6

NATBONAL BUREAU OF STANDARDS REPORT

6499

Drying Shrinkage of Concrete Masonry Units

Determined by Different Methods

by

J. 0. Bryson and D. Watstein

Report to

the Departments of

the Air Force, the Army, and the Navy

<NBS>

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
THE NATIONAL BUREAU OF STANDARDS

Functions and Activities

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maintenance of the national standards of measurement and the provision of means and methods

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Inquiries regarding the Bureau’s reports should be addressed to the Office of Technical Information, National Bureau of Standards. Washington 25, D. C.
3?©r! governffient

NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS REPORT

1001-12-10111 August 5 , 1959 6499

Drying Shrinkage of Concrete Masonry Units

Determined by Different Methods

by

J. 0. Bryson and D. Watstein

To

the Departments of

the Air Force, the Army and the Navy

NATIONAL BUREAU OF

intended for use yvithin t to additional evaluation a listing of this Report, eiti the Office of the Director, however, by the Governm

to reproduce additional c

IMPORTANT NOTICE

r progress accounting documents Approved for public release by the formally published it is subjected

Director of the National Institute of 1gl re P roduction - or open-literature c , , J j rp , . nission is obtained in writing from Standards and Technology (NIST) Such permission is not needed,

011 October 9, 2015. Ily prepared if that agency wishes

<NBS>

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
.

.

, *
Drying Shrinkage of Concrete Masonry Units

Determined by Different Methods

J„ 0, Bryson and D* Watstein

Four different procedures of measuring the drying shrinkage of concrete masonry units were compared in order to determine their suitability as possible standard test methods* The

four test procedures were the ACI Reference (73°F and 507o R*H„),

NBS Reference (73°F and 30% R*H*), Modified British (122' F and

17% R*H*), and Rapid (220°-235 ®F) * In addition to varying the

drying conditions, the size and shape of test specimens were

also varied* The specimens were whole block, face shells cut

in half lengthwise, thin laminas removed from the block at right

angles to the face shell, and "remnant" block remaining after

removal of the thin laminas*

The drying shrinkage tests were performed by all four procedures on both autoclaved and low-pressure steam cured block

of expanded slag, expanded shale, cinders, pumice, and sand and

gravel aggregates*

Considering the ACI Reference Method as a basis of comparison, both the NBS Reference and the Modified British Method

showed about the same extent of departure from the results on

the control specimens* The ratios of the NBS Reference results

to the control specimens ranged from 0*69 to 1*22, while for the

Modified British procedure these ratios ranged from 0*91 to 1*31*

For the Rapid Method, these ratios ranged from 1*22 to 3*35*

Considerable reduction in the time required for completion

of the shrinkage test at room temperature was achieved by the use

of thin section specimens developed at the NBS*

2 .

1. INTRODUCTION

The dimensional instability of concrete masonry units is a problem

of great concern for those connected with building construction. These

units, in addition to varying in length with temperature, undergo shrinkage due to drying. The degree to which a concrete masonry unit will

change in volume upon drying is known to depend primarily on the type of

aggregate used in the concrete and the method of curing it received.

Masonry walls constructed with concrete units that shrink excessively

often develop cracks that are unsightly and sometimes damaging.

Attempts to prevent the development of cracks in concrete masonry ^

walls by limiting the moisture content of the units at the time of con- struction have proven largely unsuccessful. There is at present a re- newed interest in the development of a rapid and reproducible test procedure to serve as a standard method for determining the drying shrinkage potential of concrete block in acceptance tests. This is evidenced

by the fact that two committees of the American Concrete Institute,

Committee 213 on Lightweight Aggregates and Committee 716 on High-Pressure

Steam Curing, have jointly sponsored a comparative study by four laboratories to determine the merits of different procedures for determination

of shrinkage. The National Bureau of Standards is one of the laboratories

participating in this study. The Bureau's participation in this study was supported as a subsidiary project of the Tri-Service Program.

