

00 CO <oco +^

CO OS CO o o

CO o +^ +" +' S5S

00 <0 OS

OS CO O "-1 to CO 10 PO

TP 1-t O OS 00 o

O CI QQ CO CO

OS OS

OS

OS O CD <o

»o to

OS o 10 CO CO

I -

CO O CO

C*3 CO OS CO

iM CO

00 1-t CD CO

I ^

OS i-H O --t CO i2 O CO CO

Tj« »0 OS CO 10 CD

CO CO

1-1 CO

I ^

iC OS CO

J 1-H CO OS OS 10 t"

'"^

0> (M OS M t» o

M 1-5 CO ^ Sd Sci 3- -|

I I I

'

coo

CO ui

1-H ^ 00 --H 52 00 ^00 »-i 00 CO o COi-l CO r-t lOcO

.-i o ^ p o +" +-

3?5 +s

.-H CO t-f

CO CO r-fO ^O r^O rHC

01 1000

*n o $0

CO o

OS CO

10 o

SS*"- J? t- »0 Oc^ coco CO CO CO«C t;Tt< (NeO coS S-S* 5S HCM 2" ^l** O oR cog ^ — coco

CO OS I-H

+163. (55.

+142. (54.

+94. (84.

+184. (74.+178. (56.

+247.2

(34.7) +220.

6

(33.

6)

+

+202.4

(43.7)

+283.8

(35.7)

iM (N .-no r- oico

(Nl-, !NOS COiO C^t'- OS

\ii (A or>^ 'O vo CO 1-^ u£

COr-t CO CM '^C<i COw-i

I - I I ^ I - I

lO xo 05 "O t^co ^O COeO M ^•o OOCO t^oo O .-I coco t^CO OOS *50S OSf^ i-iw cq"—' "T^"^ 1-1^

+ + + + +

01 CO

CD (N o 10

l> CO

OS CO S CO

II II II II II +

00 7""

epos

I 2

II II

II

to .

10 OS

1-H

I

II II

«3 . fHT3 E-f"^ H*^' E-i-d CQcr (TIot CQai cQw CQw CQw

22
-^6

S 5

r- oo

to I-H CO LO

CO cr> (M 00

OJ to

CO (M

CO

iC CO

00

00 CD OQ 00 o

CO

CO o (M .-H

(N CD

CM

r- 1—

I

CO 00 CO 00

CO

I ^

to o CO CO "—J C3 CD (M

CO CO

OO »C (N t- O CO (M

rH i-H c!) ^

oi r- OS CO

*H OS o

CD CO .-H t'. CO CO Ml— CM T-H

CO CO -^00 O »0 O 00

T-lOs ^ c3 CO --H <M .-H

wo (MO

CO M »0 O

lO (M CO o OS to

00 OS

OS OS coco o to

CO o »o »o O U5

<M 00 (MM* 23.

'J

CO (tJ

CO OS O

t— 00

OS O CO tn

I ^

coco ^ oi h- CO

CO CO

OS CO

I ^

c^ta co'^ c CO >o T

I I ^ r

SCOCO

I ^

Or-- o CO

OS CO CO M lO CO Olo wos lo o-^ (Ntj^ oi-^ oseo t^r^ c5-^ t-M »OM C0<N i-lTt* W <DC<I f T"" T"" T"" T""

-<i<r^ (N OS OS CO

rHO »H O oo --HO +^ +^ +^

Tt* lO OS 00 ^

CO i-H M '-H OS

f-J o o op.

oo

CD O oO <M

oir-- i>.^ COO (N OS OS o COiO C0*0 OOO cD»0 CO

OS CNJ i-HM coco T-*CO O (M

CO OS OS »o (N .-1 oor-

»o OOl

00 00

CO O I-H lO St-- oo ic +^

* +^ +^

O r-l LO 00 CO OS CO CO o o »o + +

t> CO CD O + +

t-^ CD

00 r^,

I ^

« 00 CO »-t

I ^

OS "5 t00 --H

CO eo

i-H CO

1-1 CO

LO CO OS OS

00o »o +

II II +

II II

CQ to

O S 00 o o iC "O +

II II

CO CM

CO OS

I ^

C<1 00 O O 00 CO

I c

II II II II II II

OS »0 to

i-i CD OS

II II II

CO to

S.D. values than corresponding eqs 3 and 6 using

the air-permeabiUty fineness values.

Equations calculated for the relationships of various independent variables to the 5-year compressive-strength values of the NAE cements are presented in table 7-31. The coefficients differ to a limited extent from those presented in the pre- vious table for the AE+NAE cements. In table

7-31, the addition of the trace elements in eq 2 resulted in an S.D. value lower only at the five percent probability level than the S.D. value in

eq 1. Equations for the "odds" and "evens" indicated instances where C2S, Fe203, Zr and Ni had

coef./s.d. ratios less than 1. As in the previous

equation, MgO and SrO were not included in eqs

4 through 6 because the coef./s.d. ratio was less than 1 for these variables.

The contributions and ranges of contributions

of the independent variables to the 5-year compressive strength were calculated from eq 3 of table 7-30 and are presented in table 7-32 together

with the ranges of these contributions. Increases

in C2S, fineness, and Zr with possibly Zn and Ni

appeared associated with higher strengths, and

increases in C3A, Na20, air content, Insol, and Rb

with possibly MgO appeared associated with lower

strengths at 5 years.

5.10. Compressive Strength at 10 Years of

Water-Stored Specimens

The frequency distributions of the 10-year

compressive-strength values obtained with ce- ments of the different types are presented in table 7-33. There was a broad distribution as well as a great deal of overlapping of the compressive-strength values of the different types of

cement.

Table 7-32. Calculated contribution of independent variables

to 5-year compressive strength in psi of 1:2.75 {cement to graded Ottawa sand) mortar cubes, water-stored, and calculated ranges of such contributions.

Calculated Independent Range of vari- Coefficients Calculated con- range of variable able (percent) from eq 3 of tribution to contributable 7-30 ST5W tion to ST5W

Const. = +5978

C2S 5 to 50 +19.1 +96 to +955 859 C3A 1 to 15 -87.5 -88 to -1302 1214 Na20 0 to 0.

7

-1230 Oto -861 861 APF •2500 to 5500 +0. 604 +1260 to +2772 1512

Air, 1:4 mortar 1 to 21 -113 -113 to -2373 2260 MgO" 0 to 5.

0

-64.5 Oto -322 322

Insol - - 0 to 1. 0 -702 Oto -702 702 Rb 0 to 0. 01 -68900 Oto -689 689 Zn" 0 to 0. 2 +1900 Oto +380 380 Zr 0 to 0. 5 +2190 0 to +1080 1080 Ni" 0 to 0. 02 +17700 Oto +354 354

*cm2/g. •'Doubtful significance. Coef./s.d. ratio less than 2.

Equations indicating the relationship of dif- ferent combinations of independent variables to the 10-year compressive strength values of AE+NAE cements are presented in table 7-34.

Equations 1, 2, 3, 6, and 7 were computed with

23
as in eqs 8 and 9, and was not significant in eqs 3 i and 5 where the compounds were used. ;j A similar series of equations are presented in Is table 7-35 for the NAE cements alone. The same li variables were significant but there were slight ; difl^erences in the coefficients for these variables | than when the AE cements were included as in { table 7-34. It may be noted that the "air, 1:4

j mortar" was highly significant in both tables | 7-34 and 7-35. Also, in both of these tables the i S.D. values of equations calculated using the Wagner j j finenesses were lower than when the APF values i were used. \l The contributions of the various independent ji variables to the 10-year compressive-strength ( values were calculated from eq 5 of table 7-34 and ij are presented in table 7-36 together with the i ranges of these contributions. Increases in CoS, ji fineness, and Zr, with possibly Zn and Cr, appear i associated with higher compressive strength values ; i at 10 years, and increases in C3A, C4AF, Na20, 1 and air content, plus possibly Insol and SrO, j appear associated with lower strength vakies.

5.11. Gain in Compressive Strength Between j] 7 and 28 Days ji The frequency distributions of the 7- to 28-day 1! compressive-strength gain of the different types 'i of cement are presented in table 7-37. There was a i| range of values within each of the types and a i' considerable overlapping of the values found for : the different types of cement. h The results of plotting the 28-day minus 7-day

compressive-strength difference versus individual i variables are presented in figure 7-4. Of the :

DEPENDENT

VARIABLE INDEPENDENT VARIABLES

COMPRESSIVE

STRENGTH

DIFFERENCE NOTE* Si 0: AljO, FejOj M,0 SO, NojO KjO TOTAL

ALKALI C3A C,S C^S C,AF A

F SA +F

AIR P. FINE WAGN.

FINE

AIR

1:4 MORI

28 DAY MINUS

7 DAY

(1)

(2)

10z 1/

4 k

102 1/

£

6

6^6

102 |\102102102 k102 K_e4 |\102 k

102 k

84 k

102102 k

6_6

102

(ST28-ST07) k (3)

(4) L + 15 NL

-II

L + 15 NO -2

NO

0

L -20 L?-8L?

-17 NL -20

NO

-14

L

-10

L +16

L + 16 L

-12

L? + 13 NL

-13 NO

-3

NL

-17

1 YEAR WATER- STORED MINUS

7 DAY

(II

(2)

120 1/120 l\

1206

6

8

4

120 |\102

120 K

120102 l\

102 |\120 1/102 k120 k102 k

8

4 k

84

1

102

(STIY-ST07) (3)

(4) L + 24

1. -24 NL + 24

L? -7L? -7L -24L? -14L -24L? -24L -20L -16 L + 24 NL + 16 L -24

L +20

NL -7NO + 2

L? -13

1 YEAR AIR STORED**

MINUS

7 DAY

ID

12)

120

102 l\84102102 K1027

5

6

6

8

4

102 |\

120 k120 kB

4 k

102 k102

B

4 k

666

6

(STIA-ST07) (3) L +24

L

-18

L + 15 L

-17 NL

+15 NL

-15 L? +3 L? -7

L? -4L -19 NL -24L + 24L

+12

L -19L? +14 NL

-10 NO

-1 NO

-5

Figure 7-4. Result of plotting difference of compressive strength at different ages of 1:2.76 {cement to graded Ottawa sand)

mortars on the "Y" axis versus various independent variables on the "X" axis.

| *Note (1) Ratio of number of plotted points in pairs of diametrically opposite quadrants. Note (2) General trend of lines drawn through plotted points. Note (3) Apparent nature of relationship. L = linear: NL-nonlinear; NO-no apparent relationship; and L?-nature of relationship not determinable. Note (4) Quadrant sum in corner test. (See reference [8].) ; **Stored in moist air for 24 hrs., then water for 6 days, then in laboratoi-y air at 23° C, 60 percent RH for 49 weeks, then water for 2 weeks.

Table 7-33. Frequency distribution of cements with respect

to 10 year compressive strength of 1:2.75 {cement to graded Ottawa sand) mortar cubes, water-stored.

Compressive strength changes, psiXlO-'

Type 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 Cement to to to to to to to to to to to to Total

3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5

Number of cements

I 2 8 9 9 17 21 9 3 78 lA 'i' 3 2 1 1 8

II 1 2 2

'5' 18 7 14 4 3 56 IIAkl'I 1 1 2 ni 1' '5' 4

'3" 1' 16 niA 1 1 2 rv&v 1'

1 2 1 1 1 7

Total.. 1 5 11 14 11 26 47 23 20 6 4 1 169

commonly determined variables, and eqs 4, 5,

8, and 9 with the addition of the trace elements

found to have coef./s.d. ratios greater than 1. Equation 1 had a significantly lower S.D. value

than was obtained for the 155 strength values of the cements themselves. Comparisons of eqs 1 and 3, 3 and 4, 2 and 5, 6 and 7, or 7 and 8 indi- cate that a highly significant reduction in the

S.D. value was obtained in every instance as a

result of the added independent variables. However, of the trace elements added, only Zr consistently showed a strong significant relationship.

Equations calculated for the "odds" and

"evens" in the array of cements indicated that

C4AF, Insol, SrO, Zr, Co, and Cr had coef./s.d.

ratios less than 1 in one or the other of the groups.

The coef./s.d. ratio for Cr was less than 1 when

the oxide values were used in the computations
oolO 00 CO o

>-t 00 iO CN

(M 00 3S

lO CO »0 CO co«o

O CO

IC CO

to eo a?3

sor^co

CO CO CO CO

sr1 CO 00

oo O lO ::?3

00 00

I

C0»0 COC3

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^tc^" t-c^' »-<o6 "^00 t^co

O--! OiW ^ ,-H ^ 1^ 7^ 1^ 1^ 7^

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I I

I

•-« TP r-- >o (O

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,-H o o o ^ o oo

2

+

a.s

"Si e

CO

OS N OO

to rH o ci

O (3) CO C5 »^:» o ,_v^ <00> 05^0 OICD

<Oc^, tow SjCO »o

joco oooo cot- Olt

»0COiii-Tt-^ ix"* ^050O 00ooCn

£22£ t~~m J?^ cH^ r-co r-co (-^»c

CO o

CO Oi ^ *o oo(M COCO coca coo

PCO w lO _ , CO CO CO O CO

I - I - I "

cor- CO coo o> o »o ooo S§s 2S §^ r"-^ »HN_' + + + + + +

c^S" ^ 00 '-H^ eo»o

»o CD t; CO im" CO ci Tt< i:: ^v^ Tt<w co^ cow fo"^ eo*^ + + + + + +

CO o ^ r>> Or— ^ to ooco r^c-i coca "^ci

CO

cm' r-*

s

OOCO

coo

t- o

O 00 +^ +

CO

00 o

00 lO 1 S w Si

I

I

<M 00 OS Oi ooi-H N*** ^CO CO (N ON.

t^co

CD CO CO ^

00 CM

00 CO CO CD

CO

00 t- oo

03 00

Tj< O

00 ^

COC2 o so + +

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< X . Ehx) E^'O E-iTj E-'x)

25
CO o CO go

CO o

O 00CO

-tp CO CO

CO 'O

3i is

CO

CI "5

CO CO

(M CO

r>- CO

to

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1

CI o

I ^

(N CO

"5 1-1

"53

'13 .8

CO

S

Si

CDs

O OS

r-i

o> O iC 7"" 7

0 OS CO t-- 01 CO +^

3§

CO o

0> CO

I ^ 7" CO

CO

00 CO

(M CO

OJ

OS OS

I

CO OC^ coco OOCO '^'^ C-1iO C^OO O-"-" COtO C^IO COr-H q!90 !£fe gg^ O CI iO CO

!

OOCO

r-' CO

I

CO .-H d

I

O OS CDOO o o

Tjt o CO o OS CI

CD C^i CD CO

CO l>^ O CO o o

4-^

"Si s

a.S

I

CO

I w«

CO i-( O O

CO CD Ol OO O O O O

TP i-H CJ O

o o OO OO

1-^ l-l CO

eo W3 OOCO

1 ^

C3CO N CO

i-H

I

OS CO »o

O CO

05 CO

I ^

>0 .-H CO Ol

OS CO

I ^

OSOS CO

OS CO

I

StOOCO

I ^ CO OS

I ^ I -

CO 00 CO OS

la CO

I

OCD OOOS OS ^ COCO '-H '«*4 lOi-H COOS 00 C^" Cdr-I Oit-^ OOiC

oico coco Tt< CO cocD coo ^-^

Tt*S" 00^ 00 00 <Mt^

coui coco" »o»d r^N tr*-* ocJ 53. is gs. + + + + + +

»0 CD

CO CJ

I

CD

I ^

CO CO

»0 CI

1 ^

00 CO,

lO o

00 coosOS

OS o

CO "5 cdci

iC CI O CJ, CD eo

CI

I ^

CI

T

+

II II

00 w

+

II II

03 m

O M +

II II

.

CO w

CO UO

go CO Oeo ^

I

CO O

II II II

CO ^ °o " I -

II II II

(eve

t« X . X . X . . X . X! . X . Eh 13 Eht) H'O

CO m CO m CO CO CO m to M CO to CO to

26
Table 7-36. Calculated contribulion of independent variables

to 10-year compressive strength in psi of 1:2.75 {cement to graded Ottawa sand) mortar cubes, water-stored, and the calculated ranges of such contributions

Calculated Independent Range of Coefficients Calculated range of

variable variable from eq (5) contribution contribu-

(percent) of table 7-34 to STXY tion to STXY

Const. = +7043 CjA 1 to 15 —132 —132 to —1980 1848 C2S — 5 to 50 +20.

0

+100 to +1000 900 CiAF— 1 to 16 -52.4 -52 to -838 786

0 to 1.0 —719 0 to —719 719 Na20 0 to 0. 7 -1650 0 to -1155 1155 APF •2500 to 5500 +0. 309 +773 to +1700 927

Air, 1:4 mortar 1 to 21 -113 -113 to -2373 2260 SrO" 0 to 0.

4

-847 0 to -339 339 Zr 0 to 0.

5

+3380 0 to -1690 1690 Zn" 0 to 0.

2

+3650 0 to +730 730 Cr" 0 to 0.02 +15100 0 to +302 302

•cm2/g. ••Doubtful significance. Coef./s.d. ratio less than 2.

Tabue 7-37. Frequency distribution of cements with respect

to compressive strength gain from 7 to 28 days of 1:2.75

{cement to graded Ottawa sand) mortar cubes, water-stored

Compressive strength gain, psiXlO-'

0 0.5 1.0 1.5 2.0 2.5 3 .0 3.5 Type cement to to to to to to t 0 to Total

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Number of cements

I 4 24 36 14 4 _ 82 lA 1 5 1 1 8

II 1 6 25 13" ; 1 68 IIA 1 2 3 in 2 3 "¥ 7 i' 20 inA 1 1 1 3 IV & V 1 9 3 i . 1 15

Total 3 11 44 80 41 18 - 2 199

|| variables for which plots were made, all but CaO,

MgO, NajO, C3S, and WAGN had quadrant-sum

absolute values greater than 1 1

.

j Equations relating the 7- to 28-day compressive-

: strength gain to combinations of independent

variables are presented in table 7-38 for the

AE+NAE cements, and in table 7-39 for the

NAE cements. The use of the variables in eq 1 or

the use of additional variables as in eqs 2 and 3 each resulted in a significantly lower S.D. value.

I Similar reductions may also be noted in comparing

I eqs 5 and 6, or 6 and 7 (see table 7-75). Compariji sons may be made of the variables in table 7-39

jj with the variables associated mth the compressive

1 strength values at 7 and 28 days in tables 7-10

1 and 7-14 respectively. Some of the independent

I variables which were significant at 7 and/or 28

h days (tables 7-10 and 7-14) were not significant

II in table 7-38 where the difference in strength was

ij the dependent variable. Also, some variables

which were significant in table 7-38 were not significant in tables 7-10 or 7-14.

1 Equations calculated for the "odds" and

"evens" in the array of cements indicated, that

for the smaller groups, there were instances where

C4AF, Fe^O,,, K2O, APF, Zr, Cr, Co, V, and Ni

had coef./s.d. ratios less than one. The coefficients for the independent variables

in equations calculated for the NAE cements

alone and presented in table 7-39 were, in general,

concordant with those of the previous table, 7-38,

where the AE cements were included.

The contributions of the variables to the

strength-gain values between 7 and 28 days were

calculated from the coefficients of eq 4, table 7-38,

and are presented in table 7-40 together with the

calculated ranges of these contributions. Of the

different variables, increases in C4AF and Zr were

the only ones associated 'with a greater compressive-strength gain. The values in the last column

appear to indicate that no one variable is highly

dominant in its effect. Cr was associated \vith

lower strength gain and Rb, Co, V, and Ni were

of doubtful significance.

5.12. Compressive Strength-Gain Ratio, (28

day—7 day)/7 day, or SGR(l)

Frequency distributions of the compressivestrength-gain ratios, (SGR(l)), are presented in

table 7-41 for the different types of cement. Although there was considerable overlapping of the

values obtained mth the cements in the different

t3rpes, most of the Type III cements had low

ratios as may be expected with the higher earlystrength cements.

Equations relating SGIl(l) for AE+NAE ce- ments to combinations of independent variables

are presented in table 7-42, and for the NAE

cements alone, in table 7-43. Equations 1, 2, 5, and 6 were calculated using commonly determined

independent variables, and the other equations with

additional variables, the trace elements found to. have a coef./s.d. ratio greater than one. The addition of these elements resulted, in every instance,

in a highly significant reduction of the S.D. values.

(See table 7-75.) Of the trace elements used,

however, only Zr and Cr showed strong evidence

of a significant effect, and Ti was borderhne.

Equations calculated for the "odds" and

"evens" indicated that NaaO, Zr, Ti, Pb, and V

had coef./s.d. ratios less than one in one or the

other of the smaller groups of cement.

The equations for the NAE cements in table

7-43 are fairly concordant with those in the

previous table where the AE cements were in- cluded. In the equation for the "odds" and

"evens," NaaO and Zr had coef./s.d. ratios greater

than 1, and that for Cr was less than 1. A comparison of tables 7-42, 7-38, 7-10, and

7-14 shows that, of all the trace elements in- vestigated, Cr was the only one which showed

strong consistent evidence of a significant relationship to the strength alone, and then only at 28

days. However, with both the strength gain and

strength-gain ratio, both Cr and Zr showed good

evidence of a significant effect. None of the other

trace elements showed strong e\'idence of in27
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312.2 364.7

1 i

: 1

(9B46)

-35558

(13188) •+3031

(15577)

>

; f

(1Mb)

-4694 (2658)

•-1049

(2269)

-2596

(1645)

-26066

(20158)

—59060

* III 1 i ill Ii-' +•

Pi

i 1'

: S

: 1

~If

(2338B;

-39578 (24867)

-29440 ii

; 1

-31885

(22039)

-35016 1

o -20021

(7012)

•-6558 ll -18383

(7357)

•+1773 -34169 (10717)

+1414

(669)

+4827

(1699) +865

(786)

+1385

(669)

i fill

Air

1:

4

mortar

\ 3i ?3S 3? i

1 fs f& fs fs 1 t « • 1

-33.

42

(18.71)

-26.40

(17.53)

-28.88

(24.70)

•-24.

20

(26.45)

o

1 ooSo t-c? oS cno 1 fi IS fi fi is i

; «s ooSo coS oo^f

1 Si ii ii ii

-0.2109 (0.

0696)

-0.

1447 1 il il ii il il il il il il

= oo oo oo do oo oo oo oo oo

W

-253.0

(149.3) —224.

7

(163.

1)

•-98.2

(234.0)

-354.0 (257.3)

-304.6

(161.5)

; CoS? t-30 OOSO t-S

i fi fi fi ig

o

!z;

-299.4 (186.

6)

-423.

2

(177.0) -534.

1

(217.

5)

-574.

7

(330.

0)

-440.7

(178.2)

: ojS ooS- rq^r

i fi fg fi fi

o

•+10.48 (29.

02)

—90.

58

(31.17) -75.

61

(29.29) -96.

20

(35.82)

-67.38

(49.85)

1 +205.

1

(46.2)

+109.6

(44.4)

+141.0

(42.3)

+120.3

(59.3)

+151.5

(63.8)

sg 5§ ^§ s§g ; js is is %t \ s§ g3§ s5 si §i : f i ^ 1

O i :

; 1 ;

io

SG(1)

=+2157

s.d.

=

(264)

SG(1)

=+2946

s.d.

=

(285)

SG(1)

=+3246

s.d.

=

(287)

SG(1)

(odd)

=

+3167

S.d.

=

(408)

SG(1)

(even)

=

+3294

s.d.

=

(425)

SG(1)

=+3907

s.d.

=

(353)

SG(1)

=+1535

s.d.

=

(1914)

SG(1)

=+9168 1 il i| 1!

1 II II ji^ii XII

d S

^ go's m'S CD'S £££££££££££

«' < eq'
Table 7-40. Calculated contribution of independent variables

to compressive strength gain in psi from 7 to 28 days,

SG(1), of 1:2.75 {cement to graded Ottawa sand) mortar

cubes, water-stored, and the calculated ranges of such

contributions

oaiculatcu

In- xvtllif^tJ Ul O06iriciGn.ts 1 ^ 1 oaiciiiartGci range of

V dJ IttUlc 11 uiii y't

}

contribution contribu01 Idulti / 00 tion to oU(l)

C3S on in P,^ 03 •7CO 768

1 to 16 +48. 58 4_dQ f-n -1-777 NazO 0 to 0.7 -m. 5 Oto -329 329 K2O 0 to 1.1 -332.2 Oto -365 365 APF *2500 to 5500 -0.2164 -541 to -1190 649 SO3 - 1.2 to 3.0 -340.

3

-408 to -1021 613

Air, 1:4 mortar.

.

1 to 21 -27. 10 -27 to -569 542 Zr 0 to 0.5 +1338 Oto +669 669 Or 0 to 0.02 -23043 Oto -461 461 Rb" 0 to 0.01 -25000 0 to -250 250 Co** 0 to 0.01 -23764 Oto -238 238 V** 0 to 0.1 -2352 Oto -235 235

*cm2/g. **Doubtful significance. Coef./s.d. ratio less than 2.

fluencing strength. Fe203 and Na20 also appeared

to have an effect on the strength gain and the

ratio, but not on the 7- and 28-day strengths

per se. The contributions of various independent variables to the compressive-strength-gain ratios were calculated from eq 3, table 7-42, and are presented in table 7-44 together with the cal- culated ranges of these contributions. Zr appeared

to be associated with higher strength gain ratio,

and Ti, Pb, and V were not highly significant. Increases in all other independent variables

appeared to be associated with lower strengthgain ratios.

Table 7-41. Frequency distribution of cements with respect

to slrenqth-giin ratio from 7 to 28 days of 1:2.75 {cement

to graded Ottawa sand) mortar cubes stored in water. Strength-gain ratio, SGR{1) = {28-day— 7-day) l7-day

Stren^'th -gain ratio

0 0.15 0.30 0.45 0.60 0.75 0.90 10.5 1.20 1.35 1.50 1.65 1.80 Tyye to to to to to to to to to to to to to Total Cement 0.15 0.30 0.45 0.60 0.75 0.90 1.05 1.20 1.35 I.JO 1.65 1.80 1.95 Number of cements

I.... 3 27

12

34

4

15

12

15

2

18

2

1 20

1

1 828

68

3203

IS

lA.

II 1

'

1 10

7 2 1 1 1 IIA

III 4

2 4 IIIA i IV&

v

2 5 3 1 2 1 1

Total.. 6 15 35 58 40 27 8 1 2 1 1 199

5.13. Compressive Strength Gain from 7 Days

to 1 Year

The frequency distributions of the compressivestrength gain values from 7 days to 1 year for water-stored specimens made of the cements of the different types are presented in table 7-45.

In one instance the compressive strength at 1 year was less than at 7 days. Although there was

considerable overlapping obtained with the dif- ferent types, the cements classified as types IV

and V had a higher mean value than was obtained

with the other types. The average gain of each of the types of cements was previously presented

graphically in figure 7-1 but does not indicate the

spread of the individual values.

The results of plotting the compressive strength

gain from 7 days to 1 year for both water-stored

Table 7-42. Equations relating the compressive-strength-gain ratio, {28-day

Equation Note Const. C3A CaS CaO Si02 re203 S03 Na20

3...

3A.

3B.

4...

5...

6...

7-.

7A7B.

(')

(')

(')

(2) m

(')

(')

(')

(')

(-)

{')

(')

SGR(l)

s.d. SGR(l)

s.d. SGR(l)

s.d. SGR(l) (odd) = s.d. SGR(l)(even) = s.d. SGR(l)

s.d. SGR(l)

s.d. SGR(l)

s.d. SGR(l)

s.d. SGR(l) (odd) = s.d. SGR(l) (even) = s.d. SGR(l)

s.d.

= +1. 825

= (0.099)

= +2.055

= (0.103)

-- +2. 238

= (0.102) =+2.165

= (0.143) =+2.372

= (0.161)

= +2.304

= (0.116)

= +1. 870

= (0.650)

= +5. 100

= (0.792)

= +4.537

= (0.739)

= +3. 952

= (1.089)

= +5.695

= (1.073)

= +4.872

= (0.784)

-0. 0297

(0. 0036)

-0. 0179

(0. 0039

-0. 0218

(0. 0038) -0. 0237

(0. 0052) -0. 0206

(0. 0057) -0. 0221

(0. 0039)

-0. 0104

(0. 0019) -0. 0128

(0. 0018) -0.0124

(0. 0017) -0. 0108

(0. 0021)

-0. 0158

(0. 0028)

-0. 0128

(0. 0017)

-0. 0458

(0. 0104)

-0. 0772

(0. 0108) -0.0692

(0. 0101)

-0. 0607

(0. 0150) -0.0903

(0. 0151)

-0. 0750

(0. 0106)

+0. 0853

(0. 0092)

+0. 0510

(0. 0102) +0. 0567

(0. 0095)

+0. 0536

(0. 0121) +0. 0702

(0. 0148)

+0. 0607

(0. 0098)

+0. 0640

(0. 0164)

+0. 0354

(0. 0156)

+0. 0448

(0. 0145)

+0. 0699

(0. 0196) +0. 0137

(0. 0219)

+0. 0444

(0. 0149)

-0. 1309

(0. 0399) -0. 1353(0. 0645)

-0. 1226

(0. 0369) -0. 1724

(0. 0594) -0. 1009

(0. 0595) •-0. 0651

(0. 0776) -0. 1498

(0. 0509) -0.4021

(0. 1037) -0. 1569

(0. 0360) -0. 1725

(0. 0607)

-0. 1442

(0. 0409) -0. 1362

(0. 0377) -0. 1354

(0. 0596) -0. 1495

(0. 0509)

-0. 1557

(0. 0370)

-0. 1606

(0. 0625)

-0. 1884

(0. 0582) -0. 0616

(0. 0723) -0. 4619

(0. 1026) -0. 2017

(0. 0597)

1 169 cements; Avg=0. 5811; S.D. =0.2146. 2 85 cements. 3 84 cements. *Coef./s.d. ratio less than 1.

30
1-year compressive-strength gain as calculated

from eq 4 of table 7-46 are presented in table

7-48. Of the variables, increases in Loss and Zr

and possibly P appear associated with greater

strength gain, and increases in the others with

lower strength-gain values.

5.14. Compressive-Strength-Gain Ratio, (1 year -7 day)/7 day, (SGR(2)), for WaterStored Specimens

The frequency distributions of the 7 days to

1 year compressive-strength-gain-ratio values obtained with the different types of cement are presented in table 7-49. The cements classified as types II, rV, and V had the higher values although

there was considerable overlapping of the values

obtained with the different types.

Equations relating the compressive-strengthgain ratios obtained with the AE+NAE cements,

and with the NAE cements alone, are presented

in tables 7-50 and 7-51 respectively. The use of the independent variables in eq 1, table 7-50

resulted in a highly significant reduction in the

S.D. value. The use of additional commonly

determined variables, as in eq 2 resulted in a further significant reduction in the S.D. value,

and use of the trace elements and Loss, as in eq 3, resulted in a further significant reduction in the

S.D. value. Similar comparisons may be made

with eqs 5 and 6, or with eqs 6 and 7, where the

major oxides were included as independent variables, and the reduction of the S.D. values were

in both instances highly significant (see table

7-75). In eqs 3 and 7, however, air in 1:4 mortar,

Rb, and P did not show evidence of being highly — 7 daij) 17-day, water-stored, for AE-\- NAE cements to various independent variables

KiO APF WAGN. Zr Cr Ti Pb v Loss S.D.

-0. 000137

CO. 000023)

-0. 000097

CO. 000027)

-0. 000122

CO. 000025)

-0. 000137

CO. 000034)

-0. 000092

CO. 000041)

0. 1475

-0.1634

(0. 0544) -0. 1707

(0. 0506) -0. 1926

(0. 0689)

-0. 1108

CO. 0809) -0.1638

CO. 0520)

0.1365

+0. 761

CO. 242) *-0. 097

CI. 286)

+1. 026

CO. 280)

+0. 917

CO. 251)

-7. 213

C2. 431)

-5. 616

C3. 422) -10.232

C3. 843) -7. 873

C2. 335)

-0. 1694

CO. 0901) •-0.0947

CO. 1409) •-0. 1762

CO. 2130) -0. 1910

CO. 0917)

-2. 276

CI. 608) -2.258

CI. 745) •-0. 861

C5. 431) -2.394

CI. 642)

-0. 959

CO. 620) -1. 246

CI. 133) •- 0.675

CO. 821)

0.1238

0. 1185

0.1299

-0. 000203

CO. 000052) -0. 0264CO. 0203) 0.1264

-0. 000122

CO. 000022) -0. 000114

CO. 000024) -0. 000125

CO. 000023) -0.000121

CO. 000029) -0.000114

CO. 0o0u36)

0. 1455

-0. 2496

CO. 0583) -0. 2290

CO. 0543) -0.2425

CO. 0728) -0. 1707

CO. 0822)

-0. 2374

CO. 0561)

0. 1322

+0. 795

CO. 237)

* +0.098

CI. 243)

+1. 070

CO. 268) +0.988

CO. 245)

-7. 659

C2. 275) -6. 610

C3. 061) -10.613

C3. 531) -6. 780

C2. 308)

-0. 1673

CO. 0876) -0. 1312

CO. 1266) *-0. 0870

CO. 2077)

-0. 1787

CO. 0896)

-2.386

CI. 574) -2.520

CI. 620) +0. 359

C5. 204) -2. 450

CI. 599)

0. 1215

0. 1137

0. 1249

-0. 000209

CO. 000047) -0.0509

CO. 0204) 0.1232

l'

and air-stored specimens versus various independent variables are presented in figure 7-4.

Of the various independent variables, for which

relationships were plotted for the water-stored

specimens, only CaO, MgO and fineness had

quadrant sum absolute values less than 1 1

.

Equations relating the 7-day to 1-year compressive-strength gain of AE+NAE cements to various independent variables are presented in

table 7-46. The use of only 3 independent variables and the constant as in eq 1 resulted in a

highly significant decrease in the S.D. value.

The addition of 3 more commonly determined

variables as in eq 2 resulted in a further significant

decrease in the S.D. values. The further inclusion

of 4 trace elements as in eq 4 also resulted in a

significant decrease in the S.D. value although

two of the latter, P and Rb, did not appear to be

highly significant. Similar compaiisons may be

made for eqs 6 and 7 or 7 and 8 (see table 7-75)

.

C2S was used in eq 3 and resulted in a slightly

higher S.D. value than when C3S was used as in

eq 2. In eqs 5 and 6, the use of Fe203 instead of AI2O3 also resulted in a lower S.D. value. In

eqs 4A, 4B, 8A, and 8B for the "odds" and

"evens" in the array of cements P and Rb had

coef./s.d. ratios less than one in eqs 4B and 8B.

The equations for the NAE cements presented

in table 7-47 were consistent with those of table

7-46 where the AE cements were included except

that in the "odds" and "evens" there were

instances in eqs 4B and 8B where the coef./s.d.

ratios of Loss, Zr, P, and Ti were less than one. The contributions and ranges of contributions

of the independent variables of the 7-day to
Table 7-43. Equations relating the compressive-strength-gain ratio, (28-day

Equation Note

(')

(')

(')

(2)

(')

(')

(1)

(')

(')

P)

(')

(')

SGR(l)

s.d. SGRd)

s.d. SGR(l)

s.d. SGR(l) (odd) = s.d. SGRd) (even) = s.d. SGR(l)

s.d. SGRd)

s.d. SGRd)

s.d. SGRd)

s.d. SGRd) (odd) = s.d. SGRd) (even) = s.d. SGRd)

s.d.

Const.

= +1. 809

= (0.104) =+2.035

= (0.110)

= +2.220

= (0.109)

= +2. 122

= (0.145)

= +2.398

= (0.183)

= +2.291

= (0.126)

= +1. 819

= (0. 690;

= +4. 990

= (0.848)

= +4.461

= (0.793)

= +5.076

= (1.099)

= +4.0

= (1.298)

= +4. 752

= (0.839)

CsA

-0. 0292

(0. 0037) -0. 0180

(0. 0041) -0. 0213

(0. 0040) -0. 0212

(0. 0059) -0. 0190

(0. 0058) -0. 0218

(0. 0041)

C3S

-0. 0103

(0. 0020)

-0. 0126

(0. 0019)

-0. 0124

(0. 0018) -0. 0119

(0. 0022)

-0. 0146

(0. 0032)

-0. 0129

(0. 0018)

CaO

-0.0440

(0. 0109) -0. 0751

(0. 0115) -0. 0676

(0. 0108) -0. 0753

(0. 0146) -0. 0624

(0. 0183) -0. 0731

(0. 0113)

SiOj

+0. 0817

(0. 0096)

+0. 0488

(0. 0106)

+0. 0549

(0. 0099) +0. 0496

(0. 0137)

+0. 0587

(0. 0151)

+0. 0597

(0. 0103)

Fe203

+0. 0695

(0. 0173)

+0. 0394

(0. 0167)

+0. 0475

(0. 0155)

+0. 0319

(0. 0235)

+0. 0567

(0. 0234)

+0. 0477

(0. 0160)

SO3

-0. 1258

(0. 0416) -0.1209

(0. 0388) -0. 1243

(0. 0629) -0. 1600

(0. 0556) -0.1557

(0. 0379)

-0. 1396

(0. 0427) -0. 1331

(0. 0395) -0. 1545

(0. 0630) -0. 1401

(0. 0573) -0. 1535

(0. 0390)

1 157 cements; Avg=0.5847; S.D. =0.2150. ' 79 cements. ' 73 cements. •Coef./s.d. ratio less than 1.

significant. In the equations for the "odds" and

"evens" in the array of cements, eqs 3A, 3B, 7A

and 7B it may be noted that the air content and

the trace elements had coef./s.d. ratios less than one in one or both of the equations.

The equations presented in table 7-51 for the

NAE cements alone are consistent with those

presented in the previous table where the AE

cements were included.

The contributions and ranges of contributions

of the various independent variables to the

strength-gain ratio as calculated from eq 3 of table 7-50 are presented in table 7-52. Increases

in Zr, and Loss with possibly air content were

associated with higher compressive-strength-gain

ratios, and increases in the other variables associated with lower strength-gain ratios. Kb and P

were not highly significant.

5.15. Compressive Strength Gain From 28

Days to 1 Year (SG(3))

The frequency distributions. of the compressivestrength-gain values from 28 days to 1 year for the

different types of cement are presented in table

7-53. Eight of the cements had lower compressive

strength values at 1 year than at 28 days. Other

cements had a large strength gain during this period.

T.vBLE 7-44. Calculated contribution of independent vari- ables to compressive strength gain ratio, (28-day —7-d/i/)l

7-day, (SGR(l)), of 1:2.75 (cement to graded Ottawa sand) mortar cubes, water-stored, and the calculated ranges of such contributions

Inde- pendent

variable

Range of variable

(percent)

Coefficients from eq (3) of table 7-42

Calculated

contribution to SGR(l)

Cal- culated range

of contri- bution

to SGR(l)

Const. = +2. 238 C3A 1 to 15 -0. 0218 -0. 022 to -0. 327 0. 305 C3S 20 to 65 -0. 0124 -0. 248 to -0. 806 0.558 SO3 . 1.2 to 3.0 -0. 1226 -0. 147 to -0. 368 0. 221 NaaO 0 to 0.7 -0. 1724 0 to -0. 121 0. 121 K2O 0 to 1.1 -0. 1707 0 to -0. 188 0.188 APF *2500 to 5500 -0. 000122 -0. 305 to -0. 671 0. 366 Zr 0 to 0.5 +0. 761 0 to +0. 381 0.381 Cr 0 to 0.02 -7. 213 0 to -0. 144 0. 144 Ti** 0 to 1.0 -0. 1694 0 to -0. 169 0.169 Pb" i, 0 to 0. 05 -2. 276 0 to -0. 119 0.119 V" 0 to 0.1 -0.959 0 to -0.096 0. 096

'cmVg.

**Doubtful signilicance. Coef./s.d. ratio less than 2.

Equations relating the compressive-strength

gain of the AE +NAE cements to various in- dependent variables are presented in table 7-54.

The use of the independent variables in eq 1 resulted in a significant reduction in the S.D.

value. The use of the additional commonly

determined variables in eq 2 resulted in a further

32
— 7-day) 1 7-day, water-stored, for NAE cements to various independent variables

APF WAGN. Zr Cr Ti Pb V Loss 8.D.

-0. 000136

(0. 000025) -0. 000098

(0. 000028)

-0. 000119

(0. 000027)

-0. 000112

(0. 000037) -0. 000105

(0. 000043)

0. 1490

-0. 1643

(0. 0572)

-0. 1733

(0. 0536)

-0. 1094

(0. 0792)

-0. 2575

\yj. KJl w

f

-0. 1649

(0. 0549)

0. 1392

+0.763

(0. 250)

+1. 319

(0. 656) +0. 681

(0. 286)

+0. 917

(0. 259)

-6. 650

(2. 564)

1.593

(4. 212) -11.996

(3. 685) -7. 180

(2 4741

-0. 2042

(0. 0957) -0. 2454

(0. 1260) *-0. 0993

(0. 2137) -0. 2248

(0. 0974)

-2.246

(1. 652) -2.093

(1. 908) *-3. 528

(4. 614) -2.344

(1. 688)

-0. 857

(0. 643) -1.743

(1. 084) •-0. 408-

(0. 855)

0.1270

0.1280

0. 1302

-0. 000198^

(0. 000055) -0. 0268

(0. 0216) 0.1296

-0. 000122

(0. 000023) -0. 000115

(0. 000026) -0. 000125

(0. 000024) -0. 000112

(0. 000033)

-0. 000127

(0. 000039)

0. 1471

-0. 2503

(0. 0615) -0. 2318

(0. 0577) -0. 2077

(0. 0854)

-0. 2730

(0. 0868)

-0. 2347

(0. 0594)

0. 1349

+0. 785

(0. 244) +1. 398

(0. 634) +0.685

(0. 285) +0. 980

(0. 254)

-7. 079

(2. 395) *-2.395

(3. 819)

-11. 411

(3. 561) -6. 173

(2. 445)

-0. 1947

(0. 0931)

-0. 2817

(0. 1162) *-0. 0779

(0. 2198)

-0. 2055

(0. 0956)

-2.331

(1. 616) -2. 856

(1. 832) *-3. 142

(4. 649)

-2. 410

(1. 648)

0.1245

0. 1240

0.1304

-0.000207

(0. 000050) -0. 0505

(0. 0217)

0. 1266

Table 7-45- Frequency distribution of cements with respect to compressive strength

change from 7 days to 1 year of 1:2.75 {cement to graded Ottawa sand) mortar

cubes, water-stored

Compressive strength changes, psiXlO-3 Type -0.5 0 +0.5 +1.0 +1.5 +2.0 +2.5 +3.0 +3.5 +4.0 +4.5 +5.0 +5.5 Cement to to to to to to to to to to to to to Total

0 +0.5 +1.0 +1.5, +2.0 +2.5 +3.0 +3.5 +4.0 +4.5 +5.0 +5.5 +6.0 Number of cements

I 3 16 23 21 14 3 1 81 lA 1 3 1 2 1 8

11 1 1 13 12 19 11 10 1 68 IIA _ 3 3

III 4 3 6 2 1 2 20 IIIA.-.. 1 1 1 3 rv& v_ 2 3 3 6 1 15

Total. 1 1 4 7 27 27 41 29 28 15 16 1 1 198

significant decrease in the S.D. value, and by

use of three trace elements as in eq 3 a further

significant decrease in the S.D. value was attained

although two of the' three, P and Ti, did not

appear highly significant. Similar reductions were

obtained in eqs 5, 6, and 7 where the major

oxides were used in the equations (see also table

7-75). In the equations for the "odds" and

"evens" in the array of cements, C4AF, P, and Ti

; had coef./s.d. ratios less than 1 in one or both

I of the groups. The differences of the coefficient

! and the coef./s.d. ratio of APF in eqs 1, 2, and

3, or in eqs 4, 5, and 6 indicate, to some extent,

as in previous tables the interrelation of this variable with other variables. This will be dealt

with more fully in the discussion (subsection 6). The equations for the NAE cements alone

(table 7-55) are consistent with those in table

7-54 where the AE cements were included ex- cept that the use of the additional variables

in eq 3, table 7-55 resulted in a reduction of the

S.D. value which was significant only at the

five percent probability level.

33
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to OS

i-c'd

TP "O I^CO tH CO

r>- o o w 1-H CD O ^ OS"^ 1—I N do

I ^

O COooco

I ^

CO CO to 00 TP OS CO CO 5S £2S

CO--'

I I

CO CO

(N OS

t>. Oi "OS CD 0*0 I~-00 Tp t;; O O od 00

CO co_ 23 i3 ~ ' ~ + + + +

CD T*« od 00 o »o ic- - +

00 CD dt^' ^ CD

I 1 O 00

t-^Tp' T

ot^

od ^" od TP

lO C*3

7

+

II II +

II II

OS to

CO CM

CO 00 O CO o ^

O CO +^

II II

I II

O-d Otj O'O 0-6 CO 0-6 O'd 0-6 Mm 03^ CQtn Mw 02m oom 03 M CO

35
Table 7-48. Calculated contribution of independent variables

to compressive strength in psi gain from 7 days to 1 year, SG{2), of 1:2.75 {cement to graded Ottawa sand) mortar

cubes, water-stored, and calculated ranges of such contri- butions

Calcu- Inde- Coefficients Calculated lated pendent Range of variable from eq (4) contribution range of variable (percent) of table 7-46 to SG(2) contri- bution

to SG(2)

Const. = +10168 CsA - 1 to 15 -167.0 -167 to -2605 2338 C3S OA f/\ fir: ZD 10 DO —Do. 1 — iz/i to — OflK7 ZOD/ NajO 0 to 0.7 -1187 Oto -831 831 K2O 0 to 1.1 -1079 Oto -1187 1187 APF *2500 to 5500 -0. 5626 -1407 to -3094 1687 Loss.- - -. 0.3 to 3.3 +169.

1

+51 to +558 507 Zr 0 to 0.5 +2860 0 to +1430 1430 P" 0 to 0.5 +671.

9

Oto +336 336 Rb** 0 to 0.01 -31953 Oto -320 320 Ti 0 to 1.0 -976 Oto -976 976

*cm2/g. **Doubtful significance. Coef./s.d. ratio less than 2.

Table 7-49. Frequency distribution of cements with respect

to strength-gain ratio from 7 days to 1 year of 1:2.75 {cement to graded Ottawa sand) mortar cubes stored in water

Strength-gain ratio S G R(2) = (1-year—7-day) /7-day

Strength-gain ratio

-0.3 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0 3.3 Type Cement to to to to to to to to to to to to to Total

0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0 3.3 3.6 Nymber of Cements

J 22 36 20 3 81 lA 8

•1 3 3 1 II 1 7 21 "21 12 4 1 1 68 IIA__ 3 3 Ill 1 8 7 2 2 20 IIIA 1 1 1 3 rv^& V 5 2 5 1 1 1 15 Total 1 9 32 52 46 29 15 9 1 1 1 1 1 198

Table 7-50. Equations relating the compressive-strength-gain ratio {1-year — 7-day)/

Equation Note Const. C3A C3S CaO SiOs FeiOj NajO

SGR(2)

s.d. SGR(2)

s.d. SGR(2)

s.d. SGR(2) (odd) = s.d. SGR(2) (even) = s.d. SGR(2)

s.d. SGR(2)

s.d. SGR(2)

s.d. SGR(2)

s.d. SGR(2) (odd) = s.d. SGR(2) (even) = s.d. SGR(2)

s.d.

= +3. 925

= (0.170)

= +4.378

= (0.168)

= +4.561

= (0.169)

= +4.456

= (0.245)

= +4.717

= (0.261)

= +4. 818

= (0.190)

= +3. 863

= (1.102)

= +8.720

= (1.290)

= +7. 765

= (L 299)

= +6.650

= (1.824)

= +8.921

= (2.010)

= +8.0

= (L225)

-0. 0874

(0. 0063) -0. 0297

(0. 0033) -0. 0665

(0. 0065) -0. 0337(0. 0030)

-0. 0682

(0. 0062) -0. 0353(0. 0028) -0. 0733

(0.0088) -0. 0353(0. 0038) -0. 0595

(0. 0097) -0. 0354(0. 0045) -0.0735

(0. 0065) -0. 0358

(0. 0027) -0. 1341

(0. 0179) -0. 1814

(0. 0179) -0. 1716

(0. 0179) -0. 1628

(0. 0242) -0. 1779

(0. 0287) -0. 1778

(0. 0171)

+0. 2682

(0. 0162)

+0. 2182

(0. 0171) +0. 2310

(0. 0170) +0.2448

(0. 0242)

+0. 2118

(0. 0260)

+0. 2450

(0. 0165)

+0. 1269

(0. 0276)

+0. 0889

(0. 0261)

+0. 1062

(0. 0254) +0. 1252

(0. 0334)

+0. 0807

(0. 0424)

+0. 1124

(0. 0250)

-0. 3848

(0. 1099) -0. 5075

(0. 0923)

-0. 4361

(0. 1049) -0.4223(0. 0955) -0.3235

(0. 1291) -0. 2791

(0. 1409) -0. 6152

(0. 1948) -0. 5328

(0. 1441)

-0. 4471

(0. 1045) -0.4139

(0. 0949)

-0. 4038

(0. 1057) -0. 5967(0. 0975) -0. 4399

(0. 1032) -0. 4805

(0. 1025) -0. 3332

(0. 1288) -0. 3191(0. 1590) -0. 5806

(0. 1916) -0. 6097(0. 1499) -0.4499

(0. 1011) -0. 4738(0. 0996)

1 174 cements; Avg=0.9842; S.D. =0.4698. 2 87 cements. *Coef./s.d. ratio less than 1.

36
The contributions of the various independent

variables to the compressive-strength gain between 28 days and 1 year for the water-stored

specimens were calculated from eq 3 of table 7-54

and are presented in table 7-56 together with the

calculated ranges of these contributions. Increases

in Loss, V, and possibly P, appear to be associated

with higher compressive-strength-gain values,

and increases in the other variables appear as- sociated with a decrease in the strength-gain

values. Ti was not highly significant. C3A, C3S,

and Loss appear to have the dominant role with

respect to this property.

5.16. Compressive-Strength-Gain Ratio (1 Year -28 Day) /28 Day, SGR(3), for Specimens Stored in Water

The frequency distributions of the 28-day to 1-year compressive-strength-gain-ratio values for

the different types of cement are presented in table 7-57. Although there is considerable overlapping, the median values for the different types

of cement increase from type III, to type I, to type II, to types IV and V.

Equations relating the compressive-strengthratio values to combinations of mdependent variables are presented in table 7-58 for the AE-|-NAE

cements, and in table 7-59 for the NAE cements

alone. The use of some commonly determined

variables, as in eqs 1 and 5, resulted in highljjr

significant reductions in the S.D. values. Additional commonly determined independent variables added in eqs 2 and 6, resulted in a further

significant reduction in the S.D. values, but the

addition of two trace elements in eqs 3 and 7 did not result in a reduction of the S.D. value

significant at the five percent probability level. Similar results were obtained for the NAE

7-day, water-stored, for AE-\- NAE cements to various independent variables

S03 WAGN. APF Air 1:4 mortar Zr Bb Ti P Loss S.D.

-0. 000210

(0. 000041)

-0. 000199

(0. 000044)

-0. 000231

(0. 000044)

-0. 000177

(0. 000056) -0.000287

(0. 000073)

0. 2576

-0. 1298

(0. 0664)

-0. 1626

(0. 0628)

-0. 2127

(0. 0988) -0. 1671

(0. 0915) -0. 1730

(0. 0576)

+0. 0110

(0. 0050)

+0. 0095

(0. 0048)

+0. 0106

(0. 0067)

+0. 0106

(0. 0073)

+0. 0082

(0. 0048)

0.2288

+1.232

(0. 425)

+1. 269

(0. 452) •+1.234

(1. 248) + 1.599

(0. 415)

-12.79

(9. 89)

-30. 25

(13. 96)

•+6. 38

(14.81) -19.39

(9. 89)

-0. 3333

(0. 1443)

-0. 4559

(0. 2335)

-0. 2520

(0. 2210)

-0. 3554

(0. 1431)

+0. 2015

(0. 1536)

+0. 4628

(0. 2568)

•+0. 0267

(0. 2017)

+0. 2266

(0. 1533)

+0. 1010

(0. 0350)

+0. 0967

(0. 0489)

+0. 1152

(0. 0532)

0. 2138

0. 2071

0.2238

-0. 000452

(0. 000084)

0. 2139

-0. 000160

(0. 000037)

-0.000215

(0. 000040)

-0. 000241

(0. 000041)

-0. 000193

(0. 000053)

-0.000284

(0. 000071)

0. 2492

-0. 0752

(0. 0676) -0.0756

(0. 0645) -0. 1065

(0. 1011) -0. 1019

(0. 0950) -0. 0977

(0. 0614

.

+0. 0077

(0. 0050)

+0. 0071

(0. 0048)

+0. 0092

(0. 0067)

*+0. 0066

(0. 0073)

+0. 0055

(0. 0048)

0. 2216

+1. 270

(0.421)

+1. 301

(0. 448) +1. 191

(1.258) +1. 581

(0. 406)

-10. 61

(9. 71) -27.37

(13. 49)

•+8. 31

(14. 75) -17.00

(9. 66)

-0. 2873

(0. 1425)

-0. 4115

(0. 2289) •-0. 1858

(0. 2220)

-0. 2951

(0. 1404)

+0. 2137

(0. 1513)

+0. 4951

(0. 2548)

*+0. 0237

(0. 2002)

+0. 2488

(0. 1495)

+0. 0736

(0. 0367)

+0. 0817

(0. 0521) +0. 0710

(0. 0564)

0.2108

0. 2052

0. 2221

-0. 000467

(0. 000077) 0.2092

37
Table 7-51. Equations relating the compressive-strength-gain ratio (1-year

Note m

(')

(I)

(')

(2)

(')

(1)

()

(')

{')

(2)

(')

SGR(2)

s.d. SGR{2)

s.d. SGR(2)

s.d. SGR(2) (odd) = s.d. SGR(2) (even) = s.d. SGR(2)

s.d. SGR(2)

s.d. SGR(2)

s.d. SGR(2)

s.d. SGR(2) (odd) = s.d. SGR(2) (even) = s.d. SGR(2)

s.d.

Const.

= +3. 912

= (0.179)

= +4.333

= (0.182)

= +4.619

= (0.185)

= +4. 350

= (0.262)

= +4.825

= (0.287)

= +4.797

= (0.211)

= +3.760

= (1.177)

= +8.846

= (1.372) =+7.900

= (1.379)

= +7. 926

= (2.023)

= +9.117

= (1.975)

= +8.022

= (1.308)

C3A C3S

—0. 0874

(0. 0066) -0. 0291

(0. 0034)

—0. 0656

(0. 0069) -0.0337

(0. 0031)

—0. 0663

(0. 0066) -0. 0356

(0. 0030)

-0. 0697

(0. 0096) -0. 0334(0. 0040) -0. 0640

(0. 0097) -0.0387(0. 0047) -0. 0725

(0. 0070) -0.0361(0. 0029)

CaO

-0. 1313

(0. 0188) -0. 1821

(0. 0189)

-0. 1723

(0. 0188) -0. 1720

(0. 0270) -0. 1889

(0. 0277) -0. 1777

(0. 0181)

Si02

+0. 2644

(0. 0169)

+0. 2139

(0. 0180)

+0. 2260

(0. 0180)

+0. 2203

(0. 0246)

+0. 2311

(0. 0275) +0. 2454

(0. 0173)

+0. 1342

(0. 0292) +0.0889

(0. 0276)

+0. 1064

(0. 0269) +0. 1147

(0. 0359)

+0. 0799

(0. 0435)

+0. 1124

(0. 0264)

NajO

-0. 3934

(0. 1203) -0. 5190(0. 0988) -0. 4475

(0. 1157) -0. 4274(0. 1011) -0. 3260

(0. 1444) -0. 4711

(0. 1484) -0. 7022

(0. 2038) -0.3284

(0. 1530) -0.4450

(0. 1153) -0. 4031(0. 1004)

-0. 4121

(0. 1152) -0.6154(0. 1045) -0. 4445

(0. 1137) -0.4901(0. 1093) -0. 3447

(0. 1435) -0. 5787(0. 1684) -0. 6962

(0. 1981) -0. 3921(0. 1577) -0.4111

(0. 1040) -0. 4518(0. 1046)

' 162 cements; Avg=0.9923; S.D. =0.4746. 2 81 cements. *Coef./s.d. ratio less than 1.

T.\BLE 7-52. Calculated contribution of independent variables

to compressive-strength-gain ratio, {1-year— 7-day) 17-day,

{SGR{2)), of 1:2.75 {cement to graded Ottawa sand) mortar cubes, water-stored, and the calculated ranges of such contributions

CalcuInde- Range of Coefficients Calculated lated pendent variable from eq (3) contribution range of variable (percent) of table 7-50 to SGR{2) contri- bution to

f

SGR(2)

Const. = +4. 561 C3A 1 to 15 -0. 0682 -0.068 to -1.023 0. 955 CsS 20 to 65 -0. 0353 -0.706 to -2.295 1.589 Na20 0 to 0.

7

-0. 4361 0 to -0.305 0. 305 K2O 0 to 1.

1

-0. 4223 0 to -0.465 0. 465 SO3 1. 2 to 3.

0

-0. 1626 -0. 195 to -0.488 0.293 APF *250O to 5500 -0. 000231 -0.578 to -1.271 0.693

Air, 1:4 mortar'*. 1 to 21 +0. 0095 +0. 010 to +0. 200 0. 190 Zr 0 to 0.

5

+1.232 0 to +0. 666 0. 666 Rb" 0 to 0. 01 -12.79 0 to -0.128 0. 128 Ti 0 to 1.0 -0. 3333 0 to -0.333 0.333 P" 0 to 0.

5

+0. 2015 0 to +0. 101 0. 101 Loss. 0. 3 to 3. 3 +0. 1010 +0. 030 to +0. 333 0.303

•cmVg. "Doubtful significance. Coef./s.d. ratio less than 2.

Table 7-53. Frequency distribution of cements with respect

to compressive strength change from 28 days to 1 year of 1:2.75 {cement to graded Ottawa sand) mortar cubes, water-stored

Type

Cement

Compressive strength change, psiXlO-'

Total

-1.0

to -0.5

-0.5

to0

0

to +0.5

+0.5

to +1.0

+1.0

to +1.5

+1.5

to +2.0

+2.0

to +2.5

+2.5

to +3.0

+3.0

to +3.5

+3.5

to +4.0

+4.0

to +4.5

Number of cements

I 1 21

12

33

5

7

15

1

18

1 18

12

13

7

1 25

1

1 81

8

68

3

20

3

15

lA...

II 11 5 IIA

Ill 2 4

1 5 2 IIA IV&V 3 4 2 1 1 1

Total 2 6 29 52 44 37 18 7 1 1 1 198

38
— 7-day) 1 7-day, water-stored, for NAE cements to various independent variables

SOi WAGN. APF Air 1:4 mortar Zr Rb Ti P liOSS S.D.

-0. 000216

(0. 000043) -0. 000206

(0, 000047) -0.000234

(0. 000045)

-0. 000217

(0. 000059) -0. 000261

(0. 000076)

0.2607

-0. 1258

(0. 0700)

-0. 1623

(0. 0661)

-0. 1605

(0. 1159)

-0. 1671

(0. 0888)

-0. 1769)

(0. 0615)

+0.0204

(0. 0117)

+0. 0186

(0. 0113)

+0. 0252

(0. 0162) »+0. 0064

(0. 0176)

+0. 0136

(0. 0114)

0.2341

+1.281

(0. 442) +1.247

(0. 456) -3. 629

(3. 101) +1. 625

(0. 431)

-14.87

(10. 26) *-9. 12 (14.03)

-17. 37

(15. 75) -21. 16

(10. 29)

-0. 3473

(0. 1525)

-0. 6125

(0. 2416)

•+0. 1419

(0. 2887) -0. 3665

(0. 1517)

+0. 1693

(0. 1605) +0. 4818

(0. 2569)

•+0. 1016

(0. 2152) +0. 2066

(0. 1606)

+0. 0956

(0. 0369)

+0. 1042

(0. 0495)

+0. 0796

(0. 0582)

0. 2187

0. 2106

0.2248

-0. 000453

(0. 000090)

0. 2195

-0. 000165

(0. 00040)

-0. 000223

(0. 000043)

-0. 000246

(0. 000043) -0. 000224

(0. 000055) -0.000268

(0. 000073)

0.2583

-0. 0788

(0. 0712) -0. 0775

(0. 0680) *-0.0957

(0. 1158) •-0. 0741

(0. 0934)

-0. 0880

(0. 0635)

+0. 0156

(0. 0114) +0. 0140

(0. 0112)

+0. 0218

(0. 0161) *-0. 0019

(0. 0172)

0.2271

+1. 294

(0. 439)

+1. 243

(0. 451) -4. 191

(3. 043) +1. 544

(0. 419)

-12. 11

(10. 11) •-8. 62

(13. 56) •-10.75

(15. 90) -18.23

(10. 07)

-0. 2891

(0. 1512)

-0. 5891

(0. 2347) •+0. 2686

(0. 2838)

-0. 3059

(0. 1990)

+0. 1902

(0. 1586) +0. 5313

(0. 2537)

*+0. 0952

(0. 2126)

+0. 2595

(0. 1541)

+0.0681

(0. 0386)

+0. 0830

(0. 0507) *+0. 0271

(0. 0629)

0.2164

0.2073

0. 2220

-0. 000480

(0. 000083)

0. 2152

cements in table 7-59 (see also table 7-75).

Equation 5 in table 7-58 and also in table 7-59

indicates APF had a coef./s.d. ratio less than 1, but the variable was highly significant in eqs 6

and 7. In both of these tables, in the equations

for the "odds" and "evens" in the array of

cements, eqs 3A, 3B, 7A, and 7B, both P and Co

had coef./s.d. ratios less than 1 in one or the other

of the smaller groups. Also, in table 7-58, the

C4AF had a coef./s.d. ratio less than 1 in eq 3B.

The contributions of the different variables to the strength-gain-ratio values were calculated

from eq 3 of table 7-58 and are presented in table

7-60 together Avith the calculated ranges of these

contributions. The C3A and C3S were the dominant variables with respect to the calculated

range of possible contribution to the compressivestrength-gain-ratio values.

5.17. Compressive Strength Gain From 28

Days to 10 Years

The frequency distributions of the compressivestrength-gain values from 28 days to 10 years of water-stored specimens of the different types of

cement are presented in table 7-61. Fifty-five of

the 169 cements had lower compressive strength

values at 10 years than they had at 28 days. Only

5 of these Avere classified as type II, the others

being of types I or III. There was a broad distribution of strength-gain values Avithin each of the

type classifications. Equations relating the compressive-strength

gain from 28 days to 10 years to various combinations of independent variables are presented in table 7-62 for the AE +NAE cements, and in table 7-63 for the NAE cements. Using 3 com- monly determined variables and a constant as in eq 1 of table 7-62, resulted in a highly significant

39
O PO CO ^

c6oi CO to

CO t-* CO

to CO

+ +

CO CM

crj oi

"3^

CO»-i

CO O Tt« CI +-'

00 O OS-X9*

TjJ GO od o CO CO ^

lO CM

1

t-, 00 »H CO co^ -^r^

4-

O Ol

CO o co^

CO 00

CO r—

CO o CO o ^ ^ O O o o

I - 1

CO eo o o o o o c,, o OS

I o o

»o o o> O ic 00 O CO CO -sj w o CO iO CD t-H CO ^ CO --' OS iM

I w I ^ I

CO ^ ^ to ^ CI CO Ol

CO C-l

00 r-" IC CO O CO CI CI cog

CO

CO "-' t^ci

oi ^ ^ ci CO CI CO

CD »0 CI l>-

CO 7""

iC 00

OJ 00 CD ui ^ ^ .-H ^ CI ^

^ CD Ci CO CI + +

CO +

CD

oi ic 7""

I>. CD iC »0 00 O

r-; 1-t CO o 1-1 ci

TP CO CO CO coco +

t^CO

iO Ot^ CDt^ o t— oo Tt< Tj* i-H .-HO CI cio coco t^oo cjt^ o6«D CDd iOi-f .-( t-H d lO CI

I w I ^ 1 J

I

-H C3 coo ^OD oo GO coco OSl>- COCO TJ4 lO CDCO

oi<o go»o oi>o ic oi TP' Tjl ^

I I I I I

*oci o CO oo t^O CO^

od-^ co-^" CO'-' ^ci 00^ lO ^ lO CI CO CI 7"" 7"" 7"" 7^

COCJ

CO CO

CD CO

CO p St

CJ CJ SCICI

.-H CI Tj* coo

II II II

lO CI QO »0 CON +

' Tf CI

II II II

O-o O-d Ots O-o Mm Mw Mm Mm O'O O'O O-o Ot) O'O Mm Mm Mm Men Mm
>

CO O 1- (N CTJ r^i^ O i-ttO OICC

CO o

3 CO Tt< to

O CO lO CO a>co

1—1 O Oi iC CO lO

00 31 00 O 00

OO

r-^co ao'^ f^'s cow CO^ CO"- + + + +-

CO CO Oi r- <-< GO r-^ CO OoQ

O 00 ^00 TP 00 . -HO CO O CO o

, _- «o .-I to i-H OS

to CO o OS o c — «5— o o CO

QO O 00 to OO m GOC^ f-« rH OO --HO (NO (NO "~ ^ o o o o do O O O O o o

I ^ o o

I ^

GO CO 0>

00 00 CO

CO CD o o

r^oi co^ r-^i-H mo r-o> 1—io> .-ho

tO(M iC—' Tj<(M t^CO

I - I

I ~-

I ^

CO o

CO iri

00b- OSIM .-t 00*0 O .—• O'-' to lO (N CO

COi^J tOC^

b-tO CDi-H CI'C rHr

(Ni-H coo OC

CO C-l CD CM tOOi oO ^

iC OS

to bC-1 iC

CO CO

01 00

CO QO

C3S CO 7^ O CO

I

CO CO

I

to OS OS CO i-H + +

to b» 00 00

OO CO »o

St-J IC OS 00 OS iC

r~. CO lo CM os^ (M CO o>c2

OOCO l>.i-i OO (M O CO

oi CO OS CO d CO l> Tt* o

OS OS

00

CN "I to «5 ^ CO d »c

c-i OO -n^cc

Oi-^ to TJ4

II II + +

0<N OCD

to CO LQ r- to^ co^ + +

II II II II II

OS OS

OS^ CO

li II

CO o lO CO

OS OS

(M to

»o to

to t-

(M +^

II II

00 rH

1-1 1>- OOO

OS t--

i-( OS

CO +^

II II

O-d Ot! 0*0 Ox) O'O

aim COM CBtn Min Moj 03 m en m

3

a"
Table 7-56. Calculated rontribufion of indevendent vari- ahles to comvresswe strenoth in vsi qain from 28 davs to

1 year, SG(3), of 1:2.75 (cement to graded Ottawa sand) mortar cubes, water-stored, and the calculated ranges of such contributions

Independent

variable Range of variable (percent)

Coefficients from eq (3)' of table 7-54Calculated

contribution to SG(3)

Calculated range of

contri- bution toSG(3)

Const. =+6463 C3A . . — 1 to 15 —153. 0 —153 to —2295 2142 CsS 20 to 65 -49. 34 -987 to -3207 2220

1 to 16 -47. 76 -48 to -764 716 NajO 0 to 0.

7

= 615.8 Oto -431 431 K2O 0 to 1.

1

-653.9 Oto -719 719 APF •2500 to 5500 -0. 3145 -786 to -1730 944 Loss 0. 3 to 3.

3

+349. 5 +105 to +1153 1048 P" 0 to 0.

5

+546.3 Oto +282 282 Ti'» 0 to 1.

0

-443. 0 Oto -443 443 V 0 to 0.

1

+4796 Oto +480 480

*cmVg.

**Doubtful significance. Coef./s.d. ratio less than 2.

Table 7-57. Frequency distribution of cements with respect

to strength-gain ratio from 28 days to 1 year of 1:2.75 {cement to graded Ottawa sand) mortar cubes stored in water

[Strength-gain ratio, SGR(3) = (l-year-28-day)/28-day]

Type cement

Strength-gain ratio

Total

-0.15

to

0

0

to

0.15

0.15 to

0.30

0.30 to

0.45

0.45 to

0.60

0.60 to

0.75

0.75 to

0.90

0.90 to

1.05

1.05 to

1.20

1.20

to

1.35 Number of cements

I _ lA

1 37

15

31

524

13

2

112

24

12

1 81

1 68

320

3

15

IIIIA.

13

1 2

III 6

1 9 IIIA IV &V

Total 52

2

68

4

44

4

18

2

5

1

1

1

1

1

8 1 198

reduction in the S.D. value. By using 3 additional

commonly determined variables, Na20, K2O and

Loss in eq 2, a further highly significant reduction

in the S.D. value was attained, and by use of the

trace elements in eq 3, the S.D. value was again

reduced by a significant amount, although 4 or 5

of the variables in eqs 3 and 7 do not show strong

evidence of significance (see also table 7-75). A

similar series of relationships using the oxides are presented in eqs 5, 6, and 7. Equations calculated

for the "odds" and "evens," eqs 3A, 3B, 7A, and

7B, indicated that K2O, APF, and each of the

trace elements had coef./s.d. ratios less than 1 in one or the other of the smaller groups of cements.

The use of the fineness values determined by the

two methods, (eqs 3 and 4, or eqs 7 and 8) resulted

in S.D. values which were nearly the same. An analogous series of equations for the NAE

cements are presented in table 7-63. The series of equations, 1, 2, and 3, or 6, 7, and 8 each indicate a progressive significant reduction in the S.D.

values (see also table 7-75). Equatious calculated

for the "odds" and "evens" in the array of cements

indicated a number of independent variables with

coef./s.d. ratios less than one, as may be noted in eqs 3A and 3B for Mn and eqs 8A and SB for K2O, where the ratio was less than one in both of the smaller groups, and for Zr, Cr and Ti in one

or the other of the smaller groups. The use of the

air content of the 1:4 mortar as an independent

variable, as in eq 5, resulted in a slightV lower

S.D. value than in eq 4. When this variable was

used, the coefficient, and the coef./s.d. ratios of Na20, K2O, and Loss were also affected. The contributions of the variables to the 28-

day to 10-year compressive-strength-gain values were calculated from eq 3 of table 7-62 and are presented in table 7-64 together with the cal- culated ranges of these contributions. Increases

in C2S, loss, and Ti with possibly Zr, Cr, Co, and

Mn were associated vnth the higher compressivestrength-gain values, and increases in C3A, Na20,

and fineness, plus possibly K2O, were associated

with lower compressive-strength-gain values. Although C2S and C3A have a dominant role, other

variables may also have an effect on the compressive-strength gain between 28 days and 10 years.