2. SCOPE OF THE PROGRAM

The concrete masonry block used for the tests were units representing five different types of aggregate and both autoclave and low-pressure

steam curing methods. The aggregate types were expanded blast furnace

slag, expanded shale, sand and gravel, pumice, and cinders. In each case

the block were supplied by a commercial source which normally produce

them. All block were 8- by 8- by 16- in. units. Arrangements were made

to secure both autoclaved and low-pressure steam cured units from the same plant in order to have aggregates of the same quality in blocks

cured by both methods. Care was also taken to have the block delivered

in time to be placed under test when the block were 28 days old. However due to some inadvertent delays, some block were placed under test

about two to three weeks late.

Various types of specimens representing these block were placed

under test using four methods of drying. These were the ACI Reference,

NBS Reference, Modified British, and Rapid Methods of drying.
> . '
In addition to the shrinkage tests made on the units which were 28

days old, a second group of specimens were placed under test by the NBS

Reference Method after they were aged indoors for about four months

.

3. TEST PROCEDURES AND TEST SPECIMENS

All block were placed in a room controlled at a temperature of

73°F and 507, relative humidity for a minimum of 7 days prior to testing.

At the end of this period the necessary cutting was done and gage plugs were installed.

All specimens of the same aggregate-cure combination were placed

under test at the same time. The specimens were submerged in water at

73 ± 3°F for 48 hr prior to the test cycle, and the initial measurements

of length and weight were made immediately after the soaking period. A

Whittemore strain gage was used for measuring length changes over a 10- in.

gage length.

ACI Reference Method

The specimens were stored for drying in a room where the temperature

was controlled at 73 ± 3°F and the relative humidity was controlled at

50 ± 57o. The specimens were considered to be at equilibrium with the

drying conditions when their average change in length was not greater

than 0.0027> over a period of 14 days.

r i 1 /

Modified British Method [1]

Following the initial measurements , which in all cases were scheduled

to fall on a Friday,, the specimens for this method were placed in a room

controlled at 73 ± 3°F and 50 ± 570 relative humidity over a weekend, after

which they were placed in an oven in which the temperature was controlled

at 122 ± 2

C F and the humidity controlled by a saturated solution of calcium chloride. These conditions have been reported as providing a relative

humidity of about 1 7% [2j. The initial period of oven storage was 5 days.

This was followed by cooling over the weekend in air-tight drums. Length

measurements were made at the end of the cooling period. Subsequent drying periods of 48 hr followed by an overnight cooling period during the

week, and a cooling period over- the -week- end at the end of the week were continued until equilibrium was reached. The specimens were considered

to be at equilibrium when the average length change over a drying period

of 6 days (or three 48 hr drying periods) did not exceed 0„ 0027c.

JL/ The numerals in brackets refer to list of references at the end of

the report.
*

.

.
4,

Rapid Method

The specimens were dried in an oven in which the temperature was con trolled at 220°F to 235°F for 48 hr,, after which they were placed in airtight cooling drums located in a room controlled at 73 ± 3 F„ The

measurements were made on the specimens after they had cooled to the temperature of the room, Additional drying periods of 24 hr followed by

cooling in the drums were continued until equilibrium was reached. Equilibrium was considered to have been attained when the average change in

length during an oven drying period of 24 hr did not exceed 0,002%,

NBS Reference Method

The specimens were dried in a room in which the temperature was con- trolled at 73 ± 3®F and the relative humidity was controlled at 30 ± 2%,

Equilibrium was considered to have been attained when the average change

in length did not exceed 0,002%, over a 14 day period.

The test specimens used in this study are illustrated in figures

1 and 2, Whole block specimens illustrated in figure 2 were tested by

each of the four methods for each of the aggregate-cure combinations.

In addition to whole block specimens^ representative specimens were cut

and prepared for strain measurements. Two block of each aggregate-cure

type were prepared as shown in figure 1 for the ACT Reference and Modified British Methods, This figure shows the half shell and thin slice

specimens in the positions from which they were removed from the block.

It can be seen that four half shell and two thin slice specimens were obtained from a block. One thin slice and two diagonally opposite half

shells were tested by the ACI Reference Method and the remaining thin

slice and half shell specimens were tested by the Modified British Method

Accordingly, the specimens that represented an aggregate-cute combination

in the AC'I Reference and Modified British tests were two whole blocks two

thin slices,, and four half shells.

The specimens that were used in the tests of block of each aggregate

cure type by the NBS Reference Method were one whole block, one remnant

block ^ and two thin slices. Figure 2 shows the remnant and slice speci- mens outlined on a whole block, A view of the actual specimens prepared

for test by the NBS Reference Method are shown in figure 3,

< Test specimens for the Rapid Method were only whole block tested in

duplicate.

The location of gage plugs which received the points of the 10- in,

Whittemore gage are shown in figure 2 for the whole bloek ? remnant block

and thin sections. The location of these gage points on the half shells

is indicated in figure 1, It is noted that gage lines were established

both on the inner and outer faces of the half shells.
.
5.

The procedure used in fabricating the thin sections and placing them

under test is described here in considerable detail. It was observed

during the course of development of this specimen that it responded very

rapidly to changing environment during the period of fabrication. It was thought advisable to specify a standardized procedure to be followed in

the fabrication of the thin specimens in order to avoid certain irreversi

ble length changes which are known to have occurred in those thin section

which were permitted to dry partially during the fabrication period.

The thin slice specimens were cut using a 22- in, diamond cutting

wheel provided with depth and cross- feed controls. Diamond cutting

wheels,, of course, must be used with a liberal amount of water applied

as a jet at. the cutting edge. The slices were 1/2-in, thick. The cut

through a 8- by 8- by 16- in, unit is made in two passes of the diamond

cutting wheel.

After the first cut was made, holes for the Whittemore gage plugs

were drilled sufficiently deep to assure that the thin slice specimen is

perforated after the slice is removed by completion of the second cut.

The holes for the Whittemore gage reference plugs in the thin slices as well as in the remnants and whole blocks were drilled with a 1/4-in,

(#12) carbide tipped drill. The slice specimens were submerged in water

immediately after cutting. The slices were removed from the water one

at a time for installation of the plugs. As the gage plugs are installed

the specimens are completely covered with damp burlap and kept moist for

24 hours.

The reference holes in gage plugs were next drilled using a high

speed 1.2 mm drill. The specimens were removed from under the burlap

one: at a-' time and were placed in water immediately after the holes are

drilled., reamed and checked with a 10-in. Whittemore gage as being

satisfactory. The soaking period was reckoned from the time the speci- mens were returned to the water following processing of the gage plugs.

4. RESULTS AND DISCUSSION

The equilibrium shrinkage values for the specimens tested by each of

the four methods are given in table 1. These values are the averages for

the respective types of specimens and, with the exception of the values

determined by the Rapid Method are based on the shrinkage-time curves pre

sented in figures 4 through 8. The values of shrinkage obtained from

these curves correspond to the conditions of equilibrium previously defined.

6 ,

It is immediately apparent from the data shown in figures 4 through

8 that for autoclaved block the size of the specimen has no important

effect on the equilibrium value of shrinkage for a given test method.

The shrinkage-time curves obtained for the autoclaved block with three

types of specimens fall within a narrow band and in a random order for

all three test methods shown. However,, the average values of shrinkage

determined by the three methods showed measurable differences. It was noted that the British values were somewhat higher than either the ACI

Reference or NBS Reference values. When all the data obtained on the

autoclaved block are taken into account, it is seen that the ratios of

Modified British to ACI Reference values ranged from 1,08 to 1,29,

while the ratios of NBS Reference to ACT Reference values ranged from

0,78 to 1,07,

The relative standings of the values obtained with the whole block

specimens and the cut specimens were entirely different for low-pressure

steam cured block tested by the Modified British and ACI Reference Methods,

Without exception^ the thin laminas showed the greatest values of shrinkage , the half shell specimens showed intermediate values and the whole

block specimens showed the least values of shrinkage.

In general, the thin laminas also gave somewhat higher shrinkage

values when tested by the NBS Reference Method than either the remnant

or whole block specimens. However,, the differences observed between

the thin laminas and the parent remnant block in the NBS Reference

series were considerably smaller than the corresponding difference for

the ACI Reference series, Thus^, as can be seen from table 1, the

differences between equilibrium shrinkage values for the laminas and

half shell specimens ranged up to 0,01% in the ACI Reference series,

and to a maximum of 0,004% in the NBS Reference series. It is noted

that in making this comparison the half shell specimens and the remnant

block specimens are considered as comparable test specimens.