5.18. Compressive-Strength-Gain Ratio From

28 Days to 10 Years (STXY-ST28)/ST28

The frequency distributions of the 28-day to 10-year compressive-strength-gain-ratio values for the different types of cement are presented in

table 7-65. There is overlapping of the values for

the different types of cement, and in each of the

types, as classified, there was a rather broad range

of values.

Equations relating the compressive-strengthgain values to various independent variables are presented in table 7-66 for AE+NAE cements,

and in table 7-67 for the NAE cements alone. In

the series of equations 1, 2, 3, or 5, 6, 7, where

additional variables were included, there was in every instance a significant reduction in the S.D.

value obtained. Pb had a coef./s.d. ratio greater

than 1 in eqs 3 and 4 where the major compounds

were used, but not when used with the variables

in eqs 7 and 8, where the major oxides were used.

The equations for the "odds" and "evens" in the

array of cements, (eqs 3A, 3B, 7A, and 7B)

indicated that K2O and all of the trace elements

had coef./s.d. ratios less than 1 with one or the

other or both of the smaller lots of cement. The

only one of these variables that turned out to be

consistently significant was Cr. The observations relative to the results pre- sented in table 7-66 for the AE+NAE cements

in general are also applicable to table 7-67 for the NAE cements.

The contributions of the variables to the

compressive-strength-gain-ratio values were cal- culated from eq 3 of table 7-66 and are presented

in table 7-68 together \vith the calculated ranges

of these contributions. Increases in C3A, Na20,

and fineness and possibly Cu were associated

42
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44
Table 7-60. Calculated contribution of independent variables

to compressive-strength-garn ratio {1-year — 28-day) 128-day,

SGR{3), of 1:2.76 {cement to graded Ottawa sand) mortar

cubes, water-stored, and the calculated ranges of such

contributions

Independent variable'

Range of variable

(percent)

Coeiucients from eq 3 of

J- ^ V^l n ff CO taDle 7-00

Oalculatecl contribution

10 b Lr XS.\6)

Oalculaieu range of contribution to

L/OnSt. — T"!' *^oo CaA 1 to 15 —0. 0325 ft ftQO n jlQfi 0 456 C3S -. 20 to 65 -0. 0118 -0.236 to -0.767 o]531 C4AF 1 to 16 -0. 0115 -0. 012 to -0. 184 0. 172 Na20 0 to 0.

7

-0. 1433 0 to -0.100 0. 100 K2O 0 to 1.

1

-0. 1434 0 to -0.158 0.158 APF *2500 to 5500 -0. 000076 -0. 197 to -0. 418 0. 221

Air, 1:4 1 to 21 +0. 0029 +0. 003 to +0. 061 0.058 mortar**

Loss 0. 3 to 3. 3 +0. 0787 +0. 024 to +0. 260 0.236 P" 0 to 0.

5

+0. 1304 0 to +0.065 0.065 Co** 0 to 0. 01 +8. 504 0 to +0.085 0.085

'cm •i/g. '•Doubtful significance. Coef./s.d. ratio less than 2.

with decreases in the compressive-strength ratio,

and increases in the other variables which were

significant with increases in the compressivestrength ratio. K2O, Zr, Co, Ti, Mn, Pb were

not highly significant.

5.19. Compressive-strength Ratio of 1-Year

(Water- Stored/Moist-Air-S t o r e d ) Specimens

The frequency distributions of the 1- year (water-stored/moist-air-stored) compressive-strength values for the different types of cement are presented in table 7-69. The median

value for this group of cements was slightly less than 1. Of the 199 cements, 154 had lower compressive strength when stored in water than when

stored in moist air. There was no great distinction

between the different types of cement, either

with respect to the range of values, or the actual

values.

The results of plots of the 1-year compressivestrength ratio, (water-stored/moist-air-stored), versus various independent variables are presented

in figure 7-5 together with plots of some other

strength ratios. In plots for the strength-ratio versus the independent variables, Si02, AI2O3,

CaO, MgO, SO3, C3A, C3S, C2S, A/F, S/(A+F),

and APF, the absolute value of the quadrant

sum was greater than 11, a value previously

used to indicate that there is a relationship at the five percent probability level. Equations relating the 1-year compressive

strength ratio (water-stored/moist air-stored) to combinations of independent variables are pre- sented in table 7-70 for the AE+NAE cements

and in table 7-71 for the NAE cements. The re- ductions in the S.D. values resulting from the

added independent variables were significant when

comparing eqs 1 and 2, or 3 and 4 (see table 7-75).

Most of the independent variables, other than the

constant, the C3S and Zr, had relatively low

coef./s.d. ratios when the larger group of cements

were used in the calculations, and P and Li were

of doubtful significance both with compounds or

oxides. When equations for the smaller groups,

the "odds" and "evens," were calculated, the

coef./s.d. ratios were often less than 1 in one or the other of these lots of cement.

No separate table was prepared indicating the

calculated contributions of the different variables.

However, it appears from tables 7-70 and 7-71

that increases in C3A, and C3S with possibly

C4AF, SO3, Na20 and P are associated with decreases in the strength ratios, and increases in

MgO, Zr, V, and Rb, and plus possibly Li are associated with increases in the strength ratios.

Table 7-61. Frequency distribution of cements with respect to compressive strength

change from 28 days to 10 years of 1:2.75 {cement to graded Ottawa sand) mortar cubes, water-stored

Compressive strength change, psiXlO- Type -2.0 -1.5 -1.0 -0.5 0 +0.5 +1.0 +1.5 +2.0 +2.5 +3.0 +3.5 +4.0 Cement to to to to to to to to to to to to to Total -1.5 -1.0 -0.5 0 +0.5 +1.0 +1.5 +2.0 +2.5 +3.0 +3.5 +4.0 +4.6 Number of cements

I _ 6 11 16 25 8 10 2 78 lA 1 2 4 1 8 n 2 3 9 8 20 5 5 4 56 IIA 2 2

Ill 3 3 1 0 1 2 16 niA.-. 1 1 2 rv& V. 3 1 1 1 1 7

Total. 4 9 15 27 40 20 34 8 6 4 1 1 168

276-694 0-68—

4

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47
Table 7-64. Calculated contribution of independent variables

to compressive strength gain from 28 daijs to 10 years, SGH), of 1:2.75 {cement to graded Ottawa sand) mortar

cubes, water-stored, and the calculated ranges of such

contributions, psi

Independent

variable

Range of variable

(percent)

Coefilcients from eq 3 of table 7-62

Calculated

contribution to SG(4)

Calculated range of contri- bution

to SG(4)

Const. =+1354 CsA 1 to 15 -122.3 -122 to -1834 1712 CzS 5 to 50 +54. 87 +274 to +2740 2466 NajO- - 0 to 0.

— 1255 0 to —878 fi7fi 0 to 1.

-482.oto -531 531 APF 2500 to 5500 -0. 4539 -1135 to -2496 1361 Loss - 0. 3 to 3. 3 +370.

+111 to +1224 1113 Zr** 0 to 0.

+1938 Oto +969 969 Cr** 0 to 0. 02 +19682 oto +394 394 Co" 0 to 0. 01 +56347 oto +563 563 Mn** 0 to 1.

+466. 2 Oto +466 466 Ti 0 to 1.

+1067 0 to +1067 1067

•cm 2/g. **Doubtful significance. Coef./s.d. ratio less than 2.

Table 7-65. Frequency distribution of cements with respect

to strength-gain ratio from 28 days to 10 years of 1:2.76 {cement to graded Ottavia sand) mortar cubes stored in water

[SGR(4) = (STXY-ST28)/ST28]

Strength-gain ratio

_

-0. 45 -0.30 -0. 15 0 0.15 0.30 0.45 0.60 0.75 0.90 1.05 1.20 lype to to to to to to to to to to to to Total cement -0.30 -0. 15 0 0.15 0.30 0.45 0.60 0.75 0.90 1.05 1.20 1.35

Number of cements

I 2 11 20

3

4

32

3

14

10

2

192

2

4 798

55

2

16

2

7

lA

II 1 10 5 2 IIA

III 1 6

1 6 1 IIIA 1 TV &V 3 1 1 1 1

Total.- 3 19 33 51 38 15 5 3 1 1 169

Table 7-66. Equations relating the compressive-strength-gain ratio, {10-year

Equation Note Const. C3A C2S CaO SiOj FejOs NajO

(')

(')

(')

(2)

(2)

(')

(')

(')

(')

(2)

SGR(4)

s.d. SGR(4)

s.d. SGR(4)

s.d. SGR(4) (odd) = s.d. SGE(4)(even) = s.d. SGR(4)

s.d. SGR(4)

s.d. SGR(4)

s.d. SGR(4)

s.d. SGR(4) (odd) =

s.d. SGR(4)(even) = s.d. SGR(4)

s.d.

= +0.3154

= (0.1384)

= +0.4049

= (0.1291)

= +0.1784

= (0.1380)

= +0.0210

= (0.1784)

= +0.3311

= (0.2213)

= +0.2586

= (0.1531)

= -0.6120

= (0.6746)

= -0. 1090

= (0.7880)

= -0. 1855

= (0.8324)

= +0. 8874

= (1.2979) -0.5612

(1. 2145) -0. 1269

(0. 8299)

-0. 0292

(0. 0043) -0. 0248

(0. 0041) -0.0247

(0. 0041) -0. 0239

(0. 0054) -0. 0265

(0. 0064) -0.0205

(0. 0042)

' 152 cements; Avg=0. S.D. =0.1915. 2 76 cements.

+0. 0089

(0. 0021)

+0. 0108

(0. 0019)

+0. 0120

(0. 0019)

+0. 0135

(0. 0024) +0. 0100

(0. 0034) +0. 0121

(0. 0018) -0.0248

(0. 0105) -0. 0297

(0. 0109) -0. 0335

(0. 0116) -0. 0505

(0. 0178) -0. 0256

(0. 0173) -0.0349

(0. 0115)

•Coef./s.d. ratio less than 1.

+0. 1021

(0. 0116) +0. 1028

(0. 0116)

+0. 1094

(0. 0113) +0. 1065

(0. 0159) +0. 1059

(0. 0186) +0. 1129

(0. 0110)

+0. 0583

(0. 0167) +0. 0531

(0. 0159)

+0. 0511

(0. 0158) +0. 0523

(0. 0211)

+0. 0508

(0. 0254) +0. 0528

(0. 0158)

-0. 2651

(0. 0667) -0. 1118

(0. 0508) -0. 2542

(0.0645) -0. 0925

(0. 0515) —0. 1876

(0. 0807) -0. 0728

(0. 0656) -0.3224

(0. 1246) •-0. 0682

(0. 0943) -0. 2576

(0. 0642) -0. 1071

(0. 0521)

-0. 2630

(0. 0655) -0. 0872

(0. 0591) -0. 2523

(0. 0651) -0. 0668

(0. 0605) -0. 1916

(0. 0820) -0. 0913

(0. 0877) -0.3191

(0. 1245) *- 0.0440

(0. 1002) -0. 2585

(0. 0650) -0.0812

(0. 612)

48
Figure 7-5. Results of plotting ratios oj compressive strength determined at different ages of 1:2.75 {cement to graded Ottawa

sand) mortars on the "Y" axis versus various independent variables on the "X" axis.

'Note (1) Ratio of number of plotted points in pairs of diametrically opposite quadrants. Note (2) General trend of line drawn through plotted points. Note (3) Apparent nature of relationship. L-linear; NL-nonlinear; NO-no apparent relationship; and L=-nature of relationship not determinable. Note (4) Quadrant sum in corner test. (See reference [8].) **Stored in moist air for 24 hours, then water for 6 days then in laboratory air at 23° C, 50 percent RH for 49 weeks, then water for 2 weeks. — 28-day) 128-day, water-stored, for AE-\~ NAE cevients to various independent variables APF WAGN. Loss Zr Co Cr Ti Mn Pb Cu S.D.

-0. 000053

(0. 000026)

-0. 000096

(0. 000026)

-0. 000066

(0. 000026)

-0. 000039

(0. 000034)

-0. 000097

(0. 000042)

0. 1441

+0. 0711

(0. 0223)

+0. 0713

(0. 0221) +0. 0595

(0. 0305)

+0. 0967

(0. 0364)

+0. 0492

(0. 0205)

0. 1320

+0. 3805

(0. 2548) +3.9123

(1.8724) *+0. 3102

(0. 3239)

+0. 4614

(0.2506)

+12. 28

(8. 61)

+15. 31

(9.20) *+24.65

(26. 88)

+11. 30

(8. 60)

+5. 494

(2. 650) *+3. 335

(3. 542)

+4. 708

(4. 603) +5. 949

(2. 615)

+0. 1989

(0. 1087) *+0. 1505

(0. 1559) *+0. 0563

(0. 2111)

+0. 1952

(0. 1082)

+0. 0964

(0. 0833) *+0. 0024

(0. 1022)

+0. 2211

(0. 1402) +0. 0793

(0. 0829)

+2. 235

(2. 066) +2. 875

(2. 159)

* -0.430

(5. 507) +2. 339

(2. 056)

-2.829

(1.636)

-3. 170

(1.754) +0. 042

(3. 923)

-3. 170

(1. 633)

0. 1253

0. 1135

0. 1381

-0. 000142

(0. 000060)

0. 1248

+0. 000029

(0. 000024) -0. 000083

(0. 000025) -0. 000058

(0. 000025)

-0. 000033

(0. 000033) -0. 000074

(0. 000039)

0. 1446

+0. 0773

(0. 0234)

+0. 0750

(0. 0233)

+0. 0549

(0. 0322)

+0. 1029

(0. 0386) +0. 0571

(0. 0215)

0. 1320

+0. 3645

(0. 2568) +4. 1126

(1.8852)

•+0. 2823

(0. 3250)

+0. 4320

(0. 2529)

+14. 14

(8. 63) +13.38

(9.25)

*+23. 76

(23.80)

+13. 57

(8.61)

+5. 281

(2. 711)

+4. 515

(3. 799) •+3. 991

(4. 670)

+5. 706

(2. 680)

+0. 1976

(0. 1091)

*+0. 1387

(0. 1566) •+0. 0386

(0. 2096)

+0. 1944

(0. 1087)

+0. 1193

(0. 0898)

-0. 0084

(0. 1159) +0. 2393

(0. 1469)

+0. 1030

(0. 0896)

-2. 627

(1. 664) -3. 418

(1.890) *-0. 464

(4. 004) -2.884

(1. 662)

0. 1255

0. 1142

0. 1381

-0. 000117

(0. 000047)

0. 1250

49
Table 7-67. Equations relating the compressive-strength-gain ratio , (10-year

Note

(')

(')

(')

(2)

(')

(')

(')

(')

(-)

(2)

(')

Const.

SGR(4)

s.d. SGR(4)

s.d. SGR(4)

s.d. SGE{4)(odd) =

s.d. SGR(4)(even) = s.d. SGR(4)

s.d. SGR(4)

s.d. SGR(4)

s.d. SGR(4)

s.d. SGR(4)(odd) = - s.d. SGR(4){even) = s.d. SGR(4)

s.d.

= 4-0.3300

= (0.1475)

= +0.4100

= (0.1369)

= +0. 1820

= (0.1440)

= +0. 1459

= (0.2106) +0. 2808

(0. 2230)

= +0. 2557

= (0.1619)

= -0. 6160

= (0.7325)

= +0. 0343

= (0.8455)

= -0. 0608

= (0.8879)

-0.4588

(1. 3948) +0.5683

= (1.3145)

= -0. 0194

= (0.8867)

CsA

—0.0288 +0. 0085

(0. 0046) (0. 0022) —0. 0237 +0. 0107

(0.0044) (0. 0020) —0. 0239 +0.0118

(0. 0043) (0. 0020) -0. 0211 +0. 0122

(0. 0065) (0. 0026) -0. 0272 +0. 0108

(0. 0066) (0. 0034) -0.0259 +0. 0120

(0. 0045) (0. 0020)

CaO

-0. 0235

(0. 0113) -0. 0302

(0. 0116) -0. 0339

(0. 0123) -0. 0279

(0. 0186) -0.0425

(0. 0187) -0.0354

(0. 0122)

Si02

+0. 0982

(0. 0125) +0.0988

(0. 0124) +0. 1052

(0. 0120) +0. 1068

(0.0181) +0. 1031

(0. 0182)

+0. 1096

(0. 0117)

FeaOs

+0. 0615

(0. 0180) +0. 0534

(0. 0172)

+0. 0517

(0. 0169) +0. 0459

(0. 0260) +0. 0557

(0. 0261)

+0. 0534

(0. 0169)

Na20

-0. 2716

(0. 0693) -0.1254

(0. 0542) —0. 2552

(0. 0682) —0. 0961

(0. 0556) -0.2388

(0. 0912) -0. 1476

(0. 0794) -0. 3750

(0. 1328) *-0.0436(0. 0936) -0. 2597

(0. 0681) -0. 1077

(0. 0561)

-0. 2697

(0. 0692) -0. 1058

(0.0630) -0. 2553

(0. 0688) -0. 0759

(0. 0652) -0. 2293

(0. 0942) *-0.0834(0. 1046) -0.3854

(0. 1311) •-0.0538(0. 0989) -0. 2624

(0. 0689) -0. 0874(0.0659)

1 140 cements; Avg=0.08582; S.D. =0.1942. 2 70 cements. *Coef./s.d. ratio less than 1.

5.20. Compressive-Strength Ratio of 1-Year

(Air-Stored) to 28-Day, Water-Stored

Specimens

The frequency distributions of the ratios of the compressive strength values of the 1-year

air-stored (7-day water-cured, then 49 weeks in laboratory air, then 2 weeks in water, and tested

vv^et) to the compressive strength values of speci- mens stored in water until tested at 28 days are presented in table 7-72 for the different types of

cement. Although the average compressive

strength after the two types of storage are nearly

equal, 5237 psi for STlA, and 5037 psi for ST28

for the AE-)-NAE cements, there was a considerable spread of the ratios of the different cements.

Of the 199 cements, 57 had lower compressive

strength values for the 1-year air-stored specimens

than for those cured 28 days in water.

Equations relating the compressive strength

ratios for specimens tested after the two conditions

of storage, to various independent variables are presented in table 7-73 for the AE+NAE ce- ments, and in table 7-74 for the NAE cements.

The independent variables used in eq 1, table

7-73 resulted in a significant reduction in the S.D.

value. With the added variables in eqs 2 and 3, further significant reductions in the S.D. values were attained. A further significant reduction was

not attained in eq 5 with the added variables

(See also table 7-75.) The MgO had a coef./s.d.

ratio less than one \vith the variables in eq 5 and 6

where the major oxides were used in the equations.

The coef./s.d. ratio was less than one in one or both of the "odds" or "evens" groups for C4AF,

FezOa, SO3, Mn, and Cr. The coefficients for Pb

were negative in eqs 3B and 6B but they were

positive in eqs 3, 3A, 6, and 6A. In table 7-74 the

50
~ 28-day) 128-day, waler-stored, for NAE cements to various independent variables

APF WAGN. Loss Zr Co Cr Ti Mn Pb Cu S.D.

-0. 000055

(0. 000028)

-0. 000099

(0. 000028)

-0. 000C69

(0.000027)

-0. 000056

(0. 000039)

-0. 000086

(0. 000042)

0.1487

+0. 0726

(0.0236)

+0. 0713

(0. 0234)

+0. 0554

(0. 0312)

+0.0832

(0. 0396)

+0. 0476

(0. 0220)

0.1369

+0. 3931

(0. 2636)

•+0. 3080

(0. 6810)

+0. 4543

(0. 3309) +0. 481.3

(0. 2598)

+16.84

(9. 31)

+16. 79

(11.36)

+25. 54

(23. 38) +14.43

(9. 35)

+5. 418

(2.807) +8. 841

(4. 261) •+1. 024

(4. 580) +5. 977

(2. 777)

+0.2009

(0. 1173) •+0. 1015

(0. 1623)

+0. 3225

(0. 2072)

+0. 1987

(0. 1171)

+0. 1137

(0. 0899) •+0. 1097

(0. 1117) +0. 1101

(0. 1823) +0. 0975

(0. 0895)

+2.229

(2. 128) +2. 730

(2. 388) •-1.888

(8. 155) +2.311

(2. 122)

-2.634

(1.696)

-5. 204

(3. 720) •-0.892

(2. 225) -2. 962

(1. 695)

0.1286

0.1280

0. 1373

-0. 000143

(0. 000054) 0.1282

-0. 000031

(0. 000027)

-0. 000087

(0. 000027)

-0. 000059

(0. 000027) -0. 000055

(0.000039)

-0. 000069

(0. 000042)

0. 1405

+0. 0775

(0. 0246)

+0. 0735

(0.0245)

+0. 0626

(0. 0342)

+0. 0847

(0. 0405)

+0. 0541

(0. 0229)

0.1360

+0. 3842

(0. 2658) +0. 3180

(0. 6905)

+0. 4636

(0. 3317)

+0. 4584

(0. 2624)

+17.28

(9. 31)

+15. 62

(11. 18)

+22. 21

(18. 83) +16.40

(9.32)

+5. 284

(2. 867) +8.937

(4.361) *+1.291

(4. 490) +5. 775

(2. 841)

+0. 2009

(0. 1181)

•+0. 0902

(0. 1641)

+0. 3019

(0. 2052) +0. 1984

(0. 1179)

+0. 1302

(0. 0965)

+0. 1730

(0. 1310) •+0. 0777

(0. 1875) +0. 1146

(0. 0964)

-2.488

(1. 723) -5. 091

(3. 760) •-0. 928

(2. 232) -2. 741

(1.722)

0. 1290

0. 1293

0. 1368

-0. 000120

(0. 000051)

0. 1287

T.\BLE 7-68. Calculated contributions of independent vari- ables to compressive-strength-gain ratio, {10-year —28-

day) 1 28-day, SGR{4), of 1:2.75 {cement to graded Ottawa

sand) mortar cubes, water-stored, and the calculated ranges of such contributions

Independent

variable Range of variable

(percent)

Coefficients from eq 3 of table 7-66 Calculated contribution to SGR(4)

Calculat- ed range

of contribution

to SGR(4)

CjA

Const.=+0.1784

1 to 15 -0. 0247 -0. 0247 to -0. 3705 0.3458 CaS 5 to 50 +0. 0120 +0. 0600 to +0. 6000 0. 5400 NajO..._ 0 to 0.

7

-0. 2542 0 to -0.1779 0. 1779 KiO".__ 0 to 1.

1

-0. 0925 0 to -0.1018 0. 1018 APF._.. •2500 to 5500 -0. 000066 -0. 1650 to -0. 3630 0. 1980 Loss 0. 3 to 3.

3

+0. 0713 +0. 0214 to +0. 2353 0. 2139 Zr'* 0 to 0.

5

+0. 3805 0 to +0. 1902 0. 1902 Co«» 0 to 0. 01 +12.28 0 to +0. 1228 0. 1228 Cr 0 to 0.02 +5. 494 0 to +0. 1099 0. 1099 Xi»» 0 to 1.0 +0. 1989 0 to +0. 1989 0. 1989 Mn*»..._ 0 to 1.0 +0. 0964 0 to +0. 0964 0. 0964 Pb".. 0 to 0. 05 +2. 235 0 to +0. 1118 0. 1118 Cu".... 0 to 0. 05 -2.829 0 to -0.1415 0. 1415

•cmVg.

••Doubtful significance. Coef./s.d. ratio less than 2.

T.\BLE 7-69. Frequency distribution of cements with respect

to compressive-strength ratio, STIY/STIM, of 1:2.75

{cement to graded Ottawa sand) mortar cubes

Compressive strength ratio

0.80 0.85 0.90 0. 95 1.00 1. 05 1. 10 1. 15 Type cement to to to to to to to to Total

0.85 0. 90 0.95 1.00 1.05 1. 10 1. 15 1.20

Number of cements

I 6 19 26 18 7 3 1 1 81 lA 3 1 2 2 8

II 12 17 22 15 68 "1

IIA 1 1 1 3

III 3 4 9 'T 20 IIIA 1 .... 3 IV &V i" "5'

2 "2 4 15

Total 10 40 59 45 29 10 3 2 198

51
sS+

<5sBSdI n

N i-H

CM

O

Tin (N

CO 1-1 t>- 00

lO o

CO M< TP CO d d

O o o oI ^ O CO o oo

M .-I

d (N

lOCO

03

3152

4447) 4742 3666) «D

dd

dd

i-H O"

0820 o 0650) OO

35

oo

oo oo od

00

00 CD O O CO '-'

00 CO (N

05 0 CO CO

CO I-H oo d d d d

oS 05 05

O en o o

CO

lO o o

00 CO

_ - tM .-HO 00 d d d d

00 ^ o o do

00 ^ O Oi

i-ii^ 00 O ^ O CO 00 ^ o do d d

M CD

CO Oi O CO

I-H »0

00 So+ o o o o o o o o d

dd

d

oO

oSI o o dd

05 o o Clo

10 r-* ^ 00 0> 10

CO ^ 00 00 O OI ^ O O

t~ o 00

ddI 00 00 d d d d o o dd

£3S o o dd

CO -rtf 10lij COijpj 00 O CD CD (D

<M

OO

O 00 00 d d do +- +-

to 0> b- CO 00 CO

t— CO

O CO CO ^ o 1-t o 00 00 00 00 o o d d d d f I o oI ^

;9; CO

£3 CO 1>. 52 CDCO Soo 00 o dd d d 1 ^ I ^

00

ddI ^ oO

Oo o o od o oI ^

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00 00

OCT)

O i-i eg o

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II II

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II II II II

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1-H

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wd 00

CO CO N d

II II II II

P5'd (li'd CcjTj tfT3 Pi'o p^-d tf-d tf'd

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--I CD S" CO

N OS OS (N ED to ^ O CO »0 rf< "3 wica. t^co c4c6 +s +w d d do

OS 00 O o 00I o o 00

05532 0 d 1 d

CO

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CO l-H OS 00

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to iM

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tot; tOrJl oo!*

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00

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CO

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!i o o o 00

dd $0

CDO

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CO CO o o o oI doI ^ o o d dI ^ o 10

CO 10

CM I-H O O d d

HO J!? 00 O O d dI O o o o d d

iM 00 o o d d

(M

00 CO 00 o d d

Oo

00 o

rH

O o o o o o oI ^

CO

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0> OS

ur> CO <M o o 00

Ttt I-H --H CO

r-- CD o (M CO CO CO 00 00

00 00

eg o o o 00

O I-H C5 1-H o o 00 00

CO CD -"S^ .-H 00 !> Oi CO 00 00o o 00 00

eg OS

00 10

»-H

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OS CO CO

»H go OS 00 fH O ^O rHC

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1-H i-H OS

00M CO ^d rHO dd

II II

Pi'd pH-d tf-d P^-d Phts On'd tf'd p^^d

CQui mwi Oiw Toco cQw COw CQm cCm

52
coef./s.d. ratio for Pb was less than one in the

"evens" groups (eqs 3B and 6B). Comparing eqs

4 and 5 of table 7-74 it may be noted that the use

of the added variables in eq 5 resulted in a re- duction of the S.D. value significant only at the

5 percent probability level (see also table 7-75).

Cr and SO3 were not highly significant.

Tables 7-73 and 7-74 indicate that increases in C3A, C3S, C4AF, and Ba are associated with lower

compressive strength ratios and that increases in MgO, Loss, air content, CO, Pb, Mn, and V, and

possibly SO3 are associated with higher compressive strength ratios of the 1-year air-stored to 28-day water-stored specimens.

Table 7-72. Frequency distribution of cements with respect

to compressive strength ratios of 1-year air-stored to 28-day

water-stored 1:2.75 {cement to graded Ottawa sand) mortar cubes

Compressive strength ratio

0.7 0.8 0.9 1.0 1.

1

1.2 1.3 1.4 1.5 1.6 Type cement to to to to to to to to to to Total

0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Number of cements

I 1 7 16 42 14 1 1 82 lA 4 2 2 8

ii.'.y.V-'.'.'.v. "i" 20' 25" 14 4 2 i' i" 68 HA _ 1 1 1 3 m "2" "% 9 1 20 niA 3 3 iv& v..

"2

6 4 1 2 15 Total 1 12 44 86 38 8 7 2 1 199

6. Discussion

6.1. Compressive Strength of Different Types

of Cement

By plotting the average compressive strength

values of the different types of nonair-en training

cements versus the age of test on a semilog scale, as presented in figure 7-1, it was noted that the

averages of the different types were different. The almost linear character of the relationship

(on the log scale) at the early ages changed at

different ages with the different types of cement, and

as a result, some of the lines in the graph crossed.

The various tables presented to show the fre- quency distribution of the compressive strength

values at the different test ages indicated that

there was a considerable overlapping of the values

for the cements as classified into the different

types. This was found, not only for the strength

values at a given age, but for the gain in strength

between the various ages, or the percentage

strength increase after some earlier test. The use

of average values for predicting compressive

strength or compressive strength gain for a cement

of a given type may, therefore be inadequate and

result in erroneous predicted values. The fact

that there was such an overlapping and range of values for the cements of the different types as

classified indicate that it is not sufficient, especially in research reports, to merely describe a cement as meeting the requirements of a certain

type.

It was also noted in figure 7-1 that there was a

retrogression of the average compressive strength

values for each of the types of cement after 1-year

water storage, which was, of course, not true for

all of the cements mthin each group. Of the 189

cements for which values were obtained, 68 had

higher compressive strength at 5 years than at 1 year, and, of 169 cements, 23 had higher compressive strength at 10 years than at 1 year, and 26

had higher strength at 10 years than at 5 years.

It was also noted that 154 of the 199 cements had

lower compressive strength when stored in water

for 1 year than when stored in moist air for the same period.

The retrogression of compressive strength of

small, relatively porous, water-stored specimens

may be attributed to leaching, to some destructive action which causes strains within the specimens, or to possible other causes. If specimens

made from all cements had shown this

tendency of lower strength at 5 and 10 years, the

effect could definitely be attributed to leaching.

Mortars made of some cements may have this tendency to a greater extent than others.

The equations presented relating the compressive-strength values to combinations of variables

indicated that an increase in the C3A content was

associated with lower compressive strength values

at 1, 5 and 10 years, but was associated with

higher compressive strength values at the earlier ages. The C3A content may then be one of the

contributing factors (others are indicated in the

tables) that confirm previously published reports.

It was noted at one of the five laboratories that

made these tests that the 5- and 10-year speci- mens were coated with a hard crust. (This condition was not found in the other 4 laboratories.)

It was necessary to remove this coating Avith* abrasive cloth, as required by specifications, a procedure which may by itself have resulted in

lower compressive strengths.

6.2. Relationships of Compressive Strengths

Determined at Different Ages

The relationships of the compressive strengths

at various ages to those at earlier ages are pre- sented in table 7-76. The equations were calculated Avith the dependent variable (the compressive strength at one age) as a function of a constant

plus the compressive strength at an earher age. The s.d., and the S.D. values are presented to- gether Avith the reduction in variance, "F," re- sulting from the determination of the constant

and coefficient of one independent variable. With

•; h.e number of degrees of freedom in these equations, a value of 4.72 or above is significant at the one percent probability level, and a value of 3.05

or above, significant at the five percent level. The

53
Table 7-73. Equations relating the compressive strength ratio, {1-year air-stored/

Note

(')

(')

(')

(2)

(2)

(1)

(')

(')

(2)

(2)

SR(2)

s.d. SR(2)

s.d. SR(2)

s.d. SR(2)(odd) ^ s.d. SR(2)(even) ^ s.d. SR(2)

s.d. SR(2)

s.d. SR(2)

S.d. SR(2)(odd)

s.d. SR(2)(even)

s.d.

Const.

= +1.336

= (0.080)

= +1.263

= (0.081)

= +1. 187

= (0.081) =+1.243

= (0.092)

= +1. 179

= (0.149)

= +2. 747

= (0.398)

= +2.340

= (0.432)

= +2.370

= (0.430)

= +2.759

= (0.587)

= +1. 903

= (0.661)

C3A

-0. 00841

(0. 00253)

-0. 01073

(0. 00261)

-0. 00916

(0. 00262)

-0. 00901

(0. 00345)

-0. 00824

(0. 00395)

CsS

-0. 00442

(0. 00102)

-0. 00468

(0. 00103)

-0. 00436

(0. 00098)

-0. 00501

(0. 00108)

-0. 00380

(0. 00191)

C<AF

-0. 0092

(0. 0036) -0. 0096

(0. 0036) -0. 0102

(0. 0034)

-0. 0162

(0. 0039) •-0. 0032

(0. 0060)

CaO

-0. 0348

(0. 0062) -0. 0321

(0. 0062)

-0. 0316

(0. 0061)

-0. 0367

(0. 0078)

-0. 0241

(0. 0097)

SiOi

+0. 0230

(0. 0052)

+0. 0296

(0. 0060)

+0. 0256

(0. 0061)

+0. 0252

(0. 0074)

+0. 0243

(0. 0102)

FejOs

-0. 0189

(0. 0095) -0. 0149

(0. 0095) -0. 0210

(0. 0091) -0.0424

(0. 0115) +0. 0029

(0. 0148)

178 cements; Avg = 1.049; S.D. =0.1032. I cements. *Coef./s.d. ratio less than 1.

Table 7-74. Equations relating the compressive strength ratio, {1-year air-stored/

Note Const. CsA CjS CiAF CaO Si02 FesOs

(')

(')

(')

(•)

(2)

(')

(')

(I)

(2)

(2)

SR(2)

s.d. SR(2)

s.d. SR(2)

s.d. SR(2)(odd) = s.d. SR(2) (even) = s.d. SR(2)

s.d. SR(2)

s.d. SR(2)

s.d. SR(2) (odd) = s.d. SR(2) (even) = s.d.

=+L324

= (0.086)

= +1.258

= (0.086)

= +1. 188

= (0.085)

= +1. 274

= (0.099)

-- +1. 065

= (0.156)

= +2.627

= (0.415)

= +2.187

= (0.449)

= +2.246

= (0.452)

= +2.161

= (0.521)

= +2.396

= (0.845)

-0. 00926

(0. 00261)

-0. 01148

(0. 00267)

-0. 00971

(0. 00270) -0. 00863

(0. 00342)

-0. 00902

(0. 00435)

-0. 00422

(0. 00106) -0. 00446

(0. 00107] -0. 00416

(0. 00102)

-0. 00517

(0. 00111)

-0. 00278

(0. 00197)

-0. 0100

(0. 0037) -0. 0105

(0. 0036) -0. 0107

(0. 0035) -0. 0115

(0. 0043) -0.0073

(0. 0060) -0 0333

(0. 0064) -0. 0303

(0. 0064)

-0. 0299

(0. 0063) -0. 0291

(0. 0070) -0.0311

(0. 0120)

+0.0238

(0. 0054)

+0. 0306

(0. 0061)

+0. 0262

(0. 0063)

+0. 0286

(0. 0072) +0. 0219

(0. 0108)

-0. 0194

(0. 0098) -0. 0151

(0. 0098) -0. 0206

(0. 0094) -0. 0217

(0. 0120) -0. 0172

(0. 0156)

'166eements: Avg = 1.040; S.D. =0.0977. ^83 cements. 'Coef./s.d. ratio less than 1. 54
28-day water-stored) for AE-\-NAE cements to various independent variables

S03 Loss Air 1:4 mortar Ba Co Pb Mn V Cr 8.D.