An examination of the time- shrinkage curves in figures 4 to 8 re- veals another important distinction between the results obtained by the

MBS Reference Method on one hand and both the Modified British and the

ACI Reference Methods on the other hand. In general, the low-pressure

steam cured block dried at 30% relative humidity (the NBS Reference

Method) exhibited a measurably lower rate of shrinkage as they approached

a state of equilibrium than did the block dried by either the Modified

British or the ACI Reference Methods, This fact is brought out graphically by the differences in the slopes of the curves near their ends.

The time- shrinkage curves of low-pressure steam-cured block of pumice^

cinders and expanded slag may be singled out in this respect. It is

also noted that for pumice block tested by the Modified British Method^

the criterion for equilibrium shrinkage was not met by the end of the

test after 23 days drying in the oven.

7 ,

The foregoing remarks concerning the differences in the rates of

shrinkage obtained by the three methods as the block approached equilibrium are not applicable to the autoclaved block , It is apparent

from an examination of these data that in general the slopes of the

shrinkage- time curves nearing the ends of the drying cycles were nearly

the same for both the ACI and NBS Reference Methods „ Only in case of

pumice block was there a significant departure from this observation;

the whole block and remnant block specimens in the NBS Reference series

showed a reversal in the shrinkage movement. It is significant that

the laminas cut from autoclaved pumice block did not exhibit such a reversal in the shrinkage movement, indicating that presence of significant amounts of moisture in the slower drying larger specimens was essential to produce such a reversal of shrinkage.

In view of the inconsistency of the effect of specimen size on shrinkage values, a comparison of the results for the different methods

was made using only the values obtained from whole block. Table 2 gives

the equilibrium shrinkage ratios for whole block specimens tested by

the Modified British, Rapid, and NBS Reference Methods using the results

from the ACI Reference tests as standard values. The shrinkage ratios

show that the Modified British and NBS Reference whole block specimens

shrink about the same amount as the whole block specimens tested by the

ACI Reference Method, The specimens from the Modified British tests

had shrinkage ratios for the different aggregate-cure combinations

ranging from a low of 0.91 for low-pressure cinder units to a high of

1.31 for autoclaved slag units, while the ratios for the NBS Reference

specimens ranged from 0,69 for autoclaved slag units to 1.22 for low

pressure sand and gravel units. The ratios for the specimens tested

by the Rapid Method show that drying shrinkage measured by this method

bore no consistent relationship to the values obtained by the ACI

Reference Method. For the low-pressure steam cured block the ratios

of Rapid to ACI Reference values ranged from 1,22 to 2.64; for autoclaved block, these ratios ranged from 2.12 to 3,33, It is obvious

that if the ACI Reference values for whole block specimens are to be

considered as being most nearly representative of the performance of

the block under actual service conditions, then the values obtained

by the Rapid Method cannot be relied upon for predicting the performance

of masonry in service.

It is generally assumed that, the equilibrium shrinkage values observed by the ACI Reference Method represent very nearly the maximum

values of shrinkage which the block develop at that temperature and

humidity. In order to verify this hypothesis, several low pressure

steam cured whole block specimens were permitted to dry for a prolonged

period following the attainment of equilibrium shrinkage values. The

results of these few tests are given in table 3. It can be seen that

the increases in the drying shrinkage during the additional drying

8 .

periods ranged from 9%, for pumice block to 35% for sand and gravel block.

It appears that shrinkage studies of concrete masonry units, particularly

the low pressure steam cured variety, should be carried out over considerably longer periods than were used in this study in order to arrive

at the "ultimate" shrinkage values.

The tendency for low-pressure cured block,, tested by the ACI Reference Method to continue to shrink for long periods of time may possibly

be explained by the fact that in addition to the drying shrinkage of

concrete, carbonation shrinkage also develops under favorable conditions.

Results reported by other investigators [3, 4j indicate that the conditions of drying used in the ACI Reference Method are conducive to car- bonation shrinkage. Verbeck [4] reported that carbonation shrinkage

was quite small at 30% relative humidity. This fact would seem to offer

an explanation of the significant differences in the behavior of the

specimens of various sizes in the ACI and NBS Reference series. The

relatively good concordance of the shrinkage values obtained with the

laminas, the parent remnant block, and the whole block specimens in the

NBS Reference series is a direct consequence of low carbonation shrinkage at a relative humidity of 30%,.