+0. 0112

(0. 0018) +0.0094

(0. 0018)

+0. 0096

(0. 0017) +0. 0113

(0. 0021) +0. 0072

(0. 0027) +0. 0095

(0. 0018)

+0. 0092

(0. 0018) +0. 0095

(0. 0017) +0. 0112

(U. UOJl;

+0. 0070

(0. 0027)

0. 08797

+0. 0316

(0. 0211) +0. 0326

(0.0202) •+0.0281

(0. 0283)

*+0. 0175

(0.0293)

+0. 0277

(0. 0127) +0. 0366

(0. 0123) +0. 0439

(0. 0159)

+0. 0320

(0.0191)

0.08490

-0. 4265

(0. 2065) -0.3884

(0. 2373) —0. 6465

(0. 3630

+10.04

(4.43)

+13. 85

( 5.26) + 9.21

( 8.51)

+2. 187

(1.027) +3.210

(1.019) —5. 845

(3. 676)

+0. 0995

(0. 0523) +0. 1238

(0. 0575) *+0.0516

(0. 0969)

+0. 8690

(0. 4149) +0. 8585

(0. 5980) +1.0607

(0. 6147)

+2.412

(1. 617) +2. 297

(2. 114) •+1.247

(2. 440)

0. 07935

0. 06893

0.08625

0. 08551

+0. 0335

(0. 0226) +0. 0322

(0. 0218) *+0. 0265

/n not A \ (0. 0314) •+0. 0215

(0.0312)

+0. 0189

(0. 0127) +0. 0266

(0. 0121) +0. 0284

(0. UlOUJ

+0. 0262

(0. 0190)

0.08465

-0. 4157

(0. 2058)

-0. 3831

(U. Jooo; -0. 6106

(0.3603)

+10. 20

( 4.41) +14.24

( 5. 18) + 9.19

( 8.34)

+2. 226

(1. 022) +3. 373

(1. 002) -5.777

(3. 629)

+0. 1022

(0. 0518) +0. 1342

(0. 0oo9)

*+0. 0449

(0.0960)

+0. 8671

(0. 4133) +0. 8065

(0. 5955) +1.0528

(0. 6073)

+2. 225

(1. 599) •+1.983

(2. 097) •+1.341

(2. 405)

0. 07911

0. 06898

0.08538

28-day water-stored), for NAE cements to various independent variables

S03 Loss Air 1:4 mortal Ba Co Pb Mn V Cr S.D.

+0. 0137

(0. 0039) +0. 0103

(0. 0039)

+0. 0100

(0. 0037) +0. 0054

(0. 0050) +0. 0122

(0. 0060)

+0. 0111

(0. 0039) +0. 0100

(0. 0039) +0.0097

(0. 0037)

• +0.0048

(0. 0050) +0. 0125

(0. 0060)

0. 08817

+0. 0316

(0. 0217) +0.0331

(0. 0209) +0. 0436

(0. 0286) •+0. 0232

(0. 0315)

+0. 0291

(0. 0131) +0. 0373

(0. 0128)

+0. 0437

(0. 0165)

+0. 0364

(0. 0213)

0.08496

-0.4358

(0. 2095) -0. 4784

(0. 2381) •-0.3257

(0. 3855)

+10. 33

( 4.60) +12.24

( 4.85)

+16. 11

(10. 75)

+2.229

(1. 038) +3. 301

(1. 065) *-2.988

(3.451)

+0. 0812

(0. 0548) +0. 1144

(0. 0609) *+0. 0225

(0. 1004)

+0. 8594

(0. 4206) +1. 4902

(0. 6056) *+0. 2991

(0. 6278)

+1.954

(1. 670) *-1.078

(2. 141) +4. 259

(2. 734)

0. 07988

0.06808

0.09101

0. 08613

+0. 0354

(0. 0233) +0. 0342

(0. 0226) +0. 0464

(0. 0306) •+0. 0214

(0. 0343)

+0. 0221

(0. 0130) +0. 0289

(0. 0125) +0. 0364

(0. 0159)

+0. 0281

(0. 0205)

0.08497

-0. 4273

(0. 2096) -0.4833

(0. 2355) *-0. 2783

(0. 3886)

+10.60

( 4.58) +11.85

( 4.71) +15.65

(10. 78)

+2. 316

(1.036) +3. 269

(1.025) *-3. Ill

(3. 458)

+0. 0841

(0. 0544) +0. 1178

(0. 0597) +0. 0157

(0. 1014)

+0. 8601

(0. 4201) +1. 5147

(0. 5977) •-0.2827

(0. 6286)

+1. 735

(1.658) *-1.026

(2. 057) +4. 529

(2. 760)

0. 07987

0. 06734

0.09129

55
Table 7-75. "F" value for significance of reduction of variance due to added variables.

Table Equations "F" ratio D.F.

Critical "F" ratio a=0.01 a=0. 05

7-2 1 2 5.06 3:165 3.90 2. 67

3 4 4. 88 3:165 3. 90 2. 67

5 6 4. 54 3:162 3. 90 2.67

7! 8 5! 69 3:163 3. 90 2.67

1

2

5. 08 3:153 3. 90 2. 68

3 4 4. 95 3:153 3. 91 2. 68

5 6 4. 43 4:150 3. 91 2.68

7,8 5.34 3:151 3.91 2.68

7-6 1 2 4. 61 4:164 3. 42 2. 43

5 6 5. 85 3:166 3. 90 2. 67

7! 8 3. 26 4:162 3. 42 2. 43

9 10 3. 78 4:163 3! 42 2. 43

7-7 1,2 4.67 4:152 3. 43 2. 44

4 5 5. 54 3:154 3.91 2.68

6 7

8', 9

3. 35 4:150 3. 43 2. 44

3'. 52 4:151 3! 43 2.44

8, 10 3. 55 4:151 3. 43 2. 44

1 3 8. 38 5:165 3. 12 2. 27

2', 4 3! 37 1:165 6^78 3! 90

5,6 0. 50 1:165 6. 78 3.90

7-11 1 3 8. 57 5:153 3. 15 2. 28 2,4 4.00 1:153 6^78 3.90

5,6 1.15 1:153 6.78 3. 90

7-14 1 4 6. 45 5: 164 3. 12 2. 27

2! 3 4! 41 3:165 3.90 2. 67

5,6 3. 86 4:165 3.42 2.43

7-15 1 4 7. 13 4:153 3. 43 2. 44

2)3 3] 78 3:153 3] 91 2.' 68 5,6 3.37 4:153 3.43 2.44

7-18 1 4 4. 27 5:167 3. 12 2. 27

2 3 3. 15 5:167 3. 12 2. 27

6!7 3I25 4:166 3^42 2143

7-19 1 4 3. 99 5:155 3. 15 2. 28

2! 3

3'. 01 5:155 3! 15 2.28 5,8 4.06 4:154 3. 43 2.44

6,

7

3. 29 4:154 3. 43 2. 44 7-22 1,2 4. 82 5:162 3. 13 2.28

4,

5

4. 31 6:161 2. 91 2. 15

7-23 1,2 4. 26 6:150 2.92 2.15

4,5 4. 39 6:150 2. 92 2.15

7-26 1 3 7. 81 4 '167 3. 42 2. 43

2! 4 4! 77 3:167 3! 90 2. 67

5,6 5. 00 3:166 3.90 2. 67

7-27 1,3 6.93 4:165 3. 43 2.44

2, 4 4. 41 3:155 3. 91 2.68

5,6 5. 53 3:154 3. 91 2.68 7-30 1, 2 3. 51 5:160 3. 13 2. 28

7-31 1 2 3. 13 5:149 3. 14 2. 27 7-34 •0,1 55. 78 4:151 3. 43 2.44

1,3 11.00 4:147 3. 44 2.44

3 4 4. 50 5:142 3. 14 2. 28 2 5 4. 64 4:143 3. 44 2. 44

q' 7 17. 50 2:148 4. 73 3. 05

7' 8 3. 40 6:142 2. 93 2. 16 7-35 0,1 51. 86 4:139 3.45 2.45

1,2 6. 59 4:135 3. 45 2. 45 2,6 4. 30 4:131 3. 45 2.45

1 3 7. 41 4:135 3. 45 2. 45

3' 4 4. 19 5: 130 3. 15 2. 28

6 7 13. 40 2:136 4. 76 3. 91

7' 8 4. 42 4:132 3. 45 2. 45 7-38 0,

1

15. 07 4:168 3. 42 2. 43

1 2 13. 51 4:164 3. 42 2. 43

2*3 6. 99 5:159 3. 13 2. 27

5' 6 15. 88 4:164 3. 42 2. 43

6 7 7. 72 4:160 3. 42 2. 43 7-39 0,

1

14. 80 4:166 3. 43 2. 44

1 2 7. 64 4:152 3. 43 2. 44

2 3 6. 26 5:147 3. 14 2. 28

5' 6 10 00 4:152 3. 43 2. 44

e' 7

5' 83 6:147 3. 14 2. 28

7-42 0,

1

48. 18 4:165 3. 42 2. 43

1 2 10. 22 3:162 3. 90 2. 67

2)3 7! 99 5:157 3! 13 2! 27 5,6 12. 55 3:161 3. 90 2.67

6,7 8.40 4:157 3.43 2.44

7-43 0,1 43. 47 4:153 3.43 2.44

1,2 8.43 3:150 3. 91 2.68

•Equation 0 refers to the variance for the values themselves with no fitted

56

Table Equations "F" ratio D.F.

Critical a =0.01 a =0. 05

2 3 7. 04 5' 145 2. 28

b 6 10. 58 3* 149 0. yi 2. 68

6* 7 7. 48 4' 145 3. 42 2. 43 7-46 0,1 83. 76 4:174 3.42 2. 43

1 2 19. 29 3' 171 3. 89 2. 66

2* 4 4 59 il. 1 R7 3. 42 2. 43

Q 7 17. 30 3" 170 Q on 0. yu 2. 67

7 8 4. 83 3. 42 2. 43

7-47 0,1 81.50 4:162 3. 42 2. 43

1 2 15 91 0 . ioy 3. 91 2. 68

2* 4 5. 27 4" 155 3. 43 2. 44

6* 7 14. 82 3' 158 Qi 0. yi 2. 68

7'

8

5. 33 4* 154 0. 4o 2. 44 7-50 0,

1

102. 19 4:170 3. 43 2. 43

1 2 12 37 4 * 166 Q AO 2. 43

2' 3 5. 16 5' 161 ^ 1 Q 0. 10 2. 27

5' 6 12. 18 4' 165 3 42 2. 43

6* 7 4. 47 5' 160 0. lo 2. 27 7-51 0,

1

94. 72 4:158 3. 43 2.44

1 2 10 49 4' 154 0. 4o 2. 44

2* 3 5. 49 5' 149 3 14 2. 28

5 6 10 77 * . 100 0. *lo 2. 44

6 7 4 10 0. 14 2. 28 7-54 0,

1

56. 03 5:173 3. 13 2. 27

1 2 14. 68 3" 130 0. oy Z. DO

2 3 4 23 ^ . 1 A7 3. 89 2. 66

4' 6 15 89 3' 170 CQ 0. oy 0 RR Z. OD

6 7 4 81 0. iD( 0. oy 2. 66 7-55 0,

1

51. 31 5:161 3. 13 2.27

1 2 13 03 3* 158 3 90 2. 67

2' 3 3. 88 3* 155 3 90 2 67

4' 6 14. 36 3" 158 3 90 2 67 6 7 4 50 0 . 100 Q on 0. yu 2. 67 7-58 0,

1

45. 40 5:168 3. 13 2.27

1 2 10 75 4' 164 3 42 0 AQ Z. 40

2 3

0- 1 fiO ^. IDJ

A 70 3. 05

5 6 11. 47 4* 164 3 42 2 43

6 7 2 88 2* 162 A 70 0. uo 7-59 0,

1

41. 25 5:166 3.13 2.27

1 2 10 46 4" 152 Q AQ 0 AA Z. 44

2 3 2 23 2" 150 4 73 Q nt; 0. uo

5 6 11 32 4 ' 152 ^ AQ 0. 40 2. 44

7 8 2 24 0 1 i^n Z. lOU A 7Q 4, /O 3. 05 7-62 0,

1

38. 06 4:148 3. 43 2. 44

1 2 12 43 3 * 145 3 91 0 Rfi Z. Do 2 3 4. 06 5 140 0. 10 0 Oil z. zo

5 6 12 81 3" 144 3 91 9 fiR Z. Do

6 7 0. oy 0 . loy 0. 10 0 Ofi

7-63 0,1 33.06 4:136 3. 46 2. 45

1 2 11 64 0 . loo Q QQ 0. VO 0 RQ z. oy 2 3 4 26 • 1 OH 0 . IZO 3 16 0 00 z. zy

6 7

111.1 00y^i ^ . 1 QO 0 . loZ 0. yo 0 RQ z. oy

7 8 4 03 5 * 127 3 16 0 OQ Z. £v 7-66 0,

1

30.11 4:148 3. 43 2.44

1 2 10 46 0 . IrrO "i Qi 0. yi 0 RS Z, 00 2 3 3 27 7* 138 2 77 2 07

5 6 10 80 3* 144 3 91 2 68

6 7 0. 00 0 . loo 0 QQyo 0 ifi Z. ID

7-67 0,1 25. 70 4:136 3. 46 2. 45

1 2 9 94 0. 100 3 98 2 69

2 3 3 22 7 ' 126 2 79 2 09

Of D in QQ iU. 00 1 ^0 0. ioJ 0. yo 0 RQ z. Dy

6,7 3. 46 6:126 2. 95 2.16

7-70 0 1 7 16 7 * 168 2 75 2 07

1 2 4 16 0 . loo 3 13 2 27

u, 0

in on K • 1 7n 0 . 1< u 0. 10 0 07 z. z/ 3,4 3. 55 6:164 2.91 2.15

7-71 0 1

fi 1 n 0. lU 7 • 1 (^7

/ . 10/ 0 7R/O 0 n7 z. u/

If 2 4. 17 5 : 152 Q 1

A

0. 14 0 07 z. z/ n Q U, 0 8. 73 5: 159 3. 14 2. 27

0, ^ 0. 00 D. lOO 0 QO J. yz 0 1 fi Z. ID 7-73 0,1 14.39 6:173 3. 13 2. 27

1 0 5. 25 Q • i7n 0. l/U Q on 0. yu 2 67

0 5. 10 D. 104 0 QI z. yi 2 15

2. 77 2: 171 4. 72 Q OA 0. U4

5, 6 5. 13 6:165 2. 91 0 1

R

z. 10 7-74 0,1 8. 56 6:161 3. 13 2.27

1,2 5. 13 3:158 3. 90 2.67 2,3 4. 46 6:152 2. 92 2.16

0,4 10. 52 5:161 3. 13 2.27 4,5 3. 21 2:159 4. 72 3.06

5,6 4. 49 6:153 2.92 2.16
reduction resulting from the use of the variables was not significant at the one percent level in eq

10, and the five percent level in eq 11. The reduction in variance values were highly significant in

all the other equations.

These equations were calculated on the assumption that the relationship of strength at later ages

to that at earlier ages is linear. This assumption

may not be true in all cases, especially when

cements of different types are combined.

Table 7-76. Relationships of compressive strengths at different ages, to compressive strengths at earlier ages and

comparisons with S.D. values from previous equations

Eq. No Equation S.D.

S.D. from

equations

derived with

chemical and physical

properties

1 ST28

s.d. —T-zyyi = (127)

^-0. 955

(0. 056) ST03 554 147 554 eq 3 table 7-14

2 STIY

s.d. =+5393 = (185) +0.389

(0:081) ST03 QflQ ouy 11 ooo eq o table 7-18

3 STIM

s.d. =+5400 = (190) +0. 565

(0. 083) ST03 828 23 572 eq 2 table 7-22

4 STIA

s.d. =+3668 = (110) +0.737

(0. 048) ST03 479 117 447 eq 3 table 7-26

5 ST5Y

s.d. =+5368 = (216) +0. 335

(0.094) ST03 941 6.3 508 eq 2 table 7-30

6 ST28

s.d. =+2507 = (135) +0. 779

(0. 039) ST07 507 194 554 eq 3

table 7-14

7 STIY

s.d. = +5373 = (218) +0.263

(0.063) ST07 821 8.5 535 eq 3 table 7-18

8 STIM

s.d. = +5200 = (221) +0.435

(0. 065) ST07 830 23 572 eq 2 table 7-22

9 STIA

s.d. =+3388 = (127) +0. 572

(0. 037) ST07 479 117 447 eq 3 table 7-26

10 ST5Y

s.d. = +5431 = (254) +0. 202

(0.074) ST07 954 3.7 508 eq 2 table 7-30

11 STXY

s.d. = +5036 = (303) +0. 161

(0. 087) ST07 1035 1.7 562 eq 4 table 7-34

12 STIY

s.d. = +3383 = (293) +0.564

(0. 057) ST28 695 49 535 eq 3 table 7-18

13 STIM

s.d. =+3123 = (292) +0. 692

(0. 057) ST28 690 74 572 eq 2 table 7-22

14 STIA

s.d. =+2026 = (186) +0.640

(0. 036) ST28 448 156 447 eq 3 table 7-26

15 ST5Y

s.d. =+3592 = (367) +0. 494

(0.071) ST28 867 24 508 eq 2 table 7-30

16 STXY

s.d. =+3036 = (432) +0.495

(0. 083) ST28 948 18 562 eq 4 table 7-34

17 STIM

s.d. =+754 = (243) +0. 941

(0.038) STIY 452 298 572 eq 2 table 7-22

18 STIA

s.d. = +2351 = (321) +0.467

(0.051) STIY 598 42 447 eq 3 table 7-26

19 ST5Y

s.d. = +8977 = (276.5) +0.963

(0. 044) STIY 515 240 508 eq 2 table 7-30

20 STXY

s.d. = -353 = (337) +0.949

(0. 053) STIY 611 158 562 eq 4 table 7-34

21 STXY

s.d. = +808 = (423) +0.719

(0. 063) STIM 781 65 562 eq 4

table 7-34

22 STXY

s.d. = -181 = (218) +0.956

(0.036) ST5Y 452 357 562 eq 4 table 7-34

6.3. Early Strength Versus Composition of

tlie Cement, and the Prediction of Strength

at Later Ages

In order to evaluate the relative merits of the

use of the compressive strength at an earlier age

versus the use of the physical and chemical

properties of the cements in making predictions of the compressive strength of cement mortars at a

later age, a comparison was made of the S.D.

values obtained by the two methods. The S.D.

values obtained from the strength relations dis- cussed in the previous subsection and those obtained by use of the combinations of chemical and

physical independent variables are both presented

in table 7-76.

Referring to table 7-76 it may be noted that the

S.D. value for eq 1 was the same as that obtained

in eq 3 of table 7-14. From this it may be inferred

that the 28-day compressive strength values can

be predicted equally well by either method.

Equations 6, 14, 17, and 22 of table 7-76 had

lower values than those obtained in corresponding

previously calculated equations. Equation 6 re- lated the 28 to 7-day strengths, eq 22 the 10 to 5-year strengths, eq 17 the 1-year moist-air to water-stored strengths. All of these test ages were

adjacent to each other. Equation 14 related the 1 year strength of the air-stored specimens to the

28-day compressive strength. The 1-year air-stored

specimens were cured 3 weeks in water, 1 week at the start and 2 weeks before the compression tests, and were therefore hydrated for approximately

the same time as those cured in water for 28 days.

All of the other equations of table 7-76 had

higher S.D. values than when the compressivestrength values were fitted to combinations of independent variables—the chemical and physical

properties of the cements. Many of these pairs of

S.D. values were approximately equal, but information which would indicate statistical significance

is not available. However, since the equation

derived from chemical and physical properties

include many more variables, their S.D. values

would have to be considerably lower than those

for the equations in table 7-76 to indicate the same prediction value.

The fact that the S.D. values of so many of the

equations derived with the use of the chemical

and physical properties of the cement were lower

than those derived from the relation to earher

strength results indicates, that in many instances

it might be possible to use the chemcial and

physical properties to make a rough prediction of the compressive strength at the later test ages.

6.4. Coefficients, and Their Significance, of

the Major Potential Compounds, of Other

Commonly Determined Variables and of

the Trace Elements at Different Test Ages

A series of tables has been presented indicating

the variables found to be significant for the compressive strength at each of the test ages from 1 day

57
to 10 years. In view of the fact that it is difficult to follow the trends of the coefficients with the age of

test, a summary, Table 7-77, has been prepared.

For this comparison, a single equation was selected

from each of the tables previously presented for

the NAE cements at the various test ages and now

presented in table 7-77. The equation selected was, in each case, one in which one or more of the

potential compounds, air permeability fineness,

and trace elements were included as independent

variables.

The equations are presented vertically instead of horizontally as was done in the previous tables.

For example,

constant

+

+

C2Z2 +

Under each coefficient is presented the coef./s.d.

ratio instead of the s.d. value in the original equations.

Table 7-77. Coefficients, coef./s.d. ratios, and calculated ranges of contributions of independent variables associated with compressive strength values at different ages for NAE cements

Equation 0 2 3 4 4 3 5 3 4

Table 7-3 7-7 7-11 7-15 7-19 7-31 7-35 7-23 7-27

STOl ST03 ST07 ST28 STIY ST5Y STXY STIM STIA

Constant -2071 -2935 -2813 +1010 +6820 +6505 +7774 +6502 +2130

C3A, coef - +40.7

3.6

570 +39.5

8.6

1778

+70.2

5.3 983 +65.2

9.9

2484

+74.1

3.6

1037 +45.5

5.7

2048

-82.7

5.4

1158

-85.4

5.0

1196

-126.2

5.4

1767

-57.9

3.2

811

Coef./s.d Calculated ranges*-.- _--

C3S, coef- +19.2

8.2

864

+29.5

4.8

1328

Coef./s.d Calculated range _ _ _

C2S, coef- +17.8

2.5 801

+19.6

2.5 882 -53.7

2.0

806 +0.31

2.9 930 -224

8.1 4480

Coef./s.d __ Calculated range CjAF, coef- +42.0

1.6 630 +0.71

6.6 2130 -101.5

3.8

2030

Coef./s.d Calculated range APF, coef

Coef./s.d Calculated range Air 1:4 Mortar, coef

Coef./s.d Calculated range—- -

SO3, coef-

+0.55

14.5 4350 -18.8

2.2

376 +257

4.6

463 -188

+0.78

10.8 3248 -70.3

4.4

1406 +446

4.

1

802 -252

4. 5 756

+0.89

10.2

2670 -75.5

3.9

1510 +313

2.5

563 -362

5. 2

1086

+0.37

4.3

1110 -95.0

3.6

1900

+0.47

5.4 1410

-170. 2 6.9 3404

+0.61

4.7

1530 -139

4.8 2780 +270

1.5 486

+0.43

4.7

1290 -89.6

4.0

1792 +494

3.8

889

Coef./s.d Calculated range

Loss, coef.-- -460

4. 6

1380

-713

2. 0

2139

Coef./s.d--- 6. 2 Calculated range 564

Insol., coef. - . - - - - - -216 -928

2.7 928 -64.7

1.8 324

-986

2.6 985

-655

2.2

655 +80.3

2.3 402

Coef./s.d - 1.8 Calculated range - 216 MgO, coef—- -26.1

0.9

131 +524

2.9 576

-82.9

2.0

414

Coef./s.d Calculated range K2O, coef +399

5.4 +3762.6

414

Coef./s.d Calculated range. . - . 439 NajO, coef-- - - -- - --- -858

3.0

601

-1030

3.8

721

-1256

4.

1

879

Coef./s.d-- Calculated range - . - - -3540

3.1 708

Coef./s.d Calculated range

Co, coef- -- -71700

2.0

717 -22000

2.0 440

-68600

1.8

585

-49700

1.3 497

Coef./s.d Calculated range

Cr, coef--- - -- +7480

1.1 160

+18300

1.7 366Coef./s.d Calculated range -. See footnote at end of table.

58
Table 7-77. Coefficients, coef./s.d. ratios, and calculated ranges of contributions of independent variables associated with compressive strength values at different ages for NAE cements—Continued

Equation 2 2 3 4 4 3 5 3 4

Table 7-3 7-7 7-11 7-15 7-19 7-31 7-35 7-23 7-27

-7190

1.2 340 —500

1.

2

600

—6226

1.4

311

Coef./s.d - Calculated range Ma, coef. —537

2. 2

537

—576

1. 6 576Coef./s.d Calculated range

Ni, coef.-- -- - +5960

1.4

119 —275

2.

1

137

+19300

1. 5 386Coef./s.d Calculated range.. . -

P, coef +990

2.2

445

Coef./s.d Calculated range... - . Pb, coef +9260

1.

5

463

Coef./s.d - . - Calculated range Rb, coef —63000

2. 7 630

—60000

2. 7 600

-99800

3.9

998 —1460

2.

5

867

Coef./s.d. --. ... - - - ... Calculated lange

SrO, coef. . - --- -— —394

2.

3

234

—911

2.

7

541

—558

1. 4 331

—1130

1.

8

671

-990

1.6

588 +3730

1.6 746 +2590

2. 2

1245

Coef./s.d Calculated range

Zn, coef.. ... +1990

1.5 398 +1740

1. 7 870

Coef./s.d Calculated range

Zr, coef +1720

1. 5 860

+2220

2.

1

1110

Coef./s.d Calculated range V, coef +3200

1.9 320Coef./s.d Caclulated range _. _ _ .

•The calculated range was computed from the range of values for the cements times the coefficient for each independent variable.

Also presented in this table are values called

"calculated range." These values were obtained

by multiplying the coefficient for each of the

variables by the difference between the high and

low value for each of the respective variables

found with the cements used in this investigations.

In some instances, as for SO3, insoluble residue

and ignition loss, the values found were less than

are permitted by present specifications for portland

cements.

The first seven equations in table 7-77 are for

the compressive strength of water-stored specimens

from 1 day to 10 years. The coefficients for C3A

were positive and highly significant at 3, 7 and

28 days, but at 1, 5 and 10 years, the coefficients were negative, and again highly significant.

The coefficients for C3S were positive vnih. an

increase of the coef./s.d. ratio to 7 days,—then a decrease at 28 days, after which the coef./s.d.

ratio was less than one. In this series of tests, the

C2S did not show any evidence of significance

until the 5- and 10-year tests. The coefficient for C4AF was positive but of doubtful significance at

28 days but the sign was negative in the equation

for the 10-year tests. The coefficients for fineness were positive at all ages. The variable was most significant at the

early ages, but less significant at later ages. On

the other hand, the air content of the 1 :4 mortar,

with a negative coefficient became more highly

significant at the later test ages,—5 and 10 years. The SO3 was significant only up through 7 days,

but Loss was signfficant up through 1 year, and

Insoluble residue only at the later ages. The MgO

was of doubtful significance at 5 years for the waterstored specimens, and more significant at 1 year

for the moist-air-stored, and the air-stored speci- mens. The coefficient was negative in the ST5Y

and STlM equations, and positive in the STlA

equation.

The coefficients for K2O were positive and were

significant only at 1, 3, and 7 days. The coeffi- cients for Na20 were not significant at the early

ages but were at 1, 5, and 10 years and the coefficients were negative. (It should be noted,

however, that in equations for SG(1), SGK(l),

59
SG(2), SGR(2), SG(3), SGR(3), SG(4), SGR(4),

in previous tables, the coefficients for both_Na20

and K2O were significant and were negative in

all the strength-gain, and the strength-gain-ratio

equations. No explanation can be offered for these

differences, but the alkalies will be discussed

further in a later subsection.

In table 7-77 there were only two instances

where the coef./s.d. ratios for the other trace elements, Ba, Co, Cr, Cu, Mn, Ni, P, Pb, Rb,

SrO, V, Zn, and Zr were greater than 3. The signs

of the coefficients were consistent where the variable occurred and was significant in more than

one equation. The coefficients for SrO were significant in equations for one and three days and

1-year moist cured and possibly significant at 7 and 28 days. (SrO was not significant in the SG

nor the SGR equations.) The coefficients for Zr were significant at 1 and 10 years, and

possibly at 28 days and 5 years but not at the

earlier ages, and the coefficient for Zn was not

highly significant at any age. The coefficients of the rest of the trace elements did not show strong

evidence of signfficance.

The use of trace elements found to be significant in the equations for compressive strength

resulted in a significant reduct'on in the S.D.

values at all ages except for the 7-day tests. There

is no apparent reason for the difference in behavior at the 7-day test age.

6.5. Coefficients, and Their Significance, of

the Major Oxides at Dii¥erent Test Ages

Equations were presented for the compressive

strength at various test ages as related to the

major potential compounds with other variables,

and to the major oxides with other variables. There

were only a few instances where the other variables were not the same or had different coefficients or

coef./s.d. ratios when the oxides were used than

when the compounds were used in the calculations.

The S.D. values Avere approximately the same in

both cases in comparable equations for each of the

test ages. As in subsection 6.4 the coefficients and coef./s.d.

ratios for the oxides were different at different

ages. The coefficient for CaO was positive and the

coef./s.d. ratio increased from 1 to 3 to 7 days,

decreased some at 28 days and was not significant at 1, 5, and 10 years. The coefficient for Si02 was

negative up through 28 days,—was not significant at 1 year,—then became positive at 5 and 10

years. The coefficient for AI2O3 was negative at 1 and 3 days, and at 1 year, but was not significant at the other ages for the water-stored specimens.

The Fe203 was significant at 1 and possibly 3

days with a negative coefficient,—was not significant at 7 and 28 days,—then the coefficient

became positive with increasing significance at 1, 5, and 10 years. The trends of the coefficients,

and changes of the signs of the coefficients for Si02 between 28 days and 5 years, or for Fe203

between 3 days and 1 year are of interest and value

m mdieating the dominant oxides associated with

early strength differences of mortars made of the

various portland cements, and those stored in

water for an extended period of time.

6.6. The Effect of Alkalies in Portland Cement

on Compressive Strength

It was previously noted that the coefficient for K2O was significant in equations for the 1-, 3-, and 7-day compressive strengths with positive

coefficients, and NajO in the equations for the

1-, 5-, and 10-year compressive strengths with

negative coefficients. It has been reported, and is generally accepted, that the K2O may be in the

substituted C2S, (KC23S12), and also in solid

solution as a sulfate. Some NajO is generally

befieved to be in a substituted C3A, (NCgAa),

with any excess in a sohd solution, possibly in the

form of a sulfate. Of the other elements in this group, Li was possibly significant in equations for SR(1). Rb was

significant in equations for STlY, STlM, ST5Y,

and SR(1) and possibly for SG(1), SG(2), and

SGR(2). Information is not available on the

compounds these elements are associated with or

if they also occur in the solid solutions. No

statistical tests were made to determine possible

interaction of the different alkalies with the other

independent variables in the equations. It does

appear, however, that more attention should be

given to the effect of the individual alkalies on

properties other than the alkali-aggregate ex- pansion.

6.7. Compressive Strength and Heat

of Hydration

It was indicated in a previous section of this

series of articles [13] deafing with the heat of hydration that there was a significant relationship between the 7- and 28-day heat of hydration

and compressive strength, but no relation between

strength and the 1-year heat of hydration.

At 7 and 28 days C3A and C3S were important

among the compounds associated with both heat

of hydration and compressive strength. In equations for the 1-year heat of hydration, the coefficient for C3A was positive, but it was negative

in the equations for 1-year compressive strength.

The C3S and C2S, although contributing to the 1- year heat of hydration, did not appear to affect the 1- year compressive strength values obtained with

the different cements. The C4AF content contributed to the heat of hydration at 28 days and

1 year, but showed a significant effect on strength

only at one day (eq 3, tables 7-2 and 7-3).

Of the other commonly determined variables,

the loss on ignition had a relatively large effect at all ages through one year in both the heat of hydration tests and the strength tests. The fine- ness of the cement was a contributing factor in both heat of hydration and strength, but it appeared to have a more dominant role in the

60
compressive strength tests. The coefficient for SO3 was positive and significant in equations for both the 7-day heat of hydration and strength but

in neither test was the coefficient significant at the later ages. The coefficient for K2O was positive and signifi- cant in equations for both 7-day heat of hydration

and strength, but was not significant at 28 days

or 1 year in equations for these two properties.

The coefficient for NajO was significant and had a negative sign in both the 1-year heat of hydration

equations and the 1-year compressive strength

equations, but was not significant at the earlier ages. The air in the 1:4 mortars was associated

with the compressive strength of the 1 :2.75 mortars

at all ages, but this variable was not significant

in equations for heat of hydration.

Some trace elements were also associated with

the heat of hydration and with the compressive

strength. The signs of the coefficients were generally the same in equations for both properties, but

in many instances the effect of some trace elements were masked at some ages. For example an in- crease in Cu was associated with lower heat of hydration at 7 and 28 days and 1 year but was

not highly significant in any of the strength equations. The Zr content appeared to make a signifi- cant contribution to the 7- and 28-day heat of hydration, but not to the 1-year heat of hydration.

The Zr content was possibly also associated with

the compressive strength values of the waterstored specimens at 28 days and later ages. An

increase in Zr when significant was associated with an increase in strength. The coefficient for SrO

was significant and negative in equations for the

28-day heat of hydration.

In the equations for compressive strength, the

coefficient for SrO was significant and negative

at one and three days water-stored and 1-year

moist-air-stored and was possibly significant at 7 and 28 days and 10-years water-stored but not

significant for the 1-year air-stored specimens. An

increase in P was associated with lower heat of hydration values at all ages. The coefficient for P

was negative in equations for 1-day compressive

strength, and positive in equations for the compressive strength at 1 year for the moist-air-stored

specimens. At other ages there was no evidence

for any effect of P. (The number of cements with

reported values for P was small and, as previously

indicated, values below the lower reporting limit were listed as having 0% of the element. This

makes any values for P doubtful.)

Of the other trace elements, the coefficient for Cr was significant in equations for the 7-day heat

of hydration and 28-day compressive strength.

The coefficient for Co was significant in equations

for both 28-day heat of hydration and compressive

strength and possibly also in equations for the

1-year compressive strength. The coefficients for V and Ba were significant in equations for 1-year

heat of hydration, but not in equations for 1-year

compressive strength. The coefficients for Rb and

Mn were not significant in equations for heat of

hydration, but Rb was significant and Mn was

possibly significant in equations for 1-year compressive strength.

There appear then to be a number of instances

where the effect of a variable on compressive

strength is also significant in the equations for the

heat of hydration. There are also differences, for example the sign change of the coefficient for C3A

in the equations for compressive strength, and the

lack of significance of C3S and C2S in the equations

for 1-year compressive strength. Another large

factor affecting the compressive strength is the

air entraining characteristics of the cements.

6.8. Air Permeability and Turbidimeter

Fineness Values and Compressive Strength

The importance of the fineness of grinding of Portland cement clinkers has been recognized in

specification requirements for many years. In

the present investigation it was also found to be

one of the important variables associated with, the

compressive strength of cements of different

compositions especially at the earlier test ages.

It was noted that in relating the compressive

strength at the different ages to the combinations

of independent variables, that the equations

using the turbidimeter fineness values usually

had lower S.D. values than comparable equations

using the air-permeability fineness values. Equations for strength-gain, strength-gain ratios, and

strength ratios had smaller differences in the S.D.

values when using the fineness values obtained by

the two methods in the equations.

The average ratio of the fineness values determined by the two methods Avas 1.88 with an

estimated standard deviation of 0.16. It has been

reported (Lea-Desch p 331) [7J that the APF/

WAGN ratio varies with the fineness of the

cement and the gypsum content. It is commonly

knoAvn also, that the ratio for types II, IV and V

cements may differ appreciably from the ratio

obtained with type I cements.