In order to determine the effect of prolonged storage on the shrinkage properties of block, a second group of specimens were tested by the

NBS Reference Method. The specimens were obtained from block that were

left over from the original source. The block had been stored in a room

for four months where there was no temperature or humidity control. The

shrinkage- time curves for this second group are presented in figure 9.

It can be seen that the shrinkage curves for the second group of autoclaved specimens were practically identical with those obtained from

the first group. However, the second group of low-pressure cured speci- mens had shrinkage equilibrium values that were reduced from 25 to 50%

compared with the shrinkage of similar specimens from the first test.

The results from this second test indicate that the shrinkage of lowpressure cured block is significantly reduced after several months of

indoor storage whereas the shrinkage of autoclaved block is apparently

unaffected by such storage.

The suitability of a drying shrinkage test procedure is also determined by the length of time required to attain equilibrium. The ages at

equilibrium for the Modified British, the ACI Reference, and the Rapid

Methods are shown in figures 10 and 11, while the data for the NBS

Reference Method are given in figure 12.

In. the ACI Reference Method the length of drying of whole block

specimens to equilibrium ranged from 31 to 85 days for low pressure

cured block, and from 28 to 36 for autoclaved block. The use of

laminas in the ACI Reference series did not produce a uniform reduction

in the time required to attain equilibrium. In four cases out of five,

9.

the use of laminas resulted in an appreciable reduction in the drying

time, for both low-pressure cured and autoclaved block,, In the other

two cases, the use of laminas increased the period of drying to equilibrium.

In the Modified British series, the length of drying of whole block

specimens to equilibrium ranged from 11 to 23 days for low-pressure

cured block and from 11 to 15 days for autoclaved block. The use of

half shells and laminas did not appreciably affect the length of drying

to equilibrium. The Modified British Method generally requires a much

shorter time for specimens to reach equilibrium than is required by

the ACI Reference. However, when the time required for cooling is

added to the oven drying time, as many as 40 days may be required to

reach equilibrium. This was the case for the pumice specimens (it is

noted that for every 4 days of oven drying there were approximately

3 days of cooling).

In the Rapid Method equilibrium was established in a much shorter

time than was required by any of the other methods. In no case was as much as a week of drying needed to bring about equilibrum. The average

number of drying days needed to meet the equilibrium requirement was 4,

and in only one case (low-pressure pumice) was as many as 6 days needed.

In the NBS Reference series, the time required for whole block and

remnant block specimens to attain equilibrium ranged from 24 to 42 days

for low-pressure cured block and 18 to 26 days for autoclaved block.

The use of laminas reduced the time required to: from 19 to 27 days for

low-pressure cured block and from 15 to 17 days for autoclaved block.

It is noted that the criterion, adopted for judging the attainment of

equilibrium in NBS Reference series calls for a 14 day period of observa

tions. In view of the fact that at 30% relative humidity both the lowpressure steam cured block and the autoclaved block exhibited a significantly lower rate of shrinkage as they approached equilibrium than at

507c relative humidity, it appears possible to accelerate the test by re- ducing the period for checking equilibrium to 7 days. If this were

done, the time required for the shrinkage test using the laminas would

be reduced to periods ranging from 12 to 20 days for low-pressure cured

block and from 8 to 10 days for autoclaved block.

5 . SUMMARY

1. The ACI Reference, Modified British, and NBS Reference Methods

produced roughly the same equilibrium shrinkage on whole block specimens

The ratios of Modified British to ACI Refetence values ranged from 0.91

to 1.31 while for NBS Reference series these ratios ranged from 0.69 to

1 . 22 .

10 .

2. The shrinkages obtained by the Rapid Method bore no consistent

relationship to the values obtained by ACI Reference Method, For the

low-pressure steam cured block the ratios of Rapid to ACI Reference

values ranged from 1,22 to 2.64; for autoclaved block these ratios ranged

from 2,12 to 3 , 15 ,

3. The size of the specimen had no important effect on the equilibrium values of shrinkage for autoclaved block tested by a given method.

However, the average values of shrinkage for the three types of speci- mens determined by each of the three methods in which the size of specimen was a variable,, showed measurable differences. With all specimens

taken into account, the ratios of Modified British to ACI Reference

values ranged from 1,08 to 1,29, while for NBS Reference Method these

ratios ranged from 0.78 to 1.07.