Using the same statistical techniques employed

in the rest of this series of, articles, 2 equations were obtained as follows:

(1) APF/WAGN=-M. 422

s.d.= ( 0.043;

+0. 0129 C3A

(0. 0027)

+0. 0776 SO3

(0. 0254)

+0. 1670 Loss

(0. 0155)

(2) APF=-621

s.d.= (136)

-t-1. 720 WAGN

(0. 068)

+ 17. 79 C3A

(5. 39)

+207. 9 SO3

(50. 9)

+305. 2 Loss

(28. 9)

276 694 0-68—

5

61
An S.D. value of 0.105 was obtained for the first equation. The reduction of variance resulting

from the use of the added variables was 57 with

4:175 degrees of freedom. In the second equation

the S.D. value was 198, the "F" value 221 with

5:174 degrees of freedom. The coef./s.d. ratios for

all of the independent variables in the two equations Avere highly significant. Other equations,

not presented, indicated that the trace elements

Zr, Cr, and Rb may also be associated with the

fineness and fineness ratio. The C3A, SO3, and

Loss were, however, the most significant variables.

High values of C3A, SO3, or loss on ignition are

all associated with low specific gravity of the

Portland cements. A specific gravity less than the

assumed value of 3.15 would result in a specific

surface value somewhat greater than would be

obtained if the correct specific gravity value were

used Avith both the turbidimeter and air-permeability apparatus."

When the independent variables C3A, SO3, and

loss on ignition were significant in equations relat- ing the compressive strength at the different ages

to the various independent variables, it was noted

that numerical differences in coefficient and coef./

s.d. ratios occurred Avhen "Wagner turbidimeter

fineness values were substituted for air permeability values. In the case of Loss these differences were large and highly significant at ages less than

1 year. For the other two variables, the differences were much smaller, but may possibly indicate a

significant effect at some ages.

6.9. Compressive Strength and Other Independent Variables

The previous subsection presented information

relative to the interrelation between fineness values

and other determined variables, C3A, SO3, and

loss on ignition. It is probable that some of the

so-called independent variables are not truly

"independent." Although the water-requirement

for the mortars of the different cements, for in- stance, was not found to be a significant variable

in the compressive strength tests, it was pre- viously shown in section 2 of this series of articles that this property is also dependent on many of the variables associated with compressive strength.

(See table 2-6 p 18, 19) [9].

7. Summary and

(1) Compressive strength tests were made on

1 :2.75 (cement to graded Ottawa sand) mortar

cubes of standard consistency at ages from 24 hr

to 10 years. The tests were made on 199 portland

cements of different types and from different

" The rate of settling of the particles is a function of the difference in density

of the cement and the liquid in which it is dispersed in the tubidimeter test. The permeability function, e>PI(l-e), where e=porosity, in the air permeability test for fineness is probably more sensitive to differences in the specific gravity of the cements. With the turbidimeter test, a low-specific-gravity cement would settle more slowly and result in a "high" fineness value. With

the air-permeability fineness test, the actual porosity of the test bed would

be less than the calculated value which would also result in a"high" fineness value.

Also in table 7-63 of this article, there was some indication (on the basis of one parr of equations) that the "air in the 1:4 mortar" may be a

variable which may interact with other independent variables. The air content was not determined

for the 1:2.75 mortars used for the compressive

strength tests and it was necessary to use the

values for the percentage air entrained in 1:4 mortars. The correlation between the air content

values of the two mortars is far from perfect, and

better knowledge of the air content of the test mortars may have resulted in better fit of the

test data to the calculated relationships. The air- entraining characteristics are apparently of great

importance, even with the nonair-entraining ce- ments, and should be recorded in any future work

of this nature. There are also other interrelations in the portland cement composition, as, for example, the

C3S and C2S, or the C4AF and C3A. Wlien the

potential C3S content in a portland cement is increased, it is usually at the expense of the potential C2S content. When used in a multivariable

regression equation, one or the other may have a dominant effect. If both are used in an equation,

the significance of one or both may disappear.

Previous studies of the strength-producing

characteristics of laboratory-prepared compounds

of C3S and C2S have established the fact that both

contribute to a major extent to the compressive

strengths although the rates of strength contributions are different. It may seem unusual, therefore,

that neither the C3S nor the C2S were significant

in multivariable equations relating the different

independent variables to the compressive strength

at 1 year for the water-stored specimens, for example.

One way of getting around difficulties mentioned

above is the interpretation of the relationships of the various "independent" variables to differences

in the compressive strength values attained by

the portland cements. This interpretation does

not detract from the usefulness of the equations

presented. It does help to explain why different

cements attain greater strength than others. It also indicates that the extension of research on

the modifying effects of certain trace elements on

such properties as compressive strength may be

fruitful. Conclusions

mills. All specimens were stored in water until

time of testing, except that 1-year tests were also made on specimens stored at 95 to 100 percent

relative humidity and on specimens stored in laboratory air at 50 percent relative humidity for 49 of the 52 weeks.

(2) The average compressive strength values

for water-stored specimens for the different types

of cement increased up through the 1-year tests, but the averages were somewhat lower at the time

of the 5- and 10-year tests.

62
(3) The average compressive strength of the

1-year air-stored specimens, tested after resaturation, was near that of the 28-day water stored

specimens. The average compressive strengths of the 1-year moist-air stored and the 1-year waterstored specimens were also nearly the same.

(4) The frequency distributions of the compressive strength values at the different test ages

indicated that a range of values was obtained for each of the types of cement, and there was considerable overlapping of the values obtained for

the different types.

(5) Computations of multivariable equations by

a least-squares method were used to determine

the chemical and physical properties of the

cements which were associated with the compressive strength values at the various ages, the

strength gain between various ages, the compressive-strength-gain ratios, and various strength

ratios. The equations were computed for all cements for which minor constituents and trace elements had been determined, and for the nonair- entraining cements within this group. The equations were computed using as independent variables, either the major potential compounds, or the major oxides, each with other commonly

determined variables found to be significant.

The following observations relate to the equations for water-stored specimens made of nonairentraining cements as summarized in table 7-77.

(5.1) The major potential compounds found to be associated with differences in compressive

strength were not the same at the different test ages or after different storage conditions.

An increase in the C3A was associated with

higher compressive-strength values at 3, 7, and

28 days, and with lower compressive-strength

values at 1, 5 and 10 years. An increase in the C3S was associated with

higher compressive-strength values up to 28 days,

but the coefficient for C3S was not significant at the later ages. An increase in the C2S was associated with

higher compressive-strength values only at 5 and 10 years. (At 1 year neither C3S nor C2S had

significant coefficients.)

An increase in the C4AF showed a barely significant association with lower strength values at 10

years.

(5.2) Other commonly determined variables were also associated with the compressive-strength

values at the different test ages, and the contribution and significance of these variables were

different at different test ages. An increase in fineness was associated with

higher compressive-strength values at all test ages but to a greater extent at the early ages. An increase in the air content of the 1 :4 mortar

(the air contents of the 1:2.75 mortars were not

determined) , was associated with lower compressive

strength values at all ages, and most significantly

at' the later test ages, 5 and 10 years. An increase in SO3 was associated with higher

compressive strength values only at 1, 3, and 7 days.

An increase in loss on ignition was associated

with lower compresisve-strength values at all test ages up to 1 year. An increase in the insoluble residue was as- sociated with lower compressive-strength values

at 5 and 10 years, and possibly at 1 day.

An increase in MgO was associated with a higher

compressive strength with the 1-year air-stored

specimens and possibly with a lower compressive

strength for the 1-year moist-air-stored specimens

and the 5-year water-stored specimens.

An increase in K2O was associated with higher

compressive strengths only at 1, 3, and 7 days.

An increase in NajO was associated with lower

compressive strength values at 1, 5, and 10 years, but not at early ages. (An increase in both Na20

and K2O was associated with lower strength gain

and strength-gain-ratios in all equations.)

(5.3) The use of other minor constituents and

trace elements resulted, in most equations, in

significant reductions in the estimated standard

deviation values. The one exception was in equations for the 7-day compressive-strength values.

The coefficients for the trace elements were generally not highly significant, and, in equations cal- culated for the "odds" and "evens" in the array of

cements, many were not significant in the smaller

groups.

In general, increases in Mn, Rb, and SrO were

associated with lower compressive-strength values

at one or more of the test ages, and an increase in

Zr with higher values at some later test ages. There were also indications of a possibility that

Ba, Co, Cu, Ni, Pb, V, and Zn might also have some effect.

(6) Equations calculated using the major oxides,

other commonly determined variables and trace elements resulted in estimated standard deviation

values of about the same magnitude as obtained

with the use of the major potential compounds.

There were a number of exceptions, but in general,

the same other commonly determined variables

and trace elements were significant as when the

major compounds were used in the equations. As

was found for the major compounds, the coeffi- cients of the major oxides as well as the significance

of the coefficients were not the same for the compressive strength values determined at different

ages. An increase in CaO was associated with higher

compressive strength values at 1, 3, 7, and 28

days, but not at later ages. An increase in Si02 was associated with lower

compressive strength values up through the 28-

day tests and with higher compressive strength

values at 5 and 10 years. An increase in the AI2O3 was associated with

lower compressive strength at 1 and 3 days, but was not significant for the water-stored specimens

at other test ages.

63
An increase in Fe203 was associated with lower

compressive strength vakies at 1 and 3 days and

with higher compressive strength vakies at 5 and

10 years and possibly at 1 year.

(7) Variables associated with the compressivestrength values of nonair-entraining cements were

also associated in equations for the combined air- entraining and nonair-entraining cements. The

significance of the coefficients of the air-content

variable was greater when the air-entraining ce- ments were included. Some differences were noted

in the values of the coefficients of corresponding

variables in the equations for the AE+NAE ce- ments and those in equations for the NAE cements

alone, but they were usually small compared to the estimated standard deviations of the respective

coefficients.

(8) The equations for gain in compressive

strength between different test ages, for the

strength-gain ratios, and strength ratios did not

have the same significant independent variables

as in the equations for the compressive strength

at the corresponding test ages. Some independent

variables found to be significant in one or both of the equations relating the variables to the strength

at each of two ages were not significant in ratios or differences of the strength values. It was noted,

however, that in some equations for ratios etc., other variables, not significant in the equations

for the strength at two test ages were significant

in the equations for ratios or differences.

(9) Although the average compressive-strength

values of 1-year water-stored and moist-air-stored

specimens Avere nearly the same, the specimens of a majority of the cements stored in water had lower

compressive strength values than those stored at a high humidity. Equations were computed for the ratio of the compressive-strength values after

water storage to those after moist air storage, as related to combinations of independent variables. Increases in C3A, C3S, C4AF, SO3, and Na20 and

possibly P were associated with lower strength

ratios, and increases in MgO, Zr, V, and lib and

possibly Ti Avere associated with higher strength

ratios. (10) Although the average 1-year compressive

strength of the air-stored specimens was about

equal to the average 28-day compressive strength

of water-stored specimens, this relationship was

not true for all cements. The compressive strengths

of the air-stored specimens were lower for 57 of the 199 cements. Increases in C3A, C3S, C4AF,

and Ba were associated with lower (1-year-air/

28-day-water) strength ratios, and increases in

MgO, Loss, air content, Co, Pb, Mn, and V, and

possibly SO3 and Cr with increases in the strength

ratio. (11) The use of various independent variables

associated with the chemical and physical properties of the cements in equations resulted, in many instances, in lower estimated standarddeviation values than were obtained by relating

the compressive-strength values at a later age to those at an earlier age.

(12) A comparison was made of the variables

associated with the heat of hydration at 7 and

28 days, and 1 year, and the variables associated

with the compressive-strength values at these

ages. There were a large number of instances where

the independent variables had parallel effects in the two tests at the respective test ages. Some of the more important factors which may cause a lack of agreement between the 1-year heat of hydration and the 1-year compressive-strength

differences are the change of sign for the coefficient for C3A, and the fact that C3S and C2S contribute

to heat of hydration, but not to compressive

strength differences. The air-entraining characteristics of the cements were associated with the

compressive-strength values at all ages, but not

Avith the heat of hydration.

(13) The use of the Wagner-turbidimeterfineness values rather than the air-permeabilityfineness values usually resulted in lower estimated

standard-deviation values in the multivariable

equations for compressive-strength values at the

different ages. The effect was not so pronounced

in equations for strength-gain or for strength-gain

ratios. The differences in ratios of the two fineness

values are dependent to a large extent on the C3A

and SO3 content and on the loss-on-ignition values,

all of which may have an effect on the specific

gravity of the cement. The interrelations of these

"independent" variables were reflected to some

extent in the coefficients of these variables when

used in the equations.

Acknowledgments are made to the former

heads of branch laboratories of the National

Bureau of Standards at Allentown, Pa., Denver,

Colo., San Francisco, Calif., and Seattle, Wash.,

G. Stiller, O. H. Cox, O. C. Marek, and Frank

Winblade, respectively, as well as their associates,

and to D. N. Evans, former head of the Washington Laboratory and his associates for collecting

the cements, making the many tests, collecting,

checking, and compiling the data.

64
8. References

[1] Federal Specifications SS-C-192, Cement, Portland.

[2] Standard Specifications for Portland Cement, ASTM

Designation C-150.

[3] P. H. Bates and A. A. Klein, Bureau of Standards, Tech. Paper 78 (1917).

[4] H. Woods, H. R. Starke, and H. H. Steinour, Eng.

News Record 109, 404, (1932), and 110, 431, (1933).

[5] J. H. Welch and W. Gutt, Proc. Fourth International Symposium on the Chemistry of Cement. Washington, 1980, p. 59.

[6] M. O. Withey and K. F. Wendt, Proc ACI 39, 221

(1943).

[7] F. M. Lea and C. H. Desch, The Chemistry of Cement

and Concrete (St. Martin's Press, New York, 1956)

.

[8] R. L. Blaine, H. T. Arni, and B. E. Foster, NBS

Building Science Series 2, Section 1 (1965) p. 1. [9] 11. L. Blaine, H. T. Arni, and R. A. Clevenger, NBS

Building Science Series 2, Section 2, 1965 p. 13.

flO] R. L. Blahie, Leonard Bean, and Elizabeth K. Hubbard, NBS Building Science Series 2, Section 3, p. 33.

[11] Federal Specifications SS-C-158c Amendment 1, Cements, Hydraulic, Methods for Sampling, In- spection and Testing. May 25, 1954.

[12] Tentative Method for Test for Compressive Strength

of Hydraulic Cement Mortars (using 2 in. cube

specimens) ASTM Designation C109-54T.

[13] R. L. Blaine, H. T. Arni, NBS Building Science Series No. 5, Interrelations Between Cement and Concrete

Properties, Part 2, Section 5, page 27.

65

Section 8. Compressive Strengtli of Steam-cured Portland Cement

Mortars

R. L. Blaine, H. T. Arni, and M. R. DeFore

The relationships between the chemical and physical characteristics of 161 portland cements and the compressive strengths of 2-inch mortar cubes made from those cements

after both low- and high-pressure steam, as well as moist-air curing, were studied by computing multivariable regression equations with the aid of a digital computer, and determining which of the independent variables appeared to have a significant relationship to the compressive-strength values. An increase in C3A, SO3, and K2O each appeared associated with higher compressive strengths with the low-pressure-steam-cured specimens but not with 28-day strengths of the 23 °C moist-air-cured specimens. Increases of C3A, C3S, C2S,

SO3 and fineness were all associated with higher strength values when autoclave curing was

started after 5 hours, but when started after 24 hours, variations of neither C3A nor C3S

appear to have any effect. The use of certain of the trace elements in the equations together

with commonly determined variables resulted in a reduction in variance although the coefficients of the individual trace elements were, in most instances, not highly significant.

Key Words: Accelerated curing of cements, autoclave curing of portland cement

mortars, chemical composition, compressive strength of portland cement,

compressive strength of steam-cured cements, mortars, steam curing of portland cement mortars, trace elements. Contents

Page

1. Introduction 67

2. Materials 68

3. Tests and nomenclature 69

3.1. Series I, curing started at 5 hr 69

3.2. Series II, curing started at 24 hr 70

3.3. Series III, normally cured specimens 70

3.4. Other notations and comparisons 70

4. Statistical treatment 70

5. Results of tests

5.1. Compressive strength at 28 days of moist-air- cured specimens (WAGR) 71

5.2. Compressive strength of specimens moist- cured for 2 weeks then air-dried for 2 weeks (WAMA) 73

5.3. Compressive strength of mortars cured with

low-pressure steam after 5 hr moist curing

and later dried in laboratory air (STGR)-_ 76

5.4. Compressive strength of specimens cured with

low-pressure steam after 24 hr, tested wet (STMA) 78

5.5. Compressive strength of mortars cured with

high-pressure steam after 5 hr moist storage

(AUGR) 78

Page

5.6. Compressive strength of mortars, high-pressuresteam-cured after 24 hr, and tested after drying (AUMA) 81

6. Discussion

6.1. Variables associated with strength after differ- ent curing conditions 84

6.2. Relationship of compressive strength values

of 1:3.525 (cement to silica) mortars when

cured under different conditions 86

6.3. Estimated standard deviation of duplicate

tests 90

6.4. Relationship of compressive-strength of mortars in this series to those of 1:2.75 (ce- ment to sand) mortars presented in the previous section 90

6.5. Mix proportions 91

6.6. Compressive strength versus time of set 92

6.7., Compressive strength of steam-cured mortars

versus early strength of 1 :2.75 (cement to sand) water-cured mortars 95

6.8. Linearity of relationships 96

7. Summary and conclusions 96

8. References 97

1. Introduction

The first reported commercial use of hydrothermal means to obtain a more rapid strength

development of concrete was, according to one

report [1],^ by James Rowland in 1868. Since that

time a great many investigations have been made,

and reports published, relative to the strength and

other properties of steam-cured concrete. Among

the early contributors were Wig [2], Wig and

Davis [3], Woodworth [4], Pearson and Brickett

> Figures in brackets indicate the literature references at tlie end of tills section.

[5], and Thorvaldson [6]. The comprehensive

investigation by Menzel [7] helped to establish

better commercial application of high-pressuresteam-ciu"ing of concrete products.

Shideler and Chamberlin [8], Nurse [9], and

Saul [10] were among the early contributors to a systematized knowledge of the effects of steam

curing at atmospheric pressiu-es.

Along with the practical aspects of the commercial use of steam curing, there has been a great

amount of investigation of the chemical reaction

67
involved and the hydrates formed under the

different conditions. Studies by Kalousek [11] and by Aitken and Taylor [12] as well as many

others have contributed greatly to our knowledge

both of the reactions and reaction products formed.

It would not be i^ossible in this article to give

reference to, nor evaluate all the contributions

which have been made. The many contributions

to both the practical and theoretical aspects of

hydrothermal or steam-curing of cement and

concrete products have been listed and discussed

in the international symposia [6, 11, 12] as well as

in books on the chemistry of cement by Bogue

[13], Lea and Desch [14], and more recently by

Taylor [15].

_ Accelerated curing of concrete in steam at atmospheric pressure, or at elevated temperatm'es

and pressures is being used more extensively

than ever before. The ACI report previously

cited [1] summarized the knowledge in the field of high-pressure-steam curing and presented

recommended procedures for commercial production. Another ACI report [16] presented similar

information relative to low-pressure-steam curing.

Both reports also present a large number of ref- erences. Many of the variables involved have been

studied but there does not appear to be much in- formation available on the effect of cement composition on the properties of the steam-cured

products, especially those cured in high-pressure

steam. One of the objectives of the present study was to determine, by statistical means, some of the commonly determined variables associated

with the relative compressive strengths of cements

of different compositions Avhen cured -with both

low- and high-pressure steam. Included also was a study of the possible effects of the trace elements

in the cements.

A second objective in this series of tests relates

to accelerated strength tests of portland cement

mortars. Curing of the mortar and concrete at

higher than normal temperatures has been proposed (according to Taylor [15] by King [17] and

Ackroyd [18]) as a means for forecasting the longterm strength of normally cured concrete. A

recent symposium [19] by correspondence con- ducted by RILEM (The International Union of Testing and Research Laboratories for Materials

and Structures) has a series of eight articles by

different authors relative to the use of "accelerated

hardening of concrete with a view to rapid control

test." Further information appeared desirable

before such a method of testing can be adopted.

The recommended practices, both for lowpressure-steam curing [16], and high-pressuresteam curing [1] have suggested time-schedules

for the various commercial operations which are

difficult to carry out in a laboratory normal

work day. These time schedules were followed as closely as possible in some series of tests. Additional specimens were made and cured using time

schedules more easily accommodated in a laboratory in an attempt to develop a test method for evaluating different cements.

This article is limited in scope to the study of the variables associated with the differences in compressive strength obtained -with different

cements. It is recognized that other properties

such as reduced shrinkage, or better sulfate re- sistance, or manufacturing problems such as the

green strength, color, and time schedules are also of importance. The study and discussion of these

are, however, outside the scope of the present

investigation.

Although a number of variables were considered

in the present study, they were limited in scope

compared with those in commercial practice where

changes may be made in mix design, cement content, aggregate and aggregate gradation, admixtures, water-cement ratio as well as curing

schedule and temperature in order to achieve the

desired quality of the manufactured product or products.

2. IVIaterials

The Portland cements used for the series of tests reported in this section have previously been

described [20, 21, 22]. Some of the cements Avere not tested as Avill be indicated in the next subsection. The samples of cement had been stored

in air-tight containers approximately 10 years

before these present tests were made. Loss-onignition tests, made on the cements just prior

to the present study, indicated a close agreement

of values with those obtained in the origmal

analyses. A further verification of the cementsample identities was made by determining the

Na20 and K2O by means of a flame photometer

and comparing these values with those of the

original analyses.

A mixture of Ottawa silica sand, Gopher silica sand, and sihca flour was used in all mortars. The mix-proportion was 1 part of cement to 3.525

parts of silica by weight. A water-cement ratio of 0.5 by weight was used with all cements. The mix

proportions of the cements, sand, silica flour and

water are presented in table 8-1 for both the 9- cube and 6-cube batches. The particle-size

distribution of sand plus silica flour is presented

in table 8-2. Tests made by means of a Coulter

Table 8-1. Mix proportions for 9-cube and 6-cube batches of mortar

Materials 9-Cube 6- Cube

batch batch

20-30 Ottawa sand g-- 900 600 Graded Ottawa sand-.- g-- 870 580 Gopher #Osand g-- 240 160

Silica flour g^- 105 70 Cement g-- 600 400 Water ml-- 300 200

68
counter indicated that 93 percent of the silica flour was finer than 5^1, and 43 percent was

finer than 2^. Preliminary tests had indicated that mortars

made with these proportions were plastic, and

had percentage flow values on the standard 10-in

flow table of about 100 with 25 drops. It was

reported by some operators as being more sticky

and somewhat more difficult to trowel the speci- mens than the standard 1 :2.75 (cement to graded

Ottawa sand) mortars.

Table 8-2. Size distribution of sand plus silica flour mixture used for all mortars

Sieve Opening Percentage No. Microns passing

20 841 100 30 595 57.0

40 420 40.4

50 297 25. 4

70 210 18.9 100 149 12.2

140 105 5.7 200 74 5.4

3. Tests and Nomenclature

The cement-sand-water mortars were mixed, and

the 2-in cubes compacted in accordance with the

requirements of Federal Test Method Standard,

SS-C-158 [23]. After troweling, monel identification-tags were imbedded in each cube. Compressive-strength tests were made after steam curing

at both atmospheric pressure and 10 atm gage

pressure, as well as after moist curing at 23 ± 1.7 °C

for 28 days. The time, temperature, and curing

procedures, as well as the condition of the 8 sets

of specimens at the time of the compression test are summarized in table 8-3, and will also be

described more fully in this subsection. The time

at which specimens were removed from the molds

and placed in steam or autoclave are approximate,

as nearly 2}^ hr were required to make the speci- mens of each test group.

3.1. Series I, Curing Started at 5 Hr

Three batches of test specimens were made mth

each of the available cements.^ Additional dupli- cate batches were made with some cements as

^\^ll be discussed later. For the first series of tests "9-cube" batches were made using 161 cements.

Of these batches, 3 cubes from each cement were

stored at 23 °C, 95-100 percent RH for 28 days

and tested in compression when moist. These are

identified as WAGR in both tables and illustrations. Six of the cubes from each cement were

carefully removed from the molds at about 5 hr

after making.^

- Samples of some of the other cements had been used up in earlier tests or were not available in quantities sufficient for these series of tests.

3 Preliminary tests had indicated that removal from the molds prior to 5 hr resulted in excessive breakage of tlie relatively weak specimens. Specimens

from a few of the cements could not be removed without damage.

Three of these specimens were placed on racks

in a container and subjected to live steam at atmospheric pressure. The temperature, as indicated by a recording thermometer having the

sensing bulb near the center of the container, was

raised to 66 °C (150_°F) in 4 to 4)^ hr. This temperature was then maintained for 12 to 13 hi\ The

cubes were then removed and placed on shelves in the laboratory with 5 sides exposed to the laboratory air at 23 °C, 50 ±5 percent RH imtil tested

in compression at 28 days. These specimens are

identified as STGR, and the procedure used simulated to some extent the commercial practice of low-pressure-steam curing of specimens when stUl "green," i.e., not fuUy hardened.

The other 3 cubes from each batch of the fii'st series, removed from the molds at about 5 hr, were placed on racks in an autoclave and the

steam pressure raised to about 10 atm (actually

150 psi gage pressure) in 3 to dji hr. This included

the time required to vent the air from the autoclave. The steam pressm'e was maintained for approximately 11 hr. About 3 hr were required

for the autoclave to cool. The specimens were

then placed in a forced-draft oven at approximately 105 °C for 24 hr after which they were

placed in laboratory air at 23 °C and 50 percent

RH for 2 or 3 days and tested in compression.*

These specimens are identified at AUGR and the

procedure used simulated to some extent the

commercial practice of starting the autoclave

curing of the products when they are still "gieen."

* It was necessary to abrade adhering sand grains from the STGR and AUGR specimens with aluminum oxide cloth on a steel plate prior to the compressive-strength tests. Table 8-3. Summary of curing conditions, and condition at time of test of the different specimens

Identification Time in molds at 23 °C hr. Time to reach temp or pres hr. Temperature °C.

Pressure, atmospheres atm. Time at temp or pres hr. Time to cool do... Temp of drying °C_ Tune for drying days. Time at 100% RH do... Age at test do... Condition at test

STGR

5

66

1 12-13

1 23

27 '"'"28"' dry

Series 1 AUGR

5 3-3 1,^

10

113

105

1

dry

WAGR

24

23

1

wet

STMA

2-3

2 wet

Series 2 AUJIA

24

31/2

10

43

105

1

4 dry

WAMA

23

1

23

14

1428 dry

Series 3 WETS

24 24

!•'' 66

" 66

1 1 24 24

1 1 2312

2 14 wet dry

69
The time in the autoclave was, however, longer

than that used in commercial practice

Duplicate batches were made ^\dth some of the

cements in this series. Four different days were

required to make this series of cement mortars. Of 21 of the cements placed under test the first day, tests of seven of these cements were repeated on the second day, seven others on the third day,

and seven others on the fourth day. Six laboratory

personnel (plus other helpers) made specimens

each day they were fabricated. The duplicates were made to evaluate differences in time temperature-curing cycles of the different days as well

as possible other differences in the making of the

test specimens.

3.2. Series II, Curing Started After 24 Hr

A second series of mortars was made using the same cements. Both nine- and six-cube batches were made because of the limited supply of some

of the samples. The mortar proportions and preparation of the specimens were the same as in the

first series. The specimens were removed from the

molds at 22 to 24 hr. A third of the specimens

from each cement were cured at 100 percent K,H,

23 °C for two weeks, then placed in laboratory

air for two weeks and tested in compression without rewetting. These specimens are identified as WAMA in the various tables and illustrations. A

third of the specimens were placed in a container

and live steam admitted. The recording thermometer (with sensing h^Ah near the center of

the container) indicated that about )^ hr was

required to raise the temperature to 71 °C (160

°F). This temperature was maintained for about

7^2 hr, after which the steam was turned off. About 3 hr were required for the specimens (as

indicated by the recording thermometer) to come

to room temperature. The specimens were allowed

to remain in the container overnight (an additional

12 to 14 hr), then placed in water and tested in

compression at the age of about 50 hr. These

specimens, which were steam cured when more

mature but for a shorter period of time and slightly

higher temperatiue than the STGR specimens in

series I, are identified at STMA in tables and

illustrations. The other third of the specimens cured for 24

hr at normal temperatures were placed in an

autoclave and the pressure raised to 10 atni (after

the bleeding period) for about 3K hr. The temperature

and pressure were maintained for 3K hr, after which

the electric heaters were turned off. About 3 to 4

hr were required to cool the autoclave but the

specimens remained in the vessel overnight (about

12 to 14 hr), after which they were dried at 105

°C for 24 hr, then removed to the 23 °C, 50 percent RH room where they were tested in compression

after 2 more days. These specimens, autoclaved

after they were mature, are identified as AUMA

in both tables and illustrations. The specimens were made on four different

days. Duplicate tests were made on 21 of the

cements in the same manner as in the first series.

3.3. Series III, Normally Cured Specimens

The third series of mortars was made on 65 of

the Portland cements having sufficient quantities

of samples available. The batches were of the

six-cube size, and all specimens were cured in

steam at 150 °I (66 °C) for 24 hr after the first 24 hr in the moist room. Three of the specimens were then placed in water and cooled for a few

hours and tested in compression when still wet. These specimens are identified as WETS. The

other three specimens were allowed to dry in laboratory air at 23 °C, 50 percent RH for two

weeks and tested without rewetting. These speci- mens are identified as DRYS. The mortars in the

third series were made on three different days

and duplicate mortars were made with 10 of the

cements.

3.4. Other Notations and Comparisons

In addition to the use of WAGE, WAMA,

STGR, STMA, AUGR, AUMA, WETS, and

DRYS as indicated above to identify the different

curing conditions, reference will also be made to STOl, ST03, ST07, ST28, STlY, ST5Y, for compressive strength after moist curing of the

1:2.75 mortars at 1, 3, 7, 28 days, 1 year, and 5 years respectively as in the previous section.

The notations STlM and STlA, which are also used, refer to the 1 year moist-air cured and the

1 year laboratory-air cured specimens. (See page

2). Also used are ISET for initial time of set and FSET for final time of set of neat portland

cement pastes of normal consistency. Other

notations and abbreviations are consistent with

those used in previous sections in this series of

articles.^

4. Statistical Treatment

The statistical treatment of the compressive

strength data obtained was the same as that used

in previous sections of this series of articles. It was

described in detail in Part 1 section 1 [20]. Briefly

it consisted of determining which of the available

independent variables appeared to have a significant relation to the dependent variable, and

should be tried in the equations. Equations were

calculated by the least-squares methods to determine which of the variables and combinations of variables appeared to have a significant effect in

' Included among these notations etc. are the use of C3A, C3S, C2S, and CiW for the calculated potential compound composition of the cements, viz, tricalcium aluminate, tricalcium silicate, dicalcium silicate, and tetracalciuna aluminoferrite. Also used are Loss for loss-on-ignition, Insol for insoluble

residue, APF for air-permeability fineness and WAGN for fineness deter- mined by means of the Wagner turbidimeter. AE+NAE is used to designate

air-entraining plus nonair-entraining cements and NAE for the nonair- entraining cements. 70
improving the agreement of the actual values and

those calculated by the equation. As in previous

sections, the equations were computed for both

the AE+NAE and the NAE cements, for com- monly determined variables, and these together

with trace elements all of which had coef./s.d.

ratios ^ greater than one when used in the various

combinations. Equations were also calculated for the "odds" and "evens" in the array of cements.

Some of the limitations of the statistical treatment

and the interpretations of the results have been

discussed in previous sections.

No attemi)t was made to calculate equations

relating various independent variables to the

compressive strengths of the specimens "WETS"

and "DRYS" because of the limited number of

cements involved.

5. Results of Tests

5.1. Compressive Strength at 28 Days

Moist-Air-Cured Specimens (WAGR)

of

The frequency distributions of the different

types of cements -with respect to the compressivestrength values of the moist-air-cured specimens,

WAGR, are presented in table 8-4. There was

6 The statistical terms used in this section are consistent with those used in previous sections. For example, S.D. refers to the estimated standard

deviation calculated from the residuals of a fitted equation, or the estimated

standard deviation about the average. Also as, in previous sections, s.d. refers to the estimated standard deviation of a coefficient of an independent variable used in a fitted equation. The coef./s.d. is the ratio of the estimated coefficient

(of an independent variable used in an equation) to its estimated standard

deviation. " F" =Fisher's ratio of variances. As indicated in previous sections, a coef./s.d. ratio greater than 1 was considered to be of sufficient significance

to warrant further investigation. The one- and five-percent probability levels

refer to a=0.01 and o=0.05 as used in table 8-28.

considerable overlapping of the values of the

cements of the different types as classified, and a spread of values \\dthin each group. The frequency

distribution is also presented in figure 8-1 together

vdth the frequency distributions obtained with

these cements after other curing procedures.

Equations selected from those computed to determine the various independent variables

associated with the 28-day compressive strength

values for the moist-cured specimens of the

AE-fNAE cements are presented in table 8-5.

Commonly determined variables associated with

the compressive strength values are presented in

eq 1. The air contents of these mortars were not

3

to4

4 5 6 7 8 9 10 II 12 13 to to to to to to to to to to 5 6 7 8 9 10 II 12 13 14 COMPRESSIVE STRENGTH, PSI X lO"'

14to

15

15to

16

16to

17

17 to

IB

Figure 8-1. Frequency distribution curves for the strength of cements when the mortar cubes were tested in compression after the different curing conditions. STMA, steam cured at 71 °C for 7.5 hr after 24 hr at 23 °C, and tested wet. ST28, water cured 28 days (1:2.75 mortar): STGR, steam cured at 66 °C for 12 hr after 5 hr at 23 °C, and tested after air drying. STIY, water cured 1 year (1:2.75 mortar). WAGR,- moist air cured for 28 days and tested wet. WAMA, moist air cured for 14 days then air-dried for 14 days, and tested dry. AUMA, after 24 hr at 23 °C, the cubes were autoclaved at 10 atm for 4 hr, then oven dried, and tested dry. AUGR, after 5 hr at 23 °C, the cubes were autoclaved at 10 atm, then oven dried, and tested dry.)

71
Table 8-4. Frequency distribution of cements with respect to compressive strengths of 28 day moist-air-stored mortar

cubes iWAGR)

Compressive strength, psiX10-<i Typ6 C6ni6nt 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 Total

to to to to to to to to to to to

5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0

Number of cements

4 9 16 13 8 11 1 62 lA 1 1 1 2 1 21 6 II .__ 2 3 12 16 4 1 59 IIA 1 1 2 III 1 3 2 5 6 1 18 IIIA 1 1 IV, V 1 4 3 1 "i 'i" 13

Total 1 1 7 18 34 37 30 18 7 7 1 161

determined and it was necessary to use the air- content values of the 1 :4 (cement to sand) mortars

as an independent variable. The addition of Insol,

Cu, and Ba in eq 2 resulted in a highly significant

reduction in the S.D. value (see table 8-28)/

However, the equations calculated for the "odds"

and "evens" in the array of cements, eqs 2A and

2B, indicated that Insol and Loss each had

coef./s.d. ratios less than 1 in one of the smaller

groups of cements.*

The use of the air-permeabUity-fineness values

in place of Wagner fineness in eq 3 together with

the other independent variables, and the additional variable, Rb, resulted in an S.D. of a higher

value than was obtained in eq 2. In fact, the S.D.

in eq 3 was almost the same as for eq 1 where

only four independent variables were included.

Equations 4 through 6 present a similar series of relationships using the major oxides instead of the potential compounds. AI2O3 has a coef./s.d.

ratios less than 1 in eq 4 and is probably not significant. The ratio was somewhat greater than 2

in eq 6 where WAGN was used as an independent

variable. The coefficient for the insoluble residue

is also of questionable significance. The reduction

in variance resulting from the use of Cu and Ba

in eq 5 was highly significant. (See table 8-28.)

Equations calculated for the NAE cements are presented in table 8-6. The coef./s.d. ratio for Insol was greater than 2 in eqs 2, 3, 5, and 6. The coefiicients and the coef./s.d. ratios of the

independent variables were not greatly different

from those in the previous tab'e, 8-5, where the

air-entraining cements were included.

The estimated contributions of the various

independent variables calculated from the coefiicients of eq 2 of table 8-6 are presented in table 8-7 ^ together with the calculated ranges of such contributions. The ranges of the independent

'A tabulation of the reduction in variance, "F" values, for all equations compared is presented in table 8-28. Presented also are the critical values for "F" which must be exceeded for significance at the £i=one- and five-percent

levels for the number of degrees of freedom (D.F.) involved in each

comparison.

8 As has been indicated in previous sections, chance occurrence of two or more extreme values in one of the two groups may cause such anomalous

results. Another possible contributing factor was the assignment of zero to values for trace elements having less than the lowest reported value.

3 As in previous sections, these values must be added to the constant. Attention is called to the fact that the constant and coefficients must be

multiplied by 1000 to obtain values in terms of psi.

+

g

10

I GOa

J

03

<i

5160 00 r 5634 5182 (M 1 OS p

5556 . 1 to . 10 . 0 1 OS 1 »o 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1

10 o

10 ci

O CM

O "5

I

(O CD t--

10 TP

I

r

»0 (M

"J ^ O CO O CO

CO c4 10

CO Q 0 OC

to W O CI If5 CO O (M CO OS

CO O CO"rf CM CS .-H Tt* CO CO 00

I ^ 00

I 00 00

I ^ 00

£2 S OS S? --"^

oof- OSQO Q"^ OSCO

tn<^ lOi-HrH (MO t~- S

90 000 CM'-' CM CO 00s ^ OS 00^ TP IC -iJo (NO (MO CO^ O-H ICO -hO -ho IS i-i O 00 00' 00 00' 00 00 00" 00 00 oci

1 1^ I^J" I"' I f \^ \^ 1^

TP ^ OsO (Xst^ lO fl COM t-CO CO«? -^Jtic COCO 10 CI 000s OCO 1--CO T-if^ 0(M lOt- Oit- MM 00 00 t-H o 00 00 00 00 i-H o 00 00 00 00 o'o 00 00 00 0*0 00 00 IW 1^ 1-.^ I_ 1^ I-- 1^ 1^

COC3 OO'-* 00 iM OSiM rHO O -HO T-i O 22 00 00 00 00

00" 00 00 00 +^ +-

i-l o , , _ 00 0000

o— wo0000

00

+ 00

00o o 00

00+^

00

o o

xO OCO

OS O

CO lO 00 <M <M O 00

I

rHO

<M w

(M go

<N O 00

CO O 00 o o

o o

I ^

(M O 00

I ^

w o 00 00

iM O 00

T-H O 00

00^

CO CO

-H Tj* CM O

o'o

00

00

CO »C OS OS

OS CO OS CO O CO o 00 00

00

OS (M (M

I - I CO 00 CO CO o 00 00

00 00

OS CO OS CO 1—» 00 10 OS

OS »0 Tf* M o CO o

II II

C-1 O Tt* o O CO

-H CD O tJh" -H CO

I ^

M 05 <A «

0

ti ti ti ti ti

72
a s

1^ I -

00 CC 00 CD

I

OS lO

O lO

»0 CD

OO Ttl

»0 (M 00 o CM

0> (M CO M CD CO do I—I Oi lo

CD CO !> CO

O <31 O <M CO CM GO O Ol

i-H T-l TP O O i-H O

O .-I CD lO O CICO CX) 1-H CM p i-i CO o>

t— -rf* eo oi

OOi

CO (30

r-t COo

5 CI lO CM CO!M

f-< O --HO o >o

»C 00

OS CO

CJOM OO

o2 OOS (M

T-t o

CD SO cOd p o OO

1-H O o o OO

o o o o OO

OO

OO

OO

--I o eo CD

00 OS OS CJO O CO CO OS CO CN O

CI o

d d

eo

OS O C^ CM eo CO CO 00 o o

I ^

iC CI

eo CO

C) o

d d

OS ^ CD C)

C-1 to

C4 O do

OS Ifl Cl. CO CM CO CM

,—1 CD

CJ O C) O do o d

00 OS toS8

O OO

,—1 S3

oo

+

k'o O CIci CO

CD ^

CO o CI OS CO tOr-i d Tp o CO

I ^ +- I -

II II II II II II

a o^1

variables of these cements were assumed to be

the same as for all 199 cements previously described in sections 2 and 3 of this series. The in- crease in C3S and fineness was associated with an

increase in compressive strength; and an increase

in au' content of the 1 :4 (cement to sand) mortar,

Ba, Cu, and possibly also Loss and Insol, with

lower compressive strength values.

Somewhat different values may be obtained

by use of other equations in this table for NAE

cements, and also by use of equations presented

in table 8-5 for the AE+NAE cements. Other

tables of the "estimated contributions" wUl, for the sake of consistency, also be presented for the

NAE cements only. In all instances, an equation

having potential compounds and all other in- dependent variables having coef./s.d. ratios greater

than one will be used.

Table 8-7. Calculated contributions of independent variables

to compressive strength of mortar cubes (WAGR), moisl-air- cured for 28 days at 23 °C, and the calculated ranges of such contributions

Cal- culated Inde- Coefficients Calculated range of pendent Range of variable from eq (2) contribution contri- variable (percent) table 8-6 to WAGR bution to (XlO-3) WAGR

(XIO-^)

Const =+3. 609 C3S 20 to 65 +0. 0413 +0. 826 to +2. 685 1.859 WAGN__- •1200 to 3000 +0. 00180 +2. 160 to +5. 400 3.240

Air, 1:4 mortar. 1 to 21 +0. 1420 +0. 142 to -2. 982 2. 840 Loss -- 0.3 to 3.3 -0. 2000 -0. 060 to -0. 660 0. 600

Insol 0 to 1.0 -0.7850 0 to -0. 785 0.785 Cu 0 to 0. 05 -17.81 0 to -0. 890 0.890 Ba 0 to 0.

2

-3. 71 0 to -0. 742 0.742

*cmVg

5.2. Compressive Strength of Specimens

Moist-Cured for 2 Weeks Then Air-Dried for

2 Weeks, (WAMA)

The frequency distribution of the cements with

respect to compressive strength of specimens.

WAMA, cured for the first 14 days at 23 °C and

100 percent RH and then air-dried at 23 °C and

50 percent RH are presented in table 8-8. There was a fairly broad spread of results within each

of the types and considerable overlapping of the

values for the different types. (See also fig. 8-1.)

Equations relating the compressive-strength

values of the air-dried specimens to various

independent variables are presented in table 8-9

for the AE-I-NAE cements and in table 8-10

for the NAE cements alone. The use of commonly

determined variables in eq 1 of table 8-9 resulted

in a significant reduction of the S.D. value.

With additional variables, Insol, and SO3, and

the trace of elements, Ba, Cu, and SrO in eq 2, a

further significant reduction in the S.D. value was attained (see table 8-28) although the coefficients for Insol, SO3, Cu, and SrO were each

of questionable significance. The use of the air- permeability-fineness values in eq 3 together

73
Table 8-8. Frequency distribution of cements with respect to compressive strength of mortars, moist-cured I4 days, then air-dried

1 4-days (WAMA)

Compressive strength, psiXlO-'

J. tjClliclll/ 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 Total

to to to to to to to to to to to to

6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 Number of cements

I 1 6

2

5

9

38

1

17 10

1 19

1

6 11 4 64

7622

17

1 14

lA. 1 II.. 16 8 5 1 IIA _ ni 3 3

11

3 4 2 2 niA

IV, V 1 4 4 1 3

Total 2 1 17 25 34 34 17 21 8 4 2 2 167

Table 8-9. Coefficients for equations relating the 28 day compressive strength of mortars {moist-cured

Equation No. Note psiXlO-' Const C3A C3S CjAF CaO SiOz SO3

1 (')

(')

(2)

(>)

(1)

(')

(2)

(2)

(')

WAMA = +1.663

s.d. = (0. 786) WAMA = +2.133

s.d. = (0. 777) WAMA (odd) = +4. 488

s.d. = (1. 026) WAMA (even) = +1. 138

s.d. = (1.103) WAMA = +3.620

s.d. = (0. 747) WAMA = -2.713

s.d. = (3.217) WAMA = -3.444

s.d. = (3. 148) WAMA (odd) =+10.150

s.d. = (4. 146) WAMA (even) =-16.825

s.d. = (3.981) WAMA = -4.007

s.d. = (3. 343)

+0. 0961

(0. 0232)

+0. 0899

(0.0288) +0. 1068

(0. 0419)

+0. 0682

(0. 0376)

+0. 0405

(0. 0281)

+0. 0564

(0. 0102)

+0. 0548

(0. 0100)

*+0. 0138

(0. 0140) +0. 0841

(0. 0139)

+0. 0579

(0. 0106)

+0. 0589

(0. 0301)

+0. 0629

(0. 0305)

+0. 0492

(0.0383) •+0. 0278

(0. 0448)

+0. 0470

(0. 0319)

2 +0. 2461

(0. 1957) *+0. 2273

(0.2770)

+0. 2720

(0. 2614)

•+0. 1830

(0. 2198)

2A

2B

3.. -

4 +0. 2496

(0. 0500)

+0. 2633

(0. 0480) *+0. 0366

(0. 0668)

+0. 4584

(0. 0593)

+0. 2552

(0.0515)

-0.3393

(0.0487) -0. 3232

(0. 0517)

-0. 2545

(0. 0701) -0.3160

(0. 0642) -0.2342

(0. 0559)

5

5A

5B

6 -

1 146 cements; Avg=8.653X105 psi; S.D. =1.037X10' psi. 2 73 cements. *Coef./s.d. ratio less than 1. Table 8-10. Coefficients for equations relating the 28 day compressive strength of mortars {moist-cured

Equation No. Note psiXlO-' Const C3A CjS CAE CaO Si02 SO3

1 (>)

(1)

(=)

(>)

(')

(') m

{')

(')

WAMA =+1.948

s.d. = (0.852) WAMA =+2.691

s.d. = (0.838) WAMA (odd) =+3.393

s.d. = (1.187) WAMA (even) =+1.935

s.d. = (1.087) WAMA =+4.202

s.d. = (0.781) WAMA =-2.426

s.d. = (3.273) WAMA =-3.084

s.d. = (3.233) WAMA (odd) = -0. 309

s.d. = (4.774) WAMA (even) = -5. 577

s.d. = (4.863) WAMA =-3.011

s.d. = (3.375)

+0. 0919

(0. 0240)

+0. 0823

(0. 0293)

+0. 0497

(0. 0460)

+0. 1298

(0. 0358)

+0. 0524

(0. 0268)

+0. 0594

(0. 0105)

+0. 0569

(0. 0102)

+0. 0597

(0. 0150)

+0. 0414

(0. 0132)

+0. 0560

(0. 0107)

+0. 0570

(0. 0312)

+0. 0509

(0. 0314)

+0. 0789

(0.0473)

* +0.0204

(0. 0405)

+0. 0431

(0. 0316)

2 +0. 4116

(0. 2095)

+0. 5015

(0. 3243 •-0. 0771)

(0. 2680)

2A

2B

3

4 _ +0. 2549

(0.0505)

+0. 2671

(0. 0486)

+0. 2284

(0. 0723)

+0. 2841

(0. 0710)

+0. 2511

(0. 0513)

-0. 3474

(0.0499)

-0. 3325

(0.0535) -0. 3309

(0. 0822)

-0. 3215

(0. 0675)

-0. 2445

(0. 0567)

5

5A

5B

6

1 137 cements; Avg=8.699X10' psi; S.D. =1.028X10' psi. 2 69 cements. ' 68 cements. *Coef./s.d. ratio less than 1.

74
with the other variables of eq 2 resulted in a

higher value for the S.D., and the SO3 and SrO

had coef./s.d. ratios less than 1. In this case the

S.D. for eq 3 was even higher than that for eq 1. A similar series of relationships calculated

using the major oxides instead of the potential

compounds are presented in eqs 4, 5, and 6. The SO3 did not have a coef./s.d. ratio greater

than 1 and was not included. In the equations for the "odds" and "evens"

in the array of cements, there were instances

where the coef./s.d. ratios for C3S, C4AF, CaO,

Na20, SO3, Loss, Insol, Cu, and SrO were less than 1 in the smaller groups. The Loss-on-ignition

was more highly significant in eqs 3 and 6 where

APF was used than in eqs 2 and 5 where the

Wagner fineness was used.

Comments relative to the relationship indicated

in table 8-9 for AE+NAE cements, are in general,

also applicable to the relationships in table 8-10

for the NAE cements alone. The estimated contributions of the various in- dependent variables to the compressive strength

of the air-dried nonsteamed specimens were cal- culated from the coefficients of eq 2 of table 8-10

and are presented in table 8-11 together with the

calculated ranges of these contributions. Increased

values of C3A, C3S, fineness, and possibly also

2 weeks then air-dried 2 weeks) of AE-\-NAE cements to various independent variables {WAMA)

NaiO WAGN APF Loss Insol Air 1:4 mortar Cu SrO S.D.

-0. 7758

(0. 3372)

-0. 6750

(0. 3508) -1. 2135

(0. 4597)

• -0.3653

(0. 4957)

-0. 6378

(0. 3697)

-0. 8535

(0. 3362)

-0. 7008

(0. 3436)

-1. 1056

(0. 4471) *-0.3971

(0. 4411) -0.6883

(0. 3658)

+0. 00208

(0. 00025)

+0. 00190

(0. 00027) +0. 00186

(0. 00033)

+0. 00184

(0. 00045)

+0. 00210

(0. 00023)

+0. 00201

(0. 00022)

+0. 00186

(0. 00028)

+0. 00225

(0. 00030)

+0. 000827

(0. 000151)

+0. 000934

(0. 000123)

-0. 2718

(0. 1090) -0. 2962

(0. 1154)

-0. 1961

(0. 1568)

-0. 2152

(0. 1578)

-0. 5397

(0. 1222)

-0. 2227

(0. 1119)

-0. 2141

(0. 1107)

-0. 2393

(0. 1415) •-0. 0044

(0. 1478)

-0. 4597

(0. 1247)

-0. 6207

(0. 4212)

-2. 4421

(0. 6517)

•+0. 2727

(0. 5253)

-0. 5545

(0. 4436)

-0. 5788

(0. 4124) -0. 6513

(0. 4032)

—2. 2409

(O] 5898)

*+0. 1726

(0. 4771) -0. 7251

(0. 4285)

-0. 0686

(0.0159) -0. 0699

(0. 0161)

-0. 0402

(0. 0200)

-0. 0960

(0. 0228)

-0. 0768

(0. 0168)

-0. 0625

(0.0158)

-0. 0626

(0. 0151)

-0. 0426

(0. 0195)

-0. 0786

(0. 0188)

-0. 0709

(0. 0161)

-4. 734

(1. 789)

-9. 891

(4. 238) -4. 471

(1.974)

-5. 115

(1. 889)

-4. 773

(1. 736) -9.582

(3.973)

-4. 805

(1. 747) -4.917

(1.846)

-12.88

(6.77)

-4. 93

(9.81)

-18.42

(8. 69)

-14. 61

(7.17)

-14.93

(6.41) *-6.92

(8.93) -24. 19

(7. 82)

-16. 00

(6.82)

-1. 101

(0. 705)

-1. 747

(0.920)

-0. 847

(0. 987)

* -0.736

(0. 742)

-1. 059

(0.671)

-1. 567

(0. 877) •-0. 657

(0. 850) -0.935

(0. 714)

0. 6719

0.6441

0. 5937

0. 5987

0. 6786

0. 6666

0. 6362

0. 5851

0. 5515

0. 6762

2 weeks then air-dried 2 weeks) of NAE cements to various independent variables (WAMA)

NazO WAGN APF Loss Insol Air 1:4 mortar Ba Cu SrO

-0. 5250

(0. 3645) +0. 00205(0. 00026) -0. 3843

(0. 3801)

-1-0. 00174

(0. 00028) -0. 6636

(0. 5040)

-i-0. 00128

(0. 00037)

-0. 6996

(0. 5752)

-1-0. 00291

(0. 00042) *-0. 3871

(0.3883) -0. 6399

(0. 3575)

4-0. 00207

(0. 00024)

-0. 6369

(0. 3673) +0. 00197

(0. 00023)

-0. 6741

(0. 4986) +0. 00156

(0. 00032)

• -0.4536

(0. 5529)

-1-0. 00255

(0. 00031) -0. 4332

(0.3854)

4-0. 000905

(0. 000129)

4-0. 000936

(0. 000123)

-0. 2639

(0. 1136)

-0. 3200

(0. 1176)

-0. 3410

(0. 1531) •-0. 0777

(0. 1887)

-0. 5038

(0. 1213)

-0. 2080

(0. 1156)

-0. 2169

(0. 1143) -0. 2623

(0. 1507)

-0. 0417

(0. 1848)

-0. 4528

(0. 1253)

-0. 8495

(0. 4576)

-0. 9731

(0. 6344) -1.0354

(0. 6393)

-0. 9354

(0. 4774)

-0. 8222

(0. 4524)

-0. 8835

(0. 4403)

-1. 1903

(0. 6120) *-0. 5815

(0. 6211)

-1.0768

(0. 4585)

-0. 1230

(0. 0351)

-0. 1407

(0. 0371)

-0. 1354

(0. 0557)

-0. 1181

(0. 4049) -0. 1518

(0. 0355) -0. 1217

(0. 0342)

-0. 1065

(0. 0333)

-0. 1094

(0. 0524)

-0. 1109

(0. 0402) -0. 1435

(0. 0350)

-4. 772

(1. 798)

-14.971

(6. 676)

-4. 956

(1.809)

-4. 426

(1. 857)

-4. 679

(1. 776)

-11.227

(6. 282) -5.818

(1.914)

-4. 606

(1. 857)

-9.37

(6.99)

-26. 27

(11. 03)

*4-6. 74

(8.89)

-12. 52

(7. 14)

-13.45

(6.57)

-26. 77

(10.23)

•4-0.40

(8. 38) -13.86

(6. 86)

-1. 325

(0. 735) *-0. 586

(1.121) -2. 152

(0.875) -0.896

(0. 758)

-1. 190

(0. 709) •-0.829

(1.095) -1.630

(0. 872) -1.143

(0. 740)

75
C4AF and SO3 appeared associated with higher

compressive-strength values. Increased values of Loss, (air, 1:4 mortar), Ba, and possibly Na20,

Insol, Cu, and SrO appeared associated with lower

compressive-strength values.

Table 8-11. Calculated contributions of independent vari- ables to compressive strength of mortars (WAMA), moistair-cured for 14 days then air-dried I4 days at 23° C, and

the calculated ranges of such contributions

CalcuInde- Coefficient lated pendent Range of variable from eq (2) Calculated contri- range of variable (percent) table 8-10 bution to WAMA contribution to WAMA

(XlO-3)

Const. =+2. 691 C3A 1 to 15 +0. 0823 -1-0. 082 to +1. 234 1. 152 C3S 20 to 65 +0. 0569 -f-1. 138 to -t-3. 698 2.660 C4AF**.__ 1 to 16 +0. 0509 +0. 051 to -1-0. 814 0. 763 SO3" 1. 2 to 3. 0 +0. 4166 +0. 500 to -1-1. 250 0.750 NazO** 0 to 0.

-0. 3843 0 to -0. 269 0.269 WAGN.._ *1200 to 3000 +0. 00174 4-2. 088 to -t-5. 220 3. 132 Loss 0. 3 to 3.

-0. 3200 -0.096 to -1.056 0. 960 Insol** 0 to 1.0 -0. 8495 0 to -0.850 0. 850

Air, 1:4 mortar_._ 1 to 21 -0. 1407 -0. 141 to -2.955 2.814 Ba 0 to 0.

-4. 772 0 to -0.954 0. 954 Cu** 0 to 0. 05 -9. 37 0 to -0. 468 0. 468 SrO** 0 to 0.

-1.325 0 to -0.530 0. 530

*cm2/g.

**Coefficient of doubtful sigiriflcance as coef./s.d. was less than 2.

5.3. Compressive Strength of Mortars Cured

With Low-Pressure Steam After 5 Hr Moist

Curing and Later Dried in Laboratory Air

(STGR)

The frequency distributions of the cements with

respect to compressive strengths of the mortars,

STGR, steam cured at 66° C for 12 hr after about

5 hr in the fog room are presented in table 8-12.

The specimens were air dried for 27 days after the steam-curing, prior to the compressive-strength

tests. There was a fairly broad distribution of values within each of the types as classified, and

an overlapping of the values for the different

types of cement. (See also fig. 8-1.)

Selected equations relating various independent

variables to the compressive-strength values are presented in table 8-13 for the AE+NAE cements

and in table 8-14 for the NAE cements. The re- Table 8-12. Frequency distribution of cements with respect

to compressive strength of mortars, steam-cured after 6 hrs, then air-dried (STGR)

Compressive strength, psiXlO-^

Type 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.6 9.0 9.5 cement to to to to to to to to to to to to Total

4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0

Number of cements

I 1 1 4 17 12 12 7 6 2 62 lA 1 1 4 0 II i 5 17 17 10 6 1 69 IIA 1 1 o III ""i 1 2 1 2 4 3 4 18 IIIA 1 1 rv, v.... 1 3 4 2 3 13

Total.

3 5 15 41 32 24 15 10 5 4 3 4 161

s

s

a,S

«5o

to TP O CD Id CO"^ ^d cod dd .-id

I ^ I ^ I ^ I ^

o6»o coi^ ect~- in" J + I

•-Id CO d d d 1-H

d

1^ i- I- I1

I

I

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d d d d

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00 o o

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d d

TP CD

TP Oi o o dd

il II II II II II II II II

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II II II II II II II II

o cc

o o o o 0.0.0.0.0.0. E-i'a E-i'd E-i'd E-i'd H'd H'O H'O h'O E-i'o E-''0 W ui OJot Mui COco CQw f/a« c/3to CC!co

76
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CO tr- io .-H

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N CO COTh Tt< 00 O (M Q ^ O o o o o O O O O o o o o

00

»0 CO

C-i o o oo

o o OO OO

o o

do'

o OO

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e-1 o

o o o o OO o o

COc?

CO CO

£3 o Soo o is

00 (MCO

01 CO

CO Cft CO

CO Tf o C-) 00 CO o o do d d d d

CO (M O T-i COCO o o

O CO

!M 00

OSV CO Oleic 00 O CO O O o o o o dd

CO o CO a> I lo o

d d

I ^

rf o Tji O d d d d

CO oi CO

CO CO as w CO o o o

o o d d

I - I -

CO o dd

CO iC CD iC

CD GO lO CO O CO O

O O O O

CO O CO o dd dd

t-oo

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d d dd

OO

d d

o o

d d

o o dd

oodd

I- OS S3

CO OO OO.-H CD

00 iC lO C-1 O o

(M iC f— OS S3

OO o o dd

<N »2 OS CO

go CO O iC M d (NO 1^OS TlH CM !>.

t-i'a

P3 PiO .

d d d CO

« P3 O . O

«3 ui CO w

M ct3 CO ^ dco

t-i^ ' »-l ^ ^ ' T-H w

I

I I

I

« tf Ph O O . O o

Eh-o E-iTJ E-i-q E^xj

lationships with commonly determined variables are presented in eqs 1 and 4 of table 8-13. SO3

had a coef./s.d. ratio greater than one in eqs 1, 2, and 3, where the potential compounds were in- cluded but not with the variables in eqs 4, 5, and

6 where the oxides were used. The opposite was

found for Insol. The addition of the 3 trace elements, Ba, Cu, and P, in eqs 2 and 5 resulted

in significant reductions in the S.D. values (see

table 8-28). The use of the APF values in eqs

3 and 6 resulted in higher values for the S.D.

than were obtained in eqs 2 and 5. In eq 3 the

coef./s.d. ratio for C3A was less than one and the

coefficient for Loss was of somewhat greater significance than when the Wagner fineness values were used. The relationship between the fineness

values determined by the two methods and other

variables such as C3A, SO3, and loss on ignition

have previously been discussed in section 7 of this

series. Equations calculated for the "odds" and "even"

(eqs 2A, 2B, 5A, and 5B) indicated instances where

Loss, Insol, and Cu ha<i coef./s.d. ratios less than

one and in eq 2A the sign of the coefficient for Cu was positive instead of negative as in eq 2. The equations for the NAE cements presented

in table 8-14 present somewhat the same trend

as in table 8-13. There were, however, also in- stances where the SO3, K2O and (air, 1 :4 mortar)

had coef./s.d. ratios less than 1 in the equations

for the "odds" and "evens."

The estimated contributions of the independent

variables to the compressive strength of the steamcured specimens were calculated from the coeffi- cients of eq 2 of table 8-14 and are presented in

table 8-15 together with the calculated ranges of these contributions. Increases in C3A, C3S, SO3,

K2O, and fineness were associated with an increase

in the strength values, and increases in Loss, air content, Ba, P, and possibly Cu, associated with

the lower compressive strength values. Differences

in C3S, fineness, and air content had the greatest

effect.

Table 8-15. Calculated contributions of independent vari- ables to compressive strength of mortar cubes, steam-cured

after 5 hrs, then air-dried, and the calculated ranges of such

contributions (STGR)

Calculated Inde- Range of variable Coefficient Calculated range of pendent (percent) from eq (2) contribution to contri- variable table 8-14 STGR (XlO-3) bution

to STGR

(XlO-3)

Const. = -2. 094 C3A 1 to 15 +0. 0475 +0. 048 to +0. 712 0. 664 C3S 20 to 65 +0. 0853 +1. 706 to +5. 544 3.838 SO3 1. 2 to 3.

0

+0. 4949 +0. 594 to +1.485 0. 891 K2O 0 to 1.

1

+0. 5892 0 to +0. 648 0.648 WAGN.... *1200 to 3000 +0. 00223 +2. 676 to +6. 090 4. 014 Loss 0. 3 to 3.

3

-0.3111 -0.093 to -1.027 0. 934

Air, 1;4 1 to 21 -0. 0967 -0. 097 to -2. 031 1.916 mortar. Ba ___ 1 to 0.

2

-5. 64 0 to -1. 128 1. 128 Cu»* 0 to 0. 05 -6. 98 0 to -0. 349 0. 349 P 0 to 0.

5

-1.46 0 to -0. 730 0.730

* cm2/g.

** Coefficient of doubtful significance as coef./s.d. ratio was less than

276-694 0-681—6 77
5.4. Compressive Strength of Specimens Cured

With Low-Pressure Steam After 24 Hr,

Tested Wet (STMA)

The frequency distributions of the different

types of cements with respect to the compressive

strength of specimens STMA, steam-cured for l]/2

hr at 71° C after an initial 22 to 24 hr at normal

temperature are presented in table 8-16. The spec- imens were tested while moist after cooling to laboratory temperature. There was a considerable

range of values for each of the types and considerable overlapping of the values for the differ- ent types. The type III cements generally had the

higher values, and the types IV and V the lower

values (see also fig. 8-1).

Selected equations relating the compressive

strength values obtained with the different ce- ments to various independent variables are pre- sented in table 8-17 for the AE+NAE cements,

and the table 8-18 for the NAE cements. The

use of commonly determined variables as in eqs 1 and 4 of table 8-17, each resulted in a significant

reduction in the S.D. value (see table 8-28). The

addition of 4 additional variables MgO, Ba, Cu,

and Li, in eq 2 resulted in a slightly lower S.D.

value but the reduction was significant only at the 5 percent probability level. MgO and Li of the added variables in eq 2 were of doubtful significance. A similar comparison cannot be made

for eqs 4 and 5. However, there was only a slight

reduction in the S.D. value. AI2O3 had a coef./s.d.

ratio less than one in eq 4, but was probably

significant in eq 5.

Table 8-16. Frequency distribution of cements with respect

to compressive strength of mortars, steam-cured after 24

hr and tested when wet {STMA)

Compressive strength, psiXlO-3

2.0 2.5 .0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 Type cement to to to to to to to to to to to Total

2.5 3.0 3.5 4.0 4 5 5.0 5.5 6.0 6.5 7.0 7.5

Number of cements

I 1 7 18 18 12 5 2 63 lA 4 2 1 7 II

'2

15 23 17 4 61 IIA 1 1 2 III - i" 2 2 2 6 3 1 17 IIIA 1 1 IV, V 1 4 5 3 1 14 Total 1 7 32 47 38 18 7 6 3 1 165

Equations 2A, 2B, 5A, and 5B calculated for the "odds" and "evens" in the array of cements

indicated that there were instances where the

MgO, SO3, Cu, and Li had coef./s.d. ratios less than 1 in one or both of the smaller groups.

The use of the air-permeability-fineness values

in eqs 3 and 6 instead of the turbidimeter fineness

values in eqs 2 and 5 resulted in S.D. values which

were higher. Here again, the S.D. was higher than

for eq 1.

78

The relationship of the "STMA"compresssive

strength values of the NAE cements to various , independent variables are presented in table 8-18.

; The coefficients differ only slightly from those ; presented in the previous table where the AE i cements were included. Although some of the j coefficients were not highly significant, there was

no instance where the coef./s.d. ratios of the ; variables in the equations for the "odds" and ; "evens" (eqs 2.A., 2B, 5A, and 5B) were less than 1. Using the independent variables and their

'

coefficients in eq 2 of table 8-18, and the ranges of

these variables, values were calculated for their

J contributions to the STMA compressive-strength ; values. These calculated values are presented in j table 8-19 together with the calculated ranges

'

of these values. Increased values for C3S, C3A, i SO3, K2O, fineness, and possibly Li were associated

with higher strength values. Increased values for, j Loss (air, 1:4 mortar), and possibly Ba, Cu, and ! MgO, were associated with lower compressive j strength values. Of these variables, differences in C3S and fineness appear to have the greatest i effect.

5.5. Compressive Strength of Mortars Cured

With High- Pressure Steam After 5 Hr

Moist Storage (AUGR)

The frequency distribution of the compressivestrength values of mortars made of the different

cements and autoclaved after about 5 hrs (AUGR),

is presented in table 8-20 (after the autoclave

treatment, the mortar specimens were oven dried,

then stored for 2 days in laboratory air before the

compression tests). There was a considerable i spread of values for each of the types of cement

' and an overlapping of the cements of the different

types. As mentioned above, these specimens

attained the highest average strength level of all those tested. (See also fig. 8-1.)

Selected equations indicating the relationship^ of various independent variables to the compressive

strength of the autoclaved mortars are presented

in table 8-21 for the AE+NAE cements, and in table 8-22 for the NAE cements. The relationship

to commonly determined variables are presented

in eqs 1 and 4. Equations 2 and 5, table 8-21,

show the effect of the trace elements found to have | coef./s.d. ratios greater than 1. The reductions in ; the S.D. values were, in both instances, highly

significant. (See table 8-28.) In eq 3, where APF ; was used instead of WAGN, the S.D. is higher < than in eq 1. \ There were instances in the equations for the ; "odds" and "evens" in the array of cements = where SO3, Si02, and V had coef./s.d. ratios less

I than 1. The coefficients for SiOj and V were

probably not significant with the larger group,

j A similar set of equations is presented in table ' 8-22 for the NAE cements alone. Again, the use S of the 5 trace elements Ba, Cu, Li, Cr, and V in ,'

1
p 0.4267 0.4128 0.3981 0.

4205

0.

4357

0.

4222

0.4115 0.4101 0.

4129

0.

4312

; S§ 2S I

i 22 ^2 $2 2d :

; +^ 7~- +- :

! si sE

i S2 S2 $d 2d

; +- +- 7- +-

5

; Sf if ss :

; 2S -re ss :

; 1 J 1 1

:

: si SS 5i

i 2S 2S ?3£ SS

: 1 1 1 1

: ilslss ii ;

1 c-irt cm"^ o^- ;

; 1 ^ 1 ^ 1 ^ 1 - ;

i ll il ii il

1 7^

Air

1:4

mortar mm it il il ilili

c) o 2- ^ lifilo oo oo

Loss ililil il il if il il llil

oo oo oo oo oo oo oo oo oo oo

o

< |1. °S 2o o

APF i

I*'

o ; Ii

+

o

Os lliiliiilgl 1

; fS °S =£ °£ i il

ii ililil il i! if ililil

oo =e °s °s °s. °s °s OS. °s.

§ ilililil ililil illl il

°s °e °s °s °s °s °s °s °°

»

1 if II if ll il

; <=S °S °S °S °s

o i i! il il il il

; OS =S °£ OS oo

CaO

. il il il if il

oo oo oo oo oo

o if il i oo oo o

1 il il i

3 il ilili ill i

1

X1

ii 5lsg 38S 5i sg 111111,1,1 7° 7S -^S 7° 2£i 2i 2i

II II II II II II II II II II II II II II II II II II II II

1 1 1 1

^•0 ^H-a fH-d H-d &^T3 H-d t^-d t^-d H-d Ens mm Mm com Mm Mm Mm Mm Mm Mm Mm

Note

Equation

J CO 3 g

q

oi 1

o

2o

i

o i

o

0.4321 0.

4270

0.4133 0.

4377

0.3888 0.4281

3

+26.

97

(11.70) +23.

79

(17.84) +27.

63

(18.

08)

+25.

25

(12.

20)

+30.

56

(11.

66)

+27.

6S

(17.

92)

+31.70 (17.

90)

+26.

54

(12.

10)

3Q

-10.31 (4.

67)

-13.12 (6.

90)

-10.89 (V.

49)

-11.

42

(4.88)

-14,29

(4.48)

-15.

72

(6.

62)

-17.

37

(7.39)

-n.

11

(4.

95)

«

cs

-3.

021

(1.

159)

—2

508

(1.877) -2.

872

(1.

696)

-2.

800

(1.

218)

-3.

304

(1.

157)

-2.

958

(1.892)

-3.

173

(1.

678)

-2.

875

(1.214)

Air

1:4

mortar

-0.

0861

(0.

0217)

-0.

0951

(CI

02.'18>

-0.

1405

(0.

0146)

-0.

0666

(0.

0300)

-0.

1117

(0.

0248)

-0.0780 (0.

0218)

-0.

0814

(0.

0238)

-0.

1303

(0.

0406)

-0.

0444

(0.

0301)

-0

1092 1

o

iJ -0.

3763

(0.

0727)

-0.

3954

(U.

U7U3)

-0.4151

(U.

U94b)

-0.

3057

(0.

1242)

-0.

6535

(0.

0749)

-0.

1839

(0.

0849)

-0.

2974

(0.

0748)

-0.

2824

(0.

1113)

-0.

3031

(0.

1187)

-0.

4957

(0.

0873)

o

&

+0.

00177

(0.

00019)

+0.

00175

(0.

00019)

+0.

00163

(0.

00030)

+0.

00190

(0.

UUUZ7)

+0.

00180

(0.

00019)

+0.

00178

(0.

00019)

+0.

00159

(0.

00030)

+0.

00199

(0.

00027)

1

+0.

00084

(0.

00010)

+0.

00085

o

-0.

0524

(0.

0340)

-0.

0835

(0.

0516)

-0.

0947 (0

0497)

-0.

0389

(0.

0354)

+0.

1726

(0.

0518)

+0.

1093

(0.