4. In the ACI Reference and Modified British series, the laminas

showed the greatest shrinkage, the half shells showed intermediate

values and whole block showed the least values of shrinkage. In general,

the thin laminas also gave somewhat higher shrinkage by the NBS Reference

Method than either the remnant or whole block specimens, but the differences were considerably smaller than the corresponding differences for

the ACI Reference series.

5. The rate of shrinkage of low-pressure steam cured block as they

approached equilibrium, was markedly lower when dried by the NBS Reference Method than for block dried by either Modified British or ACI

Reference Method. However, for autoclaved block the rate of shrinkage

as the block approached equilibrium was nearly the same for both ACI

and NBS Reference Methods.

6. The use of laminas did not produce a uniform reduction in the

time required to attain equilibrium by the ACI Reference Method. However, in the NBS Reference Method, the use of laminas reduced the time

to attain equilibrium significantly in all cases. In view of the fact

that it appears possible to shorten the period for checking equilibrium

in the NBS Reference Method from 14 to 7 days, the time required for the

shrinkage test by this method using laminas might be reduced to periods

ranging from 8 to 20 days.

7. Tests of a group of block by the NBS Reference Method after pro**

longed storage indoors indicate that shrinkage of low-pressure cured

block is significantly reduced, whereas shrinkage of autoclaved block is

apparently unaffected by such storage.

USCOMM-NBS-DC

REFERENCES

[1] Modified British Method of Test for Drying Shrinkage of Concrete

Products, Corps of Engineers Specification CRD-C73.

[2] Physical Properties of High-Pressure Steam-Cured Concrete Block.

Progress Report of ACI Committee 716, Proc. of the American Concrete Institute, Vol. 49, 1953, p. 745-756.

[3] Investigation of the Moisture-Volume Stability of Concrete Masonry

Units, J. J. Shideler, Portland Cement Association Bulletin D3,

Mardh 1955.

[4] Carbonation of Hydrated Portland Cement, G. J, Verbeck, Portland

Cement Association Bulletin 87, Feb. 1958.

Table

1.

Equilibrium

Shrinkage ud

a)od

<u

co

(U3i—I

ci3 > wd

CU • o os 00 CM CO CO OS o o X P* CM i-H r-H CM CM CM rH CM CM d • O o o O O o o o O o •H PS • • « • • • • • • • CJ o o o o o o o o o o

COd

0) . co MS MS' CM • <f

m l"n. X) Pm <0 in co m c • o o o o o o o o o O •H hJ CJ o o o o o o o o o o

0)o • CO I cn

•H Pa

m r-H 00 -d- <f- OS i-H CO

B • CO co co vt CO co rH CO <1" CO 3 PC o o o o o o rH o o o

CM o o o o o o o o o o

<L> CJ • nil CM | c •H CM 00 Os CO c O Os as MS o CM CO o P r\ 00 00 O 00 CO 00

•H 3 l-J o o o o o o CM o o o u CM o o o o o o o o o o

•H

1—11 E 01 . 00 as os o sD 00 sD o o X) > CM |—1

r-H r-H r-H 1—1

CM cn rH r-H CM

CJ

d

d . O o o o o o o o o o CO d pp

QJ us oo

O o o o o o o o o o d3

CJ1 i-H <D 0) . i-H : -U X) > CM co vD oo r-H r-H in 00 oo 00

ctf

d to . CM CM CM CM cn CO CM CM CM

00 CO

d 1-J o o O o o o o O o o 0) CO 00 • • d o o O o o o o O o o

00 <f (1) CM sO CO <f* 00 CM i-H 1—1

i-H • CM CM CM CM CM CM in CM CM CM 3 Cm O o o o O o o o o o pc • CO PS o o o o o o o o o o

0) in CO

m

m i-H CPs CM o CM

l“H • in so sO uo sO MS MS uo

m in

CO CM o o o o O

OO o o o

4=1 4 CO hJ o o o o O

OO o o o k

00 • cD ID in rH cn Os i-H CO CM

CO CM !—1 1 1 r-H CM rH i-H cn i—1

rH i-H

r-H • O o o o o o o o o o

co pc

O o o o o o o o o o *

00 • MS UO in 00 00 rH i-H co Pm m sO m in <1* in

r-H • O o o o o o o o o o

CO hJ o o o o o o o o o o d

CUU

B ctf CO

d

•H CU i-H

d CU i“l

d CU p>s CU Psi CO

d o 1—1 a 4H i—1

*rH r-H o 4H i-H •H id o i-H CJ

d •H

CU o o i-H CL)

B i o o rH CU

B o o o O

B

B

CM i n r-H CO pS CO rH ctf PS ctf Cl i-H i-H CU CO 3 PS PS co X 5 X X W X !3 rQ 5 X PS

X

T)rC

4J aDuasiajag qsi^xag pi dag aouasiaja^j

cU je IDV pajjipoiq saw

w

•H o X

rO (U rH d

CU

d > O

•H

a

d CU u d

CUcx CU CO 3

(U rH d CO> «\ CO CU 00 PS d H Hd3 „ o 00d B •H

cO >s

<U

d

4-J

X CO

M-i CU O d3 CO

co >s

CO CO

CU

X

da cn ! CM

PS

oo

d

•H •H PS U Xd

cO

dO

B

d

co

CU co •d cO

CO

CU CU d 00 3 cO

co P*J

co

d • CU •H CU d d OO

P- PS CO i CO JMX O 6 *H rd 3 d

•H PS

O

d CO

d

X•d IH

d id

O

0) •iH 4-1 3 CU CU cr 3 d QJ id o

CO CO • • d > 0) Pd d O 3 • CU 4-1 B id

PS

B 3 cO

•iH

d

B > X CJ O -H d <U •H K B cO Cd d CO 3

CO QJ

B

B e •d •H

Pd CU •H Q) x: • d d PS cfl i-S o CJ -d s # rH| CN| CO |

Table

2.

Shrinkage

ratios

for

whole

block

&ith

the

ACT

Reference

series

asa

base.

C/l u

CU o o LO LO

TO PH CN rH CTC C 0 0 © © EC rH CNl o o

C/l &H

cu 9—1

vO CN 0 <J\ CN o

(E Ph • ° •H t O rH rH o J

cuo o •H Ph rH

m LO

g CN CO rH 9 Ed o • • P4 rH CO rH

•* co cu •H o o CO CO

4J •H Ph o CD o

cd e 0 ©

©

© c p hJ pH CN rH

•H p-i rOeo rH u <u 0 CN CN cD

xs > Ph rH rH

O

a) c cd 0 ©

© « U cd 1-4 EC 1—1

CN rH

EJ CO bO O

a)

4-1 <nb 1“1

CO CU « CN cO CN

bO 'O > Ph CN] OC CN

CU c w 0 0 0 © u CO J-4 i-J rH rH rH

bO co bO $ a) rH O LTl LO

cO Ph o <t* o

r£ o ® co EC rH CN rH

<u CN LO

rH • o CN ac

CO Ph

©

© • ,C3 o r*H rH o

COJ - * - - •" ""

bO rH rH ac

CO PH CO CO cD

I—1 o ©

©

© CO EC rH CN o

hC o 00 CTc

cO PH CTn CN 00 « 1 c e 0 © CO 4-J o rH o

EE a) o

C/1 o 4—

*H

C

4-1 cu cu cu •H !h H o u

!h CU

O c d

CP 4H <3 cu cu CU cu Sh Eh PE o o cu cu

cu 4-* C3 4H 4H

•H t—1cu cu cu 4H o -a vj oE PE •H <3 •H CU

P-, <4-1 CO

H o O CO CU CP CJ S •U PE PE a <3

Table 3 „ Shrinkage observed beyond the equilibrium values as defined by the criterion for the ACI Reference Series.

, Aggregate f Cure

' Drying Increase in

Specimen" period [Shrinkage [Maximum-Maximum shrlnkage

type at equi- at "drying 'observed

librium ' equilibrium' period 'shrinkage

Slag L. Po

Whole

* » block

ays

50

1 percent

0.046

days

201

percent

0.058

beyond

equilibrium

percent

26

Sand &

gravel

* Pumice

L.P. ' Whole

1 block

L.P. » Whole »

» block «

I ? Cinders L.P, Whole ? f ? If block ? I ! !