0558)

il il il ii if il il !l il il

oo oo oo oo oo oo o^ oo oo oo

II ii il ii il ll il il ll il

oo oo oo oo oo oo og oo oo oo

-0.

1095

(0.

0876)

-0.

2353

(0.

0770)

-0.

2423

(0.

1210)

-0.

1809

(0.

1074)

-0.

2547

(0.

0868)

o.M

-0.3522 (0.

0801)

-0.

458

(0.0675)

-0.

4449

(0.

0968)

-0.

4485

(0.

1001)

-0.

3875

(0.

0813)

+0.

4979

(0.

0500)

+0.

4048

(0.

0348)

+0.

4280

(0.

0508)

+0.

3483

(0.0554)

+0.

4605

(0.

0539)

+0.

0599

(0.

0143)

+0.

0512

(0.

0145)

+0.

0493

(0.

0260)

+0.

0642

(0.

0181)

+0.

0230

(0.

0143)

+0.

0748

,

(0.

0063)

+0.

0749

+0.

0758

(0.

0088)

+0.

0666

(0.

0101)

+0.

0751

(0.

0067)

=

-3.398.

=

(0.

415)

=

-3.092

=

(0.

422)

—

9

Q1

1

—

—

^.

oil

=

(U.

IVZ)

)

=

-3.458

=

(0.

536)

=

-2.030

=

(0.

389)

=

-23.

49

=

(4.

66)

=

-13.

77

=

(2.97)

=

-14.

73

=

(4.

63)

)

=-11.26

=

(4.

17)

=

-18.

66

=

(4.93)

STMA

s.d.

STMA

s.d.

STMA

(odd)

s.d.

STMA

(even

s.d.

STMA

s.d.

STMA

s.d.

STMA

s.d.

STMA

(odd)

s.d.

STMA

(even

s.d.

STMA

s.d.

1

z £ ££££££

Equation

J J J s s 79
Table 8-19. Calculated contributions of independent vari- ables to the compressive strength of mortar cubes, steam- cured after 24 hrs and tested when in a moist condition,

(STMA) and the calculated ranges of such contributions

CalcuT J

illu6- Range of variable ooenicient pendent (percent) from eQ (2) 1-infinn UULlUll trt CITIVT A LU 0 1 lYiii. contribu ~ variable toHla ft—1R tion to STMA

VyUiiOt* — —0. \JtJ£i U3& 20 to 65 _I_Q 0749 4-1 4Qft trt -\-A RfiR 3. 370 U3A 1 to 15 1 n r\r-tn -pU. UDLZ n-u. uoi n~u. /do 0. 717 bU3 1.2 to 3.0 -f-u. ozou 0 950 KiiO 0 to 1.1 +0. 6548 0 to +0. 720 0. 720 MgO** 0 to 5.0 -0. 0524 0 to -0. 262 0. 262 WAGN..._ 1200 to 3000 +0. 00175 +2. 100 to +5. 250 3. 150 Loss 0.3 to 3.3 -0. 3954 -0.119 to -1.305 1.186 Air, 1:4 1 to 21 -0. 0951 -0.095 to -1.997 1.902 mortar. Ba 0 to 0.2 -3. 021 0 to -0. 604 0. 604 Cu 0 to 0.05 -10.31 0 to -0.516 0.516 Li 0 to 0.02 +26. 97 0 to +0. 539 0.539

*cm2/g. ••CoefHcient of doubtful significance as coef./s.d. ratio was less than 2.

Table 8-20. Frequency distribution of cements with respect

to compressive strength of mortars, autoclaved after 5 hr, and tested after drying (A UGR)

Type cement

Compressive strength, psiXlO-'

Total

9.0

to 10.0

10.0

to 11.0

11.0

to 12.0

12.0

to 13.0

13.0

to 14.0

14.0

to 15.0

15.0

to 16.0

16.0

to 17.0

17.0

to 18.0

Number of cements

IlA 1

1

1 4

17

184

14

1

28 11 659

218

1 11

IIIIA in

22

12

13

ii '3'4

'4' "3'

IIIA

IV, V

Total

3'

2 1 15 38 67 29 10 4 3 159

eqs 2 and 5 resulted in significantly lower S.D.

values. In the equations for the "odds" and "evens' there were instances where Ba, Si02, and V had

coef./s.d. ratios less than 1. The coefficients for Si02 and V were probably not significant with the

larger group of cements in eqs 2 and 5. The estimated contributions of the various in- dependent variables to the compressive strength

of the autoclaved mortars were calculated from

the variables and their coefficients in eq 2 of table

8-22 and are presented in table 8-23 together w4th

the calculated ranges of these contributions. It appears that increases in C3A, C3S, C2S, SO3,

fineness, Li, and Cr are associated with higher

compressive strength values. It also appears that

increases in (air, 1:4 mortar), Na20, Ba, Cu, and

possibly V, are associated with lower compressive

strength values. Of these variables, variations in

C3S, C2S, fineness, and the air content of the 1 :4 mortar appear to have the greatest effect.

t3

s

-sS

S

o

1 GOH

n

<DCO CO CO

+-' +"-'

g2 " ^ CO (MO

CO 00 iM (M

So 1-Hr- o

r-^ M (NO

CO .-H (N w

I ^ I -

CO 22 CDfO

I ^

O o «o

OS t—I 01 <o

CO CO o 00 iM

00 CO

, ^ I — CD

IC"* .—I 00 0>.—I t-i IC

CO'-' "rf< i-H (M (M Tji T-i

+ + +

CO^ TP >-i COi-H co^

I I ^ I I

CO o Tt* CI rCO CO CD CO

Oi CO SS

I

00 d OS

CO Oi 10 OS

i-H 1—I O C-1 .-HO r-l O

o' o 00

MO CO

»o 00 ^ g

J!^ o 00

H OS CD CO o o

I 00

00

I

00 00 OS O >—I 00 (M

I-H O 00 ^ o 00

oco

CO o o

o o oo+

CO O (MO O O

«o OS

(M O

O O

o so

o o

<M (MO

.-H CO oo-^

CO O <M O SO 00 o 00 00

.-H O o o 00

00

O CO

(M* O

(=>»C (M COOS "2 ih- OlOs cDoo CO'-H osr-- 5co os-'j' colo ocoOC O ^ CO OS OS c O <N O iM' O C<1 o

1.^ I"" I (NO (MO (M'O iMO

o o o o

OS CO O CO COoc=> 1-1 o

-M

00 (M 00

Tl< CO O CO O (M

(M 00

00 CO 01(M TfCO COCO 00c 00 00 ^"o 00

+ +^

2?2 100 -^00

c^'Ti t^'^ "-"^ O — CDOS

I-H O i-iO 00

?2-o<=> 00 o<o + +^

t>. o !>. CO

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t).^ ti'd ^-a 2'° 5'' <^ <^ ^"^ ^" ^"i ^ =

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fOO-l o * 00

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•-I o •-' o

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CO ^d o o 00

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t-- o CO 2; CO o 00

.-c O o o

do"

O lO

CO 1-H

f-H O 00

do*

OS-* 7'

OS <M W

CO (M

(M T-l OS O

O ^ T-l CO

CO •*

CO O CO Tt* to w o rOS CO 10 OS »0 *

t— N CO lO OS 00 *T-J CDO iO tM CO O -^Ji Tfl 10 OS IM O (N OS CO do d d

d

i>. 10

00

(M (M O CO

cot- tHIM lOoO 1-Ht 00 1>- O 10 coos OS*

Tt< r-~ coco OS CO * t o<M oscg oc^i oc

CO CO o *

CD (M O CO 00 d

( lO r-l OS OD »0 00 »0 pSiO OOC-l COi—1 t-HTP coco

r- CD T-H to 00s CN 00 to CD 00 1—( O ' O 1—I O (MO dd do dd dd dd +^ +- +^ +^ +^

i^t~- Oio osr-- ^cD osw •* (30 COW r- CD* 2! 00 10»0 1-HiO lOCO 000 Oio MO coo coo CM o coo dd dd dd dd od ^v..

OS 1-H CO CO i-HO * OS 00 CD CO

10 CM OOCO O ^ O 1-t O i-i o

CD i-< 00 <M

00 CO ^ O 00 00 00 00 +^

00

O (» i-H C St-, ^ O ^ O ^ o

d d d d d d +~-' +~-' +-

to CM

(M O OS CO wo

00

10 * 01 OS 1-H OS OS TJH 1-H (M W SS SS SS 00

o o 00 00 00 +^ 00

+

^ CO CI (N Tji OS CO

II II

oco ^co CO'* 00 lo" toco

II II II II II II II II

M pj O O O

H^-d o

I

I

II

II II

Table 8-23. Calculated contributions of independent vari- ables to the compressive strength 0/ mortar cubes, cured with

high-pressure steam after 5 hrs and tested dry (A UGR), and

the calculated ranges of such contributions

3alculatCoefficient Calculated ;d range Independ- Rang i of variable from eq (2) contribution of contri- ent variable (percent) table 8-22 to AUGR bution to (XlO-3) AUGR

(XlO-3)

Const.=-5. 291 C3A 1 to 15 +0. 1095 +0. 110 to +1. 642 1.532 C3S 20 to 65 +0. 1640 +3. 280 to +10. 660 7. 380 C2S 5 to 50 +0. 1540 +0. 770 to +7. 700 6.930 SOs -- 1. 2 to 3.

0

+1.0753 +1. 290 to +3. 226 1.936 Na20 0 to 0.7 -2. 676 0 to -1.873 1.873 WAGN.-.- 1200 to 3000 +0. 0030 +3. 600 to +9. 000 5. 400

Air, 1:4 1 to 21 —0. 1581 n 1 K.Q Q 1 RO 3. 004 mortar. Ba 0 to 0.2 -5. 169 0 to -1.034 1.034 Cu 0 to 0. 05 -22.02 0 to -1.101 1.101 Li 0 to 0. 02 +97. 92 0 to +1.958 1.958 Cr 0 to 0. 02 +38. 84 0 to +0. 777 0. 777 V** 0 to 0.1 -5. 71 0 to -0.571 0. 571

*cm2/g.

''Coefficient of doubtful significance as coef./s.d. ratio was less than 2.

5.6. Compressive Strength of Mortars, HighPressure-Steam-Cured after 24 Hr, and

Tested after Drying (AUMA)

The frequency distributions of the various types

of cements with respect to the compressive

strength of AUMA mortars are presented in table

8-24. As indicated in a previous subsection, these

mortars were autoclaved after 24 hr in the moist

closet and for a shorter period of time than the

AUGR specimens, the results of which were pre- sented in the previous subsection. The cements

within each of the types as classified had a broad

range of compressive-strength values and there was an overlapping of the strength values of the

cements of the different types. (See also fig. 8-1.)

Selected equations relating the AUMA compressive-strength values to various independent

variables are presented in table 8-25 for the

AE+NAE cements, and in table 8-26 for the

NAE cements.

Commonly determined variables having a coef./

s.d. ratio greater than one, as presented in eqs 1 and 4, resulted in a significantly lower S.D. value.

Table 8-24. Freguency distribution of cements with respect

to compressive strength of mortars, autoclaved after 2^ hr and tested after drying {AUMA)

Type cement

Compressive strength, psiXlO-'

Total

9.5 to

10.0

10.0 to

10.5

10.5 to

11.0

11.0 to

11.5

11.5 to

12.0

12.0 to

12.5

12.5 to

13.0

13.0 to

13.5

13.5 to

14.0

14.0 to

14.5

14.5 to

15.0

15.0 to

15.5

15.5 to

16.0

Number of cements

I 11 3

1 2 10 53

4

12 14

1 13

13

1 12

14

1 1 1 63

61

217

1 14

lA

II .- 1 5 13 5 1 IIA 1 III 1 6 5 1 IIIA 1 IV, v 9 5 4 1 1 1

Total 2 4 3 15 14 19 29 36 19 12 8 2 2 165

81
G

1 00

i S

; d

; B

; d

: i

; d

: s

: d

0.7528 0.7212

: §

: d

0.

7472

0.7197

>

-4.

56

(3.90)

*-0.01

(5.21) -9.

71

(6.40) -6.

17

(3.87) -5.20

(3.99) -6.6 2

(3.99)

-2.91

(6.28)

-10.

06

(6.

58)

CQ

1

1

i SS s§ g2 ;

i fe fs 7s fs i

: S5S S§ gfe

1 fB ,s fs fs

-99.

24

(36.

13)

-107.

31

(50.

87)

-76.

58

(53.

96)

-88.

24

(36.

42)

-90.

85

(36.

30)

—82.

74

(36.

92)

-111.82 (52.

11)

*-36.

64

(55.

16)

%

-1.434 (0.

768)

•-0.

139

(1.257) -2.

343

(1.022)

-1.861 (0.

770)

-1.302 (0.

762)

-1.705 (0.

759)

*-0.

156

(1.

259)

-2.

772

(1.050)

+0.

1499

(0.

0558)

+0.

1198

(0.

0544)

+0.

0968

(0.

0546)

+0.

1229

(0.0794)

+0.

1303

(0.

0869)

1

a 11 11 11 11 il Ii i! if if ll

°S t's ts °s °s oo

Air

1:4

mortar .1 ii if if if if if if if ll

°s fs fs fs fs fs fs

Iz: o

< ii +0.

00103

(0.00030)

i p }1

5

1

p fl fl f

+0.

000658

(0.

000149)

+0.000496 d

1

i i

i o

M il si ll m m il si si m m

i° 7s 7s 7"s 7° 7s 7s 7s 7s 70

o

s il si il ii ii ii si si m il

(NO -Jd -H-o -Id -Id -H-d ,H-d rtd 1— 1- 1-^ 1"- 1 I"-' 1^ 1^ 1- 1^

i

Ii ii ^1 il is Bl il ii il

°s 7s 7s 7s ^s 73 7s 7s 70 7s

o1

+0.

2460

(0.

0846)

+0.

2360

(0.

0821)

+0.

2051

(0.

0827)

+0.

2196

(0.

1212)

+0.

1891

(0.

1242)

i +0.

3488

(0.

0678)

-j-U.

60LM

(0.

0712)

+0.

3118

(0.

0726)

+0.4048 (0.

1145)

+0.2649 (0.

1016)

+0.

0410

(0.

0117)

+0.

0457

(0.

0112)

+0.0499

(0.0159)

+0.

0446

(0.0174)

+0.

0410

2- ;

t -0.

0710

(0.

0271)

-0.0595 (0.

0283)

-0.

0772

(0.0430)

-0.

0484

(0.

0414)

-0.

0477

(0.

0295)

I

AUMA

=

+9.784

s.d.

=

(0.776)

AUMA

=

+9.960

s.d.

=

(0.

765)

AUMA

(odd)

=

+9.935

s.d.

=

(1.144)

AUMA

(even)

=

+10.

146

s.d.

=

(1.155)

AUMA

=

+9.698

s.d.

=

(0.

830)

AUMA

=

+1.252

s.d.

=

(1.895)

AUMA

=

+1.452

s.d.

=

(1.950)

AUMA

=

+2.614

s.d.

=

(1.909)

AUMA

(odd

=

+1.972

s.d.

=

(3.

009)

AUMA

(even)

=

+4.

166

s.d.

=

(2.

759)

1 ££££££££££

i i J d

<

82
d s

o

0.

6993

0.7414 0.6874 0.

7030

0.7449 0.

7083

0.

7159

0.

7562

0.6974

>

1 sfe t2§ S3S ;

; «s «is ;

*-3.90

(3.96)

-5.30 (3.97)

•+0.

74

(6.47)

-9.72 (5.35)

: Sfi si 1

: fsi "fs 7a i

-3.09

(2.17)

-3.06 (2.20) -6.

17

(3.61)

•+0.

26

(3.29)

StP5 -100.

57

(35.

77)

—120.

55

(51.

70)

-51.90 (55.

35)

-90.

87

(36.

16)

-89.38

(35.95) -83.

35

(36.

65)

-118.

92

(52.

95)

*-12.79 (56.

51)

%

: il si II II i

i 7s 76 i

1 * •

: il il il ii

i 7° 70 76 7d

1

i

i i

+0.

1566

(0.

0558)

+0.

1261

(0.

0540)

+0.

1020

(0.

5455)

+0.

1010

(0.0803)

+0.

1661

(0.

0852)

1

«i II g| Il g| If 2| Il ii |i

^d -id -n'd rt"d -Jd -Id ria dd -^d dd

i! il If il il il il if ii if

fs -fs °s =s fs °s °s fs °s

o +0.00102 (0.

00030)

i i

+0.

00081

(0.

00029)

+0.

00107

(0.'

00045)

+0.

00058

+0.000699

+0.

000562 Illili +0.

000653

(0.

000149)

+0.

000485 1

s -1.

334

(0.

340)

—

1.004 (0.

353)

-0.813 (0.

574)

-1.584 (0.

542)

-1.112 (0.

348)

-1.352 (0.

365)

-1.002 (0.

376)

-1.116 (0.

374)

-0.

823

(0.

619)

-1.800 (0.

539)

q 13 il ii Ii s§ If il si ii if

«d|w rJd wd rid ^-d ^-d .-Id rtd -Id ^-d 1^ 1 1^ I- 1^ 1- 1- 1^ 1

s Il §1 il gl il sl 5l ii il si

dd -H-d ^'d -Id ^d -Id rH-d -id -id -Id +- +- +- +- +- +^ +- +- +- +°

1 +0.

2187

(0.

0849)

+0.

2048

(0.

0820)

+0.

1819

+0.

1813

(0.

1347)

+0.

1815

(0.

1152)

i +0.

3686

(0.

0683)

+0.

3711

(0.

0707)

+0.

3232

(0.

0724)

+0.

3650

(0.

1204)

+0.

3158

(0.0965)

3 +0.0438 (0.

0119)

+0.

0493

(0.

0113)

+0.

0466

(0.

0159)

+0.0548 (0.

0194)

+0.0442

s

-0.0669 (0.

0276)

-0.0486 (0.

0284)

-0.0653 (0.

0443)

•

-0.0331 (0.

0474)

-0.0386 (0.

0295)

i

1

AUMA

=

+9.859

s.d.

=

(0.

797)

AUMA

=

+9.935

s.d.

=

(0.

772)

AUMA

(odd)

=

+9.

705

s.d.

=

(1.093)

AUMA

(even)

=+10.128

s.d.

=

(1.

232)

s.d.

=

(0.

855)

AUMA

=

+1.066

s.d.

=

(1.903)

AUMA

=

+1.525

s.d.

=

(1.939)

AUMA

=

+2.585

s.d.

=

(1.910)

AUMA

(odd)

=

+0.

932

s.d.

=

(3.112)

AUMA

(even)

=

+3.

075

s.d.

=

(2.

644)

1

Equation < 10 0

<CD i
With the addition of the 4 trace elements, SrO,

Rb, Ba, and V in eqs 2 and 6, further significant

reductions in the S.D. values were attained al- though the coefficients for neither SrO, Ba, nor V

were highly significant. In this case, unlike those

presented above, the use of air-permeability rather

than Wagner fineness (eq 3) did not result in an

increased S.D.

In eqs 2A and 2B calculated for the "odds"

and "evens" in the array of cements, brO, Ba,

and V, as well as Insol, had coef./s.d. ratios less than one in one or the other of the equations.

In eqs 6A, and 6B, lib also had a coef./s.d. ratio

less than 1. The equations calculated for the NAE cements

alone, presented in table 8-26, are in close agree- ment with those calculated for both AE and NAE

cements. It may be noted, however, that the

coeflficient for C3A which was of questionable

significance in eq 2 and 3 had a coef./s.d. ratio

Table 8-27. Calculated contributions of independent vari- ables to the compressive strength of mortar cubes, cured with

high-pressure steam after 24 hrs, and tested dry, (A UMA)

and the calculated ranges of such contributions

Independent

variable

Range of variable

(percent)

Coefficient from eq (3) table 8-26Calculated

contribution toAUMA(X10-3)

Calculated range

01 contri- bution

to AUMA

(XlO-3)

Const. =+9.648 CiA" 1 to 16 -0. 0386 -0. 039 to -0. 579 0. 540 C2S 5 to 50 +0.0442 +0. 221 to +2. 210 1.989 SO3 1. 2 to 3.

+1.370 +1.644 to +4.110 2. 466 NajO 0 to 0.

-1.815 0 to -1.271 1.271 K2O 0 to 1.

-1.112 0 to -1. 223 1.223 WAGN._. •1200 to 3000 +0. 00102 +1. 224 to +3. 060 1.836

Air, 1:4 mortar**- 1 to 21 -0. 0618 -0. 062 to -1. 298 1.236

Insol - 0 to 1.0 -1. 135 0 to -1. 135 1.135 SrO 0 to 0.

-2. 194 0 to -0. 878 0. 878 Rb 0 to 0. 01 -90. 87 0 to -0.909 0. 909 Ba'* 0 to 0.

-3.04 0 to -0. 608 0. 608 V" 0 to 0.

-4.83 0 to -0. 483 0.483

*cm2/g-

•'Coefficient of dubtful significance as coef./s.d. ratio was less than 2.

less than 1 in eq 2B. The variable (air, 1 :4 mortar)

also had coef./s.d. ratios less than one in eqs 2B

and 6B in table 8-26 for the NAE cements.

The estimated contributions of the different

variables to the compressive strength were cal- culated from their coefficients as obtained in eq

3 of table 8-26 and are presented in table 8-27

together with the calculated ranges of contributions to the compressive strength. Increases in

C2S, SO3, and fineness were associated with higher

compressive strength values. Increases in Na20,

K2O, SrO, Rb, and possibly Insol, were associated

with lower strength values. Increases in C3A, air content, Ba, and V, though of doubtful signifi- cance, may possibly be associated with lower

compressive strength.

Table 8-28. "F" ratios for significance of reduction of variance due to added variables

Table EQuations "-T ratio U.t: . Critical 'F ratio a = 0.01 a =0.05

8-5 1,2 8. 16 3:139 3. 92 2.68 8-5 4,5 13. 65 2:137 4.75 3.07

8-6 1,2 7.20 3:131 3.93 2.68 8-6 4,5 10.99 2:129 4.76 3. 07

8-9 1,2 3. 43 5:133 3.16 2.28 8-9 4,5 5. 50 3:135 3. 92 2.68

8-10 1,2 3. 97 5:124 3. 16 2.28 8-10 4,5 5.02 3:126 3. 94 2.68

8-13 1,2 10. 16 3:135 3.92 2.68 8-13 4,5 10. 11 3:135 3. 92 2.68

8-14 1,2 9. 05 3:126 3. 94 2.68 8-14 4,5 9. 42 3:126 3.94 2.68

8-17 1,2 3.38 4:135 3. 46 2. 45

8-18 1,2 3.58 4:126 3. 47 2. 45

8-21 1,2 7.58 5:134 3. 16 2.28

8-21 4,5 7. 43 5:135 3.16 2.28

8-22 1,2 8. 07 5:125 3. 16 2.28 8-22 4,5 10. 14 5:126 3.16 2.28

8-25 1,2 4. 64 4:134 3.46 2.45 8-25 4,5 4. 07 4:133 3.46 2. 45

8-26 1,2 5. 18 4:126 3. 47 2.45 8-26 4,5 4. 42 4:125 3. 47 2.45

6. Discussion

6.1. Variables Associated With Strength After

Different Curing Conditions

In order to compare more easily the variables

associated with the compressive strength after

the different curing conditions, a single equation was selected from each of the previously presented

tables for the NAE cements. These are presented

in table 8-29. As in table 7-77 of the previous

section of this series of articles, the equations are here presented vertically instead of horizontally.

Also presented are the coef./s.d. ratios and the

calculated ranges of the contributions of the

different variables. A coef./s.d. ratio of 3 or greater is considered significant although there is a probability of one percent of this ratio occurring

by chance alone. Coef./s.d. ratios between 2 and

3 may indicate a significant relationship, whereas

if the value is below 2 it is questionable whether

the variable is truly significant and further

information relative to its role in affecting

compressive strength would be desirable.

In comparing the variables associated with the

compressive strength of moist-air-cured sjoecimens, WAGR, with those of the STGR and

STMA specimens, it may be noted that the variables C3A, SO3, and K2O may be associated with

the STGR values and are probably associated

with the STMA values. They did not appear in the equation for the normal-23 °C-cure, WAGR

values, because the coef./s.d. ratios were less than

1. It would appear then, that possible consideration should be given to variations of these variables and to P and Li in addition, in anj^ accel84
Table 8-29. Coeffcienls, coef./s.d. ratios, and calculated ranges of contributions of independent variables associated with compressive strength values after the different curing conditions '

Equation No.

Table No. 8-6 8-10 8-14 8-18 8-22

Dependent variable.

Constant, coef C3A, coef

coef./s.d calculated range*. C3S coef

coef./s.d calculated range.

C2S, coef

coef./s.d calculated range. C4AF, coef

coef./s.d calculated range.

SO3, coef -- coef./s.d calculated range.

Loss, coef

coef./s.d calculated range.

Insol, coef

coef./s.d calculated range. MgO, coef

coef,/s.d calculated range. NazO, coef

coef,/s.d calculated range. K2O, coef

coef./s.d... calculated range.. WAGN, coef

coef./s.d calculated range. Air 1:4 mortar, coef.

coef./s.d calculated range Ba, coef

coef./s.d calculated range.

Cr, coef

coef./s.d.- calculated range. Cu, coef. _. coef./s.d calculated rangeLi, coef

coef./s.d. calculated range.

P, coef

coef./s.d calculated range. Rb, coef

coef./s.d calculated range. SrO, coef

coef,/s.d calculated range. V, coef

coef./s.d calculated range.

WAGR

+3. 609

+0. 0413 5.5

1.858

WAMA

+2. 691

+0. 0823

2.8 1.152

+0. 0569 5.6 2.660

STGB

-2. 094

+0. 0475

2.4

0. 665

+0. 0853

10.4

3. 838

-0. 2000

2.3

0. 600

-0. 7850

2.3 0.785

'+0.0509 L6

0. 763

* '+0.4166

1.99

0. 750

-0. 3200

2.7

0. 960

-0. 8495

1.9

0. 850

+0. 4949

2.9

0. 891 -0.3111

3.2

0.933

-0. 3843

1.01 0.269

+0. 00180

9.5 3.240 -0. 1420 5.6

2. 840 -3. 71 2.7 0.742

+0. 00174

6.2

3. 132

-0. 1407 3.8

2.814

-4. 772

2.7

0. 954

+0. 5892

2.3 0.648 +0. 00223

9.3

4. 014

-0. 0967 3.4

1.934

-5. 64 3.8

1.128

-17. 81 3.3

0. 890

-9.37

1.3

0. 468

-6.98

1.2 0.349

-1.46 3.4

0. 730

STMA

-3. 092

+0. 0512

3.5 0.717

+0. 0749

11.7 3.370

AUGR

-5. 291

+0. 1095 3.7

1.533

+0. 1640 5.9

7. 380

+0. 1540

5.3 6.930

+0. 5280 3.8

0. 950

-0. 3954

5.6

1. 186

-0. 0525

1.5 0.262

+0. 6548

3.1 0.720

+0. 00175 9.2 3.150

-0. 0951 4.0

1.902

-3. 021 2.6 0.604

-10.31

2.2

0. 515

+26. 97

2.3 0.539

-1.325

1.8

.0.530

+1. 0753 4.4

1.936

-2. 676 6.8

1.873

+0. 00300

10.0 5.400

-0. 1581

4.1

3. 162

-5. 169

2.5

1.034

+38. 84

2.7 0.777 -22.02

3.0

1.101

+97. 92 5.0

1.958

-5. 71 1.5

0. 571

AUMA

+9. 648

* -0.0386

1.3

0. 540

+0. 0442

4.0

1.989

+1. 370

6.4

2.466

-1. 135

2.3

1. 135

-1.815

4.4

1.270 -1.112

3.2

1. 223

+0. 00102 3.4

1.836 *-0.0618

1.6 1.236 »-3. 04

1.4 0.608

-90. 87

2.5 0.909

-2. 194

*-4.83

1.3 0.483

' The coefficients and calculated ranges of their contributions must be multiplied by 10004e obtain the respective values in psi. •The calculated range was computed from the range of values for the cements times the coefficient for each of the independent variables. **The independent variable is probably not significant as the coef./s.d. ratio Is less than 2.

85
erated strength test of mortars if cements of

different composition are involved. This could

apply to cement from a single source as well as cements from different sources. The variables C3A, C3S, and C2S were all asso- ciated with the compressive strength of AUGR

specimens, autoclaved after 5 hr of moist curing

but, of these, only C2S was associated with the

compressive strength of the .A.UMA specimens,

autoclaved after 24 hr. The coefficient for SO3 was

significant in both the AUGR and AUMA equations as well as in the STMA equations but of

borderline significance in the STGE, equation.

(In table 7-77 of the previous section, the coeffi- cient for SO3 was probably significant at 1, 3 and

7 days but not at 28 days for the water-stored

1:2.75 mortars.) The coef./s.d. for SO3 was less than 1 in the equation WAGE, for 28-day moistair-cured specimens in this series of tests. The

SO3 contents of the cements were probably lower

than the optimum values, or than those permitted

in present specifications. To extrapolate the effects of SO3 to the higher values now permitted may be

of questionable value.

The coefficients for Wagner fineness of the ce- ments were highly significant and related to the

compressive strength with each of the curing conditions used. Although the equations in this table were for NAE cements, the coefficient for (air,

1 :4 mortar) were significant at the one-percent

level for all but the AUMA specimens. (Where

the AE cements were included in table 8-25, the

coefficient for air entrainment was also significant

in this case.)

The coefficients for Loss-on-ignition were significant in equations for the low-pressure-steamcured specimens, were possibly significant in equations for specimens cured at normal temperatures,

but had coef./s.d. values less than 1 in the equations for the autoclaved specimens.

The coefficient for Na20 was significant with

both autoclave treatments and the coefficients

had negative signs. (Referring back to table 7-77

of the previous section, the coefficients for Na20

were also significant and -with a negative sign for the 1, 5, and 10-year tests of the 1:2.75 mortar

but were not significant at the early ages.) The

coefficients for K2O were probably significant, and

were positive in equations for the low-pressuresteam-cured specimens. This variable had a coef./

s.d. ratio less than 1 in the equations for AUGR

but appeared significant, having a negative sign

in the AUMA equation. (The coefficient for K2O

was significant and positive at 1 day, and probably

significant at 3 and 7 day tests but not at later ages as reported in table 7-77 of the previous

section.)

Of the other alkalies, the coefficient for Li was

significant in the equation for the AUGR specimens, and possibly so for the equation for STMA

specimens. The coefficient for Rb was significant at the 5-percent level in the equations for AUMA

specimens. The coefficients for Li were positive, I whereas that for Rb was negative. I The coefficients for the other trace elements 1 were, in general, not highly significant, and except J for Ba and Cu, not found consistently in equations

for compressive strength after the different curing | treatments. The coeflBcient for Ba was significant J in the STGR equation and possibly significant in

the others except the AUMA equation. Cu had a

coef./s.d. ratio greater than 3 for the 28 day moist- l\ air-stored, and the AUGR specimens but the coefficient was probably not significant under the

other curing conditions. \ Reference was previously made to differences

in the variables associated with the low-pressure- i steam-cured compressive strength and the strength i obtained after ciu-ing at normal temperatures. The ! last 2 equations in table 8-29 indicate that the

| variables can also differ, depending on either the ! age at which the specimens are autoclaved, (5 or 24 hr) or the period of autoclaving (11 hr or 4 hr) for the AUGR and AUMA specimens respectively.

The curing cycle used for the AUMA specimens ; would be preferable for use as a laboratory test 1 method because of the difficulty of removing speci- I mens from their molds at 5 hr or earlier as used : in commercial practice.

4 : t

6.2. Relationship of Compressive Strength i Values of 1:3.525 (Cement to Silica) Mor- ! tars When Cured Under Different Con- j ditions

j

I A series of linear equations are presented in ! table 8-30 to indicate the relationships between

j compressive strengths of the mortars of this series achieved by different curing methods. Presented

also are values for reduction in variance, "F"

values, resulting from the use of these equations. , "F" values, greater than 4.75 (for 2:150 degrees

of freedom) or 5.03 (for 2:55 degrees of freedom)

are significant at the 1 percent level. Each of the

equations indicated that there was a statistically

significant relationship. It may be noted, however,

that the "F" values ranged from a low of 6.8 to a high of 656.

Plots were made of the relationships of the

compressive-strength values obtained when using .| the different curing conditions. Six of these plots

| were selected to illustrate the spread of test values

| corresponding to a range of S.D. and "F" values

obtained in some of the equations of table 8-30, 1 namely the first 5 equations -and eq (18) which

had the highest "F" values in this series. These v plots were all made using the same scale ranges, 6 but it was necessary to shift the origin of the I scale to accommodate the different values. These ' plots do not fully indicate the concentration of points where one dot on the grid may represent more than one value when plotted by means of 1 the computer. I

86
Table 8-30. Relationships of compressive strengths of mortar cubes, cured and tested under various conditions as indicated in

the text (see p. 69)

Equation

Dependent

variable Const. Independent

variable S.D. D.F.

1-

2..

3..

4..

6_.

6-

7-

8..

9..

10.

11.

12.

13.

14.

15.

16.

17.

18.

19.

20.

21.

22.

23.

24.

WAGR= s.d. WAGE

s.d. WAGR = s.d. WAGR= s.d. WAGR= s.d. WAMA=

s.d. WAMA=

s.d. WAMA=

s.d. WAMA=

s.d. STGR

s.d. STGR =

s.d. STRG =

s.d. STMA =

s.d. STMA =

s.d. AUGR=

s.d. AUGR=

s.d. AUGR=

s.d. DRYS =

s.d. WAGR=

s.d. WAMA=

s.d. STGR =

s.d. STMA =

s.d. AUGR= s.d. AUMA= s.d.

+0. 348

(0. 245)

+2. 937

(0. 234) +3. 960

(0. 207)

+0. 743

(0. 521)

+2. 964

{0. 753) +0. 964

(0. 271) +3. 487

(0. 245) +4. 469

(0. 190) +1. 405

(0. 617)

+1. 678

(0. 164) -1. 244

(0. 687)

+2. 329

(0. 979) -1.434

(0. 588) +1. 226

(0. 793)

+8. 239

(0. 468) +9.682

(0. 406)

+3. 437

(0. 913) +1.636

(0. 166) +3. 234

(0. 282)

+3. 597

(0. 269)

+0. 953

(0. 338) -0. 820

(0. 220) +8. 868

(0. 628)

+10. 81

(0. 56)

+0. 805

(0. 028)

+0. 675

(0. 036) +0. 811

(0. 049) +0. 488

(0. 039)

+0. 339

(0. 059) +1. 052

(. 037)

+0. 797

(0. 037)

+1. 012

(0. 045)

+0. 539

(0. 046)

+1. 163

(0. 039)

+0. 574

(0. 051)

+0. 332

(0. 076)

+0. 414

(0. 044)

+0. 227

(0. 062)

+0. 805

(0. 071)

+0. 913

(0. 096)

+0. 782

(0. 071)

+1. 165

(0. 032) +0. 877

(0. 055) +1. 087

(0. 062)

+1. 178

(0. 065)

+1. 043

(0. 043)

+0. 993

(0. 122)

+0. 475

(0. 109)

WAMA

STGR

STMA

AUGR

AUMA

WAGR

STGR

STMA

AUGR

STMA

AUGR

AUMA

AUGR

AUMA

STGR

STMA

AUMA

WETS

WETS

WETS

WETS

WETS

WETS

WETS

0. 360

0.497

0. 544

0. 637

0.830

0. 411

0.520

0.500

0.754

0. 431

0.840

1.078

0. 720

0. 873

0.994

1. 069

1.006

0.244

0.415

0.396

0.496

0. 323

0. 924

0.828

410

180

138

80

17

410

229

254

70

451

64

10

45

6.1

64

45

61

656

129

217

162

300

33

9

2:149

2:149

2:149

2:149

2:149

2:149

2:149

2:149

2:149

2:149

2:149

2:149

2:149

2:149

2:149

2:149

2:149

2:55

2:55

2:55

2:55

2:55

2:55

2:55

It may be noted in figure 8-2, a plot of the

relationship presented in eqs 5 of table 8-30 that

there is a considerable scatter of results. The "F"

value was 17. There appears to be somewhat less scatter in figure 8-3 (eq 4 table 8-30, "F" value

80). In figures 8-4 and 8-5 and 8-6 with "F"

values of 138, 180, and 410 respectively, (eqs 3, 2, and 1 of table 8-30) there was less scatter as the

"F" values increased. The values for the WETS

and DEYS (both steam cured for 24 hr), when

plotted in figure 8-7, do not indicate as broad a band as was indicated in the previous figures.