31

85

70

0,023 178 ' 0.031

* 0.078 » 153 < 0.085

0 . 043 138 0.050

35

16

BR

Figure f Half shells and thin laminas shown in the positions

from which they were cut from block.

2

UJ2

o

UJ

CL

(f)

H2

<

2

2

UJ

£T

O

2

<

</> 2

UJ2 ^ — o O

O

_J

Ul

CL CD </>

UJ v' O °

$ o

? -J

55 CD o

FIGURE

2

RELATIONSHIP

OF

THE

THIN

L

AMINAS

AND

REMNANT

BLOCK

TO

THE

WHOLE

BLOCK

FOR

THE

NBS

REFERENCE

TEST.

1x1 <

O

Lxl o

:

o

o

<

2

<

o

2

hLsJ if) LU

OC

CL

LU

tr

CO

LU

O

LU

CL

if) <3

O

<

O

£

LU

>

roO

Ll

if) LU

LU

O

2

LU

tr

LU

lx

LU

QC

0)

GO

LU

ZC

fo

H

<

2

CD

O

O

LU

o:3

O

MODIFIED

BRITISH

METHOD

ACI

REFERENCE

METHOD

NBS

REFERENCE

METHOD

SC

•x.

o


 >

<

a

UJ2

H-O

>-oca

lN30H3d 30VMNIHHS 9NIAH0

FIG.

4

SHRINKAGE

VS

TIME

CURVES,

EXPANDED

SLAG

AGGREGATE

SPECIMENS.

MODIFIED

BRITISH

METHOD

ACI

REFERENCE

METHOD

NBS

REFERENCE

METHOD

lN39H3d 39VNNIBHS 9NIAH0

FIG. 5

SHRINKAGE

VS

TIME

CURVES

,

EXPANDED

SHALE

AGGREGATE

SPECIMENS

MODIFIED

BRITISH

METHOD

ACI

REFERENCE

METHOD

NBS

REFERENCE

METHOD

o

o

o

o

V)>

<Q

U

s

h- —

CDZ

>

Q

C

O

!N30d3d 39VMNIdHS 9NIAUQ

FIG.

6

SHRINKAGE

VS

TIME

CURVES,

SAND

&

GRAVEL

AGGREGATE

SPECIMENS

ooX

hUJo2

UJ

q:uj

u.UJ

<r

(n

coz oo

V)><Q

UJO2

>-OCa ooXX

</)

o:

coQ

UJoo

±N3DH3d 39VMNIdHS 9NIAdQ

FIG. 7

SHRINKAGE

VS

TIME

CURVES,

PUMICE

AGGREGATE

SPECIMENS

MODIFIED

BRITISH

METHOD

ACI

REFERENCE

METHOD

NBS

REFERENCE

METHOD * c/) ><Q

LUS

I-O2

>-ccQ

FIG. 8

SHRINKAGE

VS

TIME

CURVES,

CINDER

AGGREGATE

SPECIMENS

FIGURE

9

SHRINKAGE

VS

TIME

CURVES

FOR

THE

SECOND

GROUP

OF

SPECIMENS

TESTED

BY

THE

NBS

REFERENCE

METHOD.

(

THE

SECOND

GROUP

OF

SPECIMENS

WERE

AGED

INDOORS

FOR

4

MONTHS

BEFORE

TESTING)

PERIOD

OF

DRYING

TO

EQUILIBRIUM,

DAYS

80

70

60

50

40

30

20

10

0

— V) "o w

CD -cCO

<d to JSS

HS ° (7) L

m

ACI REFERENCE METHOD

m

Zx

m

m

W.

1yFi

SBG CINDER SLAG SHALE PUMICE

Note; I The period of drying to equilibrium for the ACI Reference specimens is defined os the drying time at the end of the first 14 day period

during which the shrinkage was 0.002%.

20

10

0

SBG CINDER SLAG SHALE PUMICE

Note: 2 The period of drying to equilibrium for the

Is defined as the drying time at the end of

during which the shrinkage was 0.002%.'

Modified British specimens

the first 6 day period

RAPID METHOD

n . n n n i i 1 SBG CINDER SLAG SHALE PUMICE

Note' 3 The period of drying to equilibrium for the Rapid specimens is defined as the drying