There were fewer values plotted and used in the

equation (eq 18 table 8-30, "F" value of 656).

It may be noted in table 8-30 that the numerical

values for "F" in eqs 7 and 8 are slightly higher

than those of eqs 2 and 3. This may then indicate

that the compressive strength of steam-cured

specimens, STGK and STMA, are more reliable

in predicting the compressive strength of the 28-

day specimens, air-dried for 2 weeks before testing,

W.A.MA, than those cured continuously in moist

air for the 28 days, WAGR. The numerical value

for "F" in eq 10 relating the compressive strength

87

I
T

9.0

g

X

8.0

q:i

q:

>

LU

q:a.o

o

70

6.0-

5.0-

8.0 10.0 12.0 14.0 16.0 COMPRESSIVE STRENGTH AUMA, psi. X lO'^

18.0

Figure 8-2. Results of plotting the 28 day compressive strength of moist-air-siored mortar cubes

versus the compressive strength of cubes of identical mortars, moist cured for 24 hr, then autoclaved at 10 atm for 4 hr, then oven dried.

(See eq 5, table 8-30.)

of STGK and STMA, (the one steam cured after 5 hr, the other after 24 hr) was 451 which would

indicate a rather small scatter of points. The "F"

of eq 17 relating the compressive strength of AUMA and AUGR (the one autoclaved after 24

hr and the other after 5 hr) was 61, and, judging

by figure 8-3, this would indicate a fairly broad

scatter of points. This then indicates that a laboratory evaluation test of the suitability of a cement

or other ingredients used in autoclaved-cured

products must simulate as closely as possible the

curing cycle or cycles employed in the commercial

production. It is also indicated that, with some

cements, higher strength values can be obtained

by autoclaving after a 24-hr presteaming period

but with other cements a shorter period may be

advantageous.

Reference has been made in previous subsections

and tables 8-4, 8-8, 8-12, 8-16, 8-20 and 8-24 to the frequency distributions of the strength values

of the different types of cement after the different

curing conditions. In most of these tables, the

values for the Type III cements were generally

among the upper values in the frequency-distribution curves for all the cements. The cements

classified as Types IV, V had 28-day compressive

strength values about the same as for all cements

for the moist-air-stored specimens, WAGR, (table j 8-4) and when moist-air-cured for only 14 days

j and then air-dried, WAMA, (table 8-8) but their

strength values Avere relatively low when cured by ( low-pressure steam, STGR, STMA (tables 8-12 j and 8-16). When autoclaved after 5 hr, AUGR, ; the average compressive strength values were about the same as the average of all cements (table

8-20), but if autoclaved after 24 hr, AUM.A., the

the strengths were generally above the average of *

all combined (table 8-24). The broad overlapping

and range of the compressive strength vlaues of the Types I and II cements make it impossible to attribute any advantage to either of these types

in so far as compressive strength is concerned.

The frequency-distribution curves for all the

cements indicated considerable overlapping of the

| compressive-strength values when the cements 'i were cured under the different conditions. This has

been indicated in figure 8-1. In comparing these ,•; distribution curves, consideration must also be « given to the time of curing as well as to whether s the specimens were tested in a wet or dry condition. | The high-pressure-steam-cured specimens

| AUMA and AUGR had higher compressive c strengths than either those cured in moist air or those cured in steam at atmospheric pressure

88
8.0 10.0 12.0 14.0 16.0 COMPRESSIVE STRENGTH AUGR, psi. X lO'^

18.0

Figure 8-3. Results of plotting the 28 day compressive strength of moist-air-stored mortar cubes

versus the compressive strength of cubes of identical mortars, moist cured for 5 hr, then autoclaved at 10 aim for 11 hr, then oven dried.

(See eq 4, table 8-30.)

STGK and STMA. The distribution curves for the low-pressure-steam-cured specimens STMA

and STGE, indicated lower compressive strengths

than the 28-day moist-air-cured WAGE,, or the

WAMA specimens which had 14 days of moist

curing and then 14 days of air drying. For both

steam-cured and autoclaved specimens, those

which started steam curing green achieved significantly higher average strength than those

whose curing started at 24 hr.

Table 8-31. Comparison of average compressive strengths and

S.D. values obtained for the cements when cured and tested under the different conditions as explained in the text AE+NAE cements NAE cements

Identifica- tion Comp. S.D. Coef. of Comp. S.D. Coef. of strength variation strength variation

p.s.i. p.s.i. % p.s.i. p.s.i. %

WAGE-.. 7323 907 12.4 7377 879 11.9 WAMA.... 8653 1037 12.0 8699 1028 11.8 STGR 6491 1141 17.6 6535 1140 17.4 STMA 4119 903 21.9 4133 908 22.0 AUGR... 13414 1332 9.9 13493 1301 9.6 AIJMA.... 12804 1150 9.0 12847 1139 8.9 WETS 5063 1014 20.0 DRYS.... 7535 1206 16.0

The average compressive-strength values previously presented in individual tables are summarized in table 8-31 together mth calculated

CO efficient-of-variation values. The averages coincide fairly closely with the maxima of the fre- quency distribution curves. The curves presented in figure 8-8 are regression

lines drawn from equations relating the 28-day

moist-air-ciu-ed compressive strength values WAGE,

to those obtained after the other curing conditions.

A limited number of cements (65) were available

for the WETS and DRYS (curves 2 and 4), and

because of this, only the same cements were used

in computing the other relationships. The cements

used in the equations for figure 8-8 had STGR

and STMA compressive-strength values about 400

psi higher than the averages for all the cements for

the same curing conditions. The calculated S.D.

values were also slightly greater than when all cements were included. Included also is the line

denoting equality (dashed line labeled 5). The

longer steaming period for the WETS, 24 hr at 66° C (curve 2) agamst hr at 71° C for STMA

(curve 1) increased the strength values to some

extent. Both groups of cement mortars were tested

when wet, but were also both below those of

89
X

hC3

>

CO<o

LU

OCa.s

o

o

2.0 4.0 60 8.0 COMPRESSIVE STRENGTH STMA,

10.0 12.0

psi. X 10"

Figure 8-4. Results of plotting the 28 day compressive strength of moist-air-stored mortar cubes

versus the compressive strength of cubes of identical mortars, moist cured for 24 hr, then steam

cured at 71 °C for 7.5 hr and tested wet.

(See eq 3, table 8-30.)

curve 5. Similarly, the DRYS, steam cured 24 hr

and air dried, (curve 4) indicated somewhat higher

strength values than the STGR specimens (curve

3) steam cured about 12 hr then air-dried. The

DRYS (curve 4) also had higher strength values

than the WETS (curve 2). The curves 3 and 4

(STGR and DRYS) may be compared to curve 6

for specimens cured at normal temperatures 14

days and then air-dried WAMA. Although it appears that the slopes of many of the curves in this

figure, especially 7 and 8, are much lower than

that of line 5, this is probably not significant.

Reference should again be made to figures 8-2

and 8-3 to appreciate the scatter that the computed curves in figure 8-8 do not indicate. The

curves presented in figure 8-8 indicate only the

general trends of the results obtained with the

particular mortar used and the relative positions on the strength scale of the values obtained after the various curing conditions.

6.3. Estimated Standard Deviation of

Duplicate Tests

The estimated standard deviations of duplicate

determinations of the compressive strength values

are presented in table 8-32. Also presented in this

table are the S.D. values of calculated equations

relating the various independent variables to the

dependent variable. The equations selected for

this piu-pose were the same as those used in table

8-29. The S.D. values of the duplicates were

smaller than those of the equations in every in- stance. The S.D. values of the autoclaved specimens, AUGR and AUMA most nearly approached

the S.D. values of the duplicates as indicated by

the ratios in the last column.

6.4. Relationship of Compressive-Strength of

Mortars in This Series to Those of 1:2.75

(Cement to Sand) Mortars Presented in

the Previous Section

Another series of equations are presented in table 8-33 to indicate the relationship of the

compressive-strength values of the 1:3.525 (cement to silica) mortars of this section, cured

under different conditions to some of the strength

values of 28 days to 5 years of the 1 :2.75 (cement

to graded Ottawa sand) mortars as reported in section 7 of this series. Presented also are the S.D.

values, and the reduction in variance ("F"

values) resulting from the fitting of the equations.

With the number of degrees of freedom involved.

90
a:o

<

X

I-o

LlI

>

COw

Ijj tr

Q.

m.o

o

4.0 6.0 8.0 10.0 COMPRESSIVE STRENGTH STGR, psi. XIO"^

2.0

Figure 8-5. Results of plotting the 28 day compressive strength of moist-air-cured mortar cubes

versus the compressive strength of cubes of identical mortars, moist cured for 5 hr then steam

cured at 66 °C for 12 hr, then air-dried at 23 °C, 50 percent R.H.

(See eq 2, table 8-30.)

Table 8-32. Comparison of S.D. values of pairs of duplicate determinations with those obtained in the fitted equations

Identification No. of S.D. of S.D. of Ratio of duplicates duplicates equations S.D. values WAGE 21 248 524 2.11 WAMA 21 391 643 1.64 STGR 21 350 544 1.55 STMA 20 163 414 2. 54 AUGR ._ 2r 586 671 1.15 AUMA 21 511 699 1.37 WETS__ 10 184 DRYS 10 376

there was evidence of a relationship at the 1 percent probability level in all but eqs 28, 39, and 40. Other equations where the 5 year compressive

]i strength values were used as the dependent

variable (eqs 25, 26, 27, 29 and 30) also had

j relatively low numerical values for the reduction

j in variance when compared to eqs 1 and 2 where

the age and curing conditions were more nearly

' the same. The relationship of the compressive

strength of low-pressure-steam-cured specimens,

to the 28-day compressive strength of the 1:2.75

mortars (eqs 3, 4, 31, and 32) had intermediate

"F" values ranging from 78 to 132. The reduction

' in variance in eqs 5 and 6, relating the com1

pressive strength of the autoclaved specimens to the 28 day strengths of the 1:2.75 mortars gave

"F" values of 13 and 45. The reduction in variance

values in eqs 9, 10, 11, 12, 15, 16, 17, 18, 21, 22, 23,

24, and 33 through 38, relating the compressive

strengths of steam cured and autoclaved speci- mens to the 1-year compressive strengths of the

1:2.75 mortars were generally fairly low.

It was indicated in both figure 8-1 and in eqs

1 and 7 of table 8-33 that the compressive strengths

of the 28-day moist-air-cured specimens, WAGR,

were generally higher than those of the 1:2.75

(cement to sand) standard test mortars after both

28-day and 1-year water storage. A number of factors may be involved, including the pozzolanic

action of the hydration products with the fine

sUica, the gradation of the sand, ratio of fines to coarse material, or possibly a lower air content.

6.5. Mix Proportions

The mix proportion used in the present series of tests was designed primarily with high-pressuresteam curing requirements in mind, where the use of finely ground sdica or other pozzolanic

material is highly desirable. The distributions of

91
IT

Q.O

5.0

2,0 4.0 6.0 8.0 COMPRESSIVE STRENGTH WAMA, psi. X 10

10.0 -3

12.0

Figure 8-6. Results of plotting the 28 day compressive strength of moist-air-cured mortar cubes

versus the compressive strength of cubes of identical mortars, moist-air-cured for I4 days, then

dried at 23 °C, 50 percent R.H. for I4 days and tested dry.

(See eq 1, table 8-30.)

fines to coarse materials were computed three

ways as follows:

A. (1 cement +0.19 sand pass #200 sieve) to 2.81 sand retained #200 sieve

B. (1 cement +0.24 sand pass #140 sieve) to 2.52 sand retained #140 sieve

C. (1 cement +0.43 sand pass #100 sieve) to 2.16 sand retained #100 sieve

In A, 16 percent of the cement may be considered replaced with finer sUica, in B, 19 percent,

and in C, 30 percent depending on whether the

percentage passing the No. 200, the No. 140 or the No. 100 sieve is taken as the dividing line

between reactive and nonreactive sUica. Because

of the fineness of the silica flour used in this series of tests, some pozzolanic activity may be expected

at temperatures used for the low-pressiu-e-steam

curing and possibly also at laboratory temperatures. The quantity of silica fines used was lower

than that found by Menzel [7] to give the optimum

strength but it was considered that the fineness of the sUica flour must also be taken into

consideration.

6.6. Compressive Strength Versus Time of Set

A particular penetration resistance as determined by the time-of-setting vtest has been pro- posed as a criterion for the time at which steam

curing of concrete specimens for purpose of accel- erated testing should be started [19]. It was not

possible in the present study to make time-of-set

tests on the mortars and to use different times

for starting the heating or steaming cycle. However, calculations were made of the relationships

of the compressive strength values with the times

of initial and flnal set of the neat portland cements.

The results of these calculations are presented in table 8-34. The "F" ratio for reduction in vari- ance must exceed 3.05 or 7.4 to indicate a significant relationship at the 5- or 1-percent probability

levels, respectively.

A longer time of initial set of the neat cement

may be associated (see eq 1) with a lower compressive strength when the low-pressure steam

curing of the mortars was started at about 5 hr

(STGR) and with a higher compressive strength

(see eq 6) when the low-pressure steam curing was started after 24 hr. (STMA). There was no

92
2.0 40 6.0 8.0 10.0 COMPRESSIVE STRENGTH DRYS, psi. X 10"'

12.0

Figure 8-7. Results of plotting the compressive strength of mortar cubes, moist-air-cured for 24 hours then steam cured for 24 hr and tested, versus the compressive strength of cubes of identical mortars which had an additional 14 days of air-drying at 23 °C 50 percent R.H.

(See eq 15, table 8-30.)

Figure 8-8. Curves drawn from regression equations calculated for the 66 cements used for the "WETS" and "DRYS" and moist-air cured for 28 days versus the compressive strength of

the same cements cured and tested under the various conditions. (1=WAGR versus STMA, 2=WAGR versus WETS, 3=WAGR versus STGR, 4=WAGR versus DRYS, 5=45°

equality line, 6=WAGR versus WAMA, 7=WAGR versus AUMA,8=WAGR versus AUGR. See text and table 8-3 for notations and details of curing and testing conditions.)

276-694 0-68—

7
Table 8-33. Relationships of compressive strengths of the mortars of this series to those of the standard 1:2.76 {cement to Ottawa ^ sand) mortars of section 7

Equation

9._

10_

13..

14_

15_.

16_

17..

18..

19_.

20..

21..

22..

23..

24_.

25_.

26_

27..

28_.

29.

30_

31.

Dependent

variable Const. Independent

variable S.D. "F" D.F.

ST28 =

s.d. =

-1. 108

(0. 291) +0.846 WAGR(0. 040)

0. 439 229 2:146

ST28 =

s.d. =

-1. 296

(0. 306) +0.738 WAMA

(0. 035) 0.446 220 2:146

ST28 =

s.d. =

+1. 121

(0. 264) +0.611 STGR

(0. 040)

0. 655 117 2:146

ST28 =

s.d. =

+1. 835

(0. 205) +0.787 STMA

(0. 048)

0. 534 132 2:146

ST28 =

S.d. =

-0. 336

(0. 578) +0.403 AUGR(0. 043) 0.705 45 2:146

ST28 =

s.d. =

+1. 233

(0. 746) +0.301 AUMA(0. 058) 0.821 13 2:146

ST1Y =

s.d. =

+2. 192

(0. 441) +0.560 WAGR(0.060)

0. 665 44 2:146 ST1Y=

s.d. =

+2. 855

(0. 502) +0.397 WAMA

(0. 058)

0. 730 24 2:146 ST1Y=

s.d. =

+4. 814

(0. 380) +0.227 STGR(0. 058) 0.800 7.8 2:146

ST1Y=

s.d. =

+5. 345

(0. 313) +0.229 STMA

(0. 074)

0. 815 4.8 2:146

ST1Y=

s.d. =

+1. 235

(0. 546) +0.376 AUGR

(0. 040) 0.666 43 2 :146

ST1Y=

s.d. =

+0. 854

(0. 616) +0.424 AUMA(0. 048)

0. 678 39 2:146

ST1A =

s.d. =

+0. 929

(0. 320) +0.596 WAGR

(0. 043) 0.482 94 2:146

ST1A=

s.d. =

+0. 943

(0. 346) +0.502 WAMA(0. 040) 0.504 80 2:146

ST1A=

s.d. =

+2. 242

(0. 234) +0.469 STGR(0. 035) 0.492 87 2:146

ST1A=

s.d. =

+2. 831

(0. 188) +0.595 STMA(0. 044) 0.488 90 2:146

ST1A=

s.d. =

+0. 820

(0. 469) +0.469 AUGR

(0. 035)

0. 571 46 2:146

ST1A =

s.d. =

+2. 112

(0. 608) +0.248 AUMA(0. 047)

0. 669 14 2:146

ST1M=

s.d. =

+1. 398

(0. 441) +0.722 WAGR

(0. 060)

0. 605 73 2:146

ST1M=

s.d. =

+1.968

(0. 511) +0.545 WAMA

(0. 059) 0.745 43 2:146

ST1M=

s.d. =

+4. 197

(0. 395) +0.383 STGR(0. 060)

0. 831 20 2:146

ST1M=

s.d. =

+4. 868

(0. 327) +0.439 STMA(0. 077)

0. 850 16 2:146

ST1M=

s.d. =

+0. 580

(0. 579) +0.453 AUGR

(0. 043)

0. 707 66 2:146

ST1M=

s.d. =

+0. 655

(0. 685) +0.478 AUMA

(0. 053)

0. 754 40 2:146

ST5Y=

s.d. =

+1. 915

(0. 586) +0.577 WAGR

(0. 070) 0.783 34 2:146

ST6Y=

s.d. =

+2. 781

(0. 586) +0.388 WAMA(0. 067)

0. 854 17 2:146

ST5Ys.d. =

+4. 721

(0. 434) +0.219 STGR(0. 066)

0. 912 6.5 2:146

ST5Y =

s.d. =

+5. 392

(0. 358) +0. 181 STMA

(0. 085)

0. 932 2.3 2:146

ST5Y =

s.d. =

+1. 010

(0. 648) +0.381 AUGR

(0. 048) 0.790 32 2:146

ST5Y=

s.d. =

+0. 727

(0. 732) +0.422 AUMA

(0. 057) 0.806 28 2:146

ST28 -

s.d. =

+0. 992

(0. 322) +0.883 WETS

(0. 063)

0. 470 99 2:54

ST28 -

s.d. =

+0. 012

(0. 440) +0.723 DRYS

(0. 058)

0. 515 78 2:54

94
Table 8-33. Relationships of compressive strengths of the mortars of this series to those of the standard 1:2.76 {cement to Ottawa

sand) mortars of section 7—Continued

Equation

Dependent

variable Const. Independent

variable S.D. D.F.

33 ST1Y= +4. 959

(0. 463) +0.318 WETS

uyuj 0.676 6.2 2:54s.d. =

34 ST1Y= +4. 421

(0. 568) +0.285 DRYS(0. 075)

0. 666 7.3 2:54

s.d. =

35 ST1A= +1. 984

(0. 319) +0.687 WETS 0.466 61 2:54s.d. (0. 062)

36 S'I'l A +1. 132

(0. 404) +0.575 DRYS(0. 053)

0. 473 59 2:54

s.d. =

37 ST1M= +4. 725

(0. 474) +0.495 WETS(0. 092)

0. 692 14 2:54

s.d. =

38 ST1M= +3. 992

(0. 580) +0.430 DRYS

(0. 076) 0.680 16 2:54

s.d. —

39 ST5Y= +5. 160

(0. 486) +0.242 WETS(0. 094) 0.710 3.3 2:54s.d. =

40 ST5Y= +4. 794

(0. 603) +0.211 DRYS(0. 079)

0. 706 3.6 2:54

s.d. =

Table 8-34. Relationships of compressive strengths of the mortars of this series to the time of set of neat cements of normal consistency and the early compressive strengths of

the standard 1:2.75 {cement to Ottawa sand) mortars of section 7

Eq. No. Equation S.D. "P" D.F.

1 STGR =

s.d.= +7.941 -0.4037

(0.513) (0.1402) ISET 1. 114 4. 15 2:149 STGR=

s.d.= +6.920 -0.0658'

(0.689) (0.1039) FSET 1. 143 0. 20 2:149

3 STRG =

s.d.= +4. 443 +2. 087

(0.146) (0.137) STOl 0.715 116 2:149

4 STGR =

s.d.= +3. 760 +1. 261

(0.169) (0.074) ST03 0. 668 145 2:149

5 STGR=

s.d.= +3. 239 +0. 990

(0.190) (0.055) ST07 0.647 159 2:149

0 STMA=

s.d.= +5. 262 +0. 3125

(0.409) (0.1119) ISET 0. 889 3.90 2:149 STMA =

s.d.= +4.394 -0.0391*

(0.550) (0.0828) FSET 0. 912 0. 11 2:149

8 STMA=

s.d.= +2.414 +1.760

(0.105) (0.098) STOI 0. 514 160 2:149

9 STMA =

s.d.= +1. 739 +1. 109

(0.103) (0.045) ST03 0.405 304 2:149

10 STMA =

s.d.= +1.284 +0.869

(0.111) (0.333) ST07 0. 379 357 2:149

11 AUGR=

s.d.= +14. 18 -0. 201

(0. 62) (0. 170) ISET 1.349 0. 70 2:149

12 AUGR=

s.d.= +13.21 +0.038*

(0. 82) (0. 123) FSET 1.355 0. 05 2:149

13 AUGR =

s.d.=+n.57 +1.930

(0. 22) (0. 205) STOl 1.074 44.

1

2: 149

14 AUGR=

s.d.=+10.91 +1.180

(0. 26) (0. 115) ST03 1.039 52. 2 2:149

15 AUGR=

s.d.=+10.69 +0.842

(0. 31) (0. 094) ST07 1.091 40.5 2:149

IG AUMA=

s.d.= +11.94 +0.243

(0. 53) (0. 145) ISET 1. 150 1. 41 2:149

17 AUMA=

s.d.= +11.31 +0.229

(0. 69) (0, 104) FSET 1.143 2. 43 2:149

18 AUMA =

s.d.= +11.89 +0.954

(0. 22) (0. 208) STol 1.087 10.5 2:149

19 AUMA =

s.d.= +11.71 +0.514

(0. 28) (0. 122) ST03 1.098 S.9 2:149

20 AUMA=

s.d.= +11.67 +0.349

(0. 33) (0. 095) ST07 1. 112 6. 7 2:149

*Coef./s.d. ratio less than 1.

apparent relationship (eqs 11 and 16) between

the initial time-of-set values and the compressive

strength values of the autoclaved specimens

(AUGR, AUMA). There appeared to be no significant relationship between the time-of-final-set

values of the neat cements and the compressive

strength values obtained with any of the steam

curing procedures used.

6.7. Compressive Strength of Steam-Cured

Mortars Versus Early Strength of 1:2.75

(Cement to Sand) Water-Cured Mortars

The compressive strength values of the steamcured concretes are sometimes expressed as a percentage of the 28-day moist air-cured compressive strength and not in terms of the earlier strength values. Because of the limited quantities

of the cements available, it was not possible to make these tests on the mortars used in this series. Calculations were therefore made of the relationship to the compressive strength values of the

1 :2.75 (cement to sand) mortars of the previous

section of this series of papers (see previous

section)

.

The reduction in variance in equations calcul- lated for the relationships of STGR or STMA to the compressive strengths of the 1 :2.75 mortars

at one, three and seven days, eqs 3, 4, 5, 8, 9 and

10 (table 8-34), was highly significant. With highpressure-steam-cured specimens, AUGE. and

AUMA, the reduction in variance resulting in the

equations with 1, 3, and 7 day strengths was, in

all instances but one, eq 20, highly significant.

The numerical values were, however, much smaller

than those obtained in equations \vith the lowpressure-steam-cured specimens.

95
6.8. Linearity of Relationships

An hyperbolic relationship has been reported

for the relationship of the compressive strength

of accelerated cured concrete to that cured for 28

days under standard conditions [18]. The shapes of

the curves as well as the numerical values of the

coefficients and constants represented by the curves obtained by different investigators differ to some extent. Other investigators have expressed

their results as a linear relationship.

The calculations in this section of this series of

articles have been based on a linear relationship,

although it may be noted in figures 8-4 and 8-5

that there is appearance of nonlinearity. The use

of the hyperbolic relationship as in table 8-35

resulted in a lower S.D. value (numerically) for the STGR-WAGK relationship than was obtained in eq 2 of table 8-30, and for the STMAWAGR relationship in eq 3 of table 8-30. The

results for the high pressure-steamed cured compressive strength values, AUGR and AUMA

showed greater S.D. values than when a linear

relationship was assumed as in eqs 4 and 5 of table 8-30.

7. Summary and Conclusions

Table 8-35. Relationships of compressive strengths of mortar

cubes cured and tested under the conditions explained in the

text, and which were compared using an hyperbolic relation- ship

Values for compressive strengtlis are in 1000 psi units. (See p. 72).

Eq. No. Equation S.D.

1 STGR =+0.536 WAGR+0.0525 (WAGRXSTGR) 0. 424

s.d. = (0.026) (0. 0038)

2 STMA =+0. 273 WAGR+0.0684 (WAGRXSTMA) 0.295

s.d. = (0.015) (0. 0033)

3 AUGR=+1.638 WAGR+0.0139 (WAGRXAUGR) 1. 168

s.d. = (0.128) (0. 0093)

4 AUMA =+1.049 WAGR+0.0529 (WAGRXAUMA) 1.455

s.d. = (0.183) (0. 0141)

Determinations were made of the compressive

strengths of mortar cubes after steam-curing both

at atmospheric pressure and in an autoclave at 10 atm gage pressure. The steam curing was

started either 5 or 24 hr after molding. The

1 : 3.525 (cement to silica (including silica flour))

mortar cubes with a water cement ratio of 0.5 were made with 161 portland cements. Companion specimens were cured in moist air for 28

days, and some for only 14 days with a 14-day

drying period. In another series of tests on 65

Portland cements, the specimens were steamcured for 24 hr after 24 hr in moist storage. Half

of these were tested when still moist and the

remainder dried in laboratory air for 2 weeks

prior to making the compressive strength tests. The compressive strength values obtained after the different curing conditions were compared both

by statistical and graphic means. Equations were computed by least-squares methods to resolve

which of the commonly determined variables as well as the trace elements were associated with the

compressive-strength values of the different ce- ments after the different curing'and test conditions.

These tests on mortars, made using a constant

proportion of cement, sand, and silica flour with

a constant water-cement ratio, indicated that

(1) A considerable range of compressive strength

values were obtained for the different cements

after each of the curing conditions employed.

(2) There was an overlapping of the compressive

strength values obtained with the different types

of cement (as classified) with each of the curing

conditions.

(2.1) The type III cements were, in general, in

the upper area of the frequency distribution curves

for compressive strength.

(2.2) The cement classified as Types IV, V, had

low compressive strength values after the lowpressure-steam curing (STGR and STMA), but

had. fairly high values with autoclave curing after 24 hr at normal temperature (AUMA).

(2.3) The individual characteristics of the vari- ous Types I and II cements were such that no

general statement can be made relative to the

advantage of either type as classified.

(3) The frequency distribution curves (see fig

8-1) indicated a considerable overlapping of compressive strength values of the low-pressure-steamcured (STGR and STMA), and the moist-air-cured

mortars of different cements (WAGR).

(3.1) The low-pressure-steam-cured specimens

(STGR and STMA) had lower average compressive strength values than the 28 day moist-air

stored specimens (WAGR).

(3.2) The specimens which were air-dried after steam curing or moist curing had higher average

compressive strengths than when tested moist.

(3.3) The mortar used in the present series of tests resulted in higher 28 day compressive strength

values (WAGR) than were obtained at 28 days

(ST28) or 1 year (STlY) for the standard 1:2.75

(cement to graded Ottawa sand) mortar.

(3.4) The cements cured in high-pressure steam,

and then oven dried (AUGR and AUMA) had

the highest average compressive strength values.

(4) The relationship between strength, and the

chemical composition and the properties of the

cements, was affected by the different curing

conditions.

(4.1) For specimens cured with low-pressure

steam at 66 °C for 12 hr after a 5 hr presteaming

period, and then air-dried (STGR) an increase in C3S content and fineness and probably also the

C3A, SO3, and K2O contents of the cements were

associated with higher compressive strengths. In- creased values for loss on ignition, air content 1 :

mortar, (the air content of the mortar of the

present series used not being determined), Ba and

96

i
P in the cements were associated with lower compressive strength values. The variations of C3S,

fineness, and (air, 1 : 4 mortar) appeared to be

most significant.

(4.2) For the specimens cured with low pres- sure steam at 71 °C for 7.5 hr after a 24 hr pre- steaming period and tested when still moist

(STMA), increases in C3A, C3S, SO3, K2O, fineness,

and possibly Li were associated mth higher compressive strength values. Of these, the differences

of C3S and fineness appear to be the most signifi- cant. Increases in loss on ignition (air, 1 : 4 mortar)

,

and possibly Ba and Cu appear to be associated

mth lower compressive strength values.

(4.3) For specimens cured with high pressure

steam for 11 hr after a 5 hr presteaming period

and tested after oven drying (AUGR), increases

in C3A, C3S, C2S, SO3, fineness, and possibly Cr,

and Li were associated with higher compressive

strength values. Of these, differences in C3S, C2S

and fineness appear to be most significant. Increases in Na20, (air, 1 : 4 mortar) , and possibly

Ba and Cu were associated with lower compressive

strength values.

(4.4) Specimens autoclaved for 4 hr after they were 24 hr old (AUMA) had increased strength

with an increase in the C2S, SO3 and fineness of the cements used. An increase in Na^O, K2O, and

possibly insoluble residue, Rb and SrO were as- sociated with lower compressive strength values.

The (air, 1:4 mortar) was probably not significant

in equations for the NAE cements but the variable

i was probably significant when the air-entraining

cements were included.

(4.5) The compressive strengths of the mortars

made of the different cements, and cured after 5 and 24 hr with low-pressure steam, (STGR and

STMA) have a more highly significant relationI ship to strengths obtained under normal curing

conditions than do those cured in an autoclave

after 5 and 24 hr at normal temperatures (AUGR

and AUMA) . A laboratory test based on autoclave

treatment after 24 hr appears to be a poor indi- cator of strengths which may be obtained with

normal curing conditions.

(5) The equations calculated for the air-entraining plus non-air-entraining cements were

fairly consistent with those for only the non-airentraining cements.

(6) The use of the oxide composition instead

of the calculated compound composition resulted

in approximately the same estimated standard

deviations for the equations.

(7) The use of trace elements found to have

coef./s.d. ratios greater than one in the equations

in addition to regularly determined variables

usually resulted in a highly significant reduction

in variance. In general, none of the trace elements were highly significant, and, except for Ba and Cu,

did not appear consistently in the equations calculated for the compressive strength after the

various curing conditions.

(8) The estimated standard deviations computed

from the residuals in equations relating compressive strength to the independent variables were

larger than the estimated S.D. values for dupli- cate tests on different days. This appears to indicate that other variables, not considered in

the present study, may also have an effect on the

compressive strength values obtained with the

different cements after the different curing conditions.

(9) The effect on shrinkage or shrinkage-reduction, or on other important properties of steam-cured or autoclave-cured cement mortars were not determined, but these must be considered in commercial practice in addition to the

compressive strength as evaluated in this study.

In addition to many of the individuals mentioned in previous sections of this series of articles,

acknowledgements are made to R. H. Brookhyser

for additional chemical analyses, to D. Arnett, C.

Brubaker, C. Figha, E. Steward, V. Tyler, P. Worksman for preparing the specimens, and to other personnel for assisting in the work associated

with these tests.

8. References

[1]

[2]

[3]

[4]

[5]

[6]

[7]

[8]

ACT Committee 516 Report, High Pressure Steam

Curing: Modern Practice, and Properties of Autoclaved Products Proc. J. ACI 63, 869, (August

1965). R. J. Wig, NBS Tech. Paper No. 5 (1912). R. J. Wig and H. A. Davis, NBS Tech. Paper No. 47

(1915).

P. M. Woodworth, Proc. JACI 36 504 (1930).

J. C. Pearson and E. M. Brickett, Proc. JACI 38, 537, (1932). T. Thorvaldson, Symposium on the Chemistry of Cement, Stockholm, pub. by Ingeniorsvetenskapsakadien, (1938). Carl A. Menzel, Proc. JACI 31 No. 2, 125, (1934).

J. J. Shideler and W. H. Chamberlin, Proc. JACI 46, 273 (1949).

[9] R. W. Nurse, Magazine of Concrete Research (Lon

don) 1, 79, (1949).

[10] A. G. A. Saul, Magazine of Concrete Research (London) 3, 127 (1951).

[11] G. L. Kalousek, Proc. of the Third International Symposium on the Chemistry of Cement, London

(1952) Pub. by Cement and Concrete Association,

London.

[12] A. Aitken and H. F. Taylor, Chemistry of Cement,

Proc. of the Fourth International Symposium,

NBS Mon. 43, 285 (1960).

[13] R. H. Bogue, The Chemistry of Portland Cement,

2d Ed. (Reinhold Publishing Corp, 1955).

[14] F. M. Lea and C. H. Desch, The Chemistry of Ce- ment and Concrete, Revised Edition (Edward

Arnold Publishers Ltd., London, 1958)

.

97
[15] H. F. W. Taylor, The Chemistry of Cements (Academic Press, London and New York, 1964)

[16] ACI committee 517 Report, Low pressure steam cur- ing Proc J ACI 60, 953, (1963).

[17] J. W. H. King, Civil Engr. London 53, 881, (1957).

[18] T. N. W. Ackroyd, Min. Proc. Inst. Civ. Engrs. 19,

1, 1961.

[19] RILEM 31 June 1966 Articles by: R. Dutron, p. 167. W. Jarocki, p. 169. V. M. Malhotra, p. 177. V. M. Malhotra and N. G. Zoldners, p. 185.

N. Mihail, p. 193.

P. Smith and B. Chojnacki, p. 199.

J. Vuorinen, p. 205. H. Yokomichi and M. Hayashi, p. 209.

[20] R. L. Blaine, H. T. Arni, and B. E. Foster, Interrelations between cement and concrete properties. Part 1 Section 1 BSS 2. [21] R. L. Blaine, H. T. Arni, and R. A. Clevenger, ibid, Section 2. [22] R. L. Blaine, Leonard Bean, and Elizabeth K. Hubbard, ibid. Section 3. [23] Federal Test Method Standard, No. 158 Cements,

Hydraulic; Sampling, Inspection, and Testing.

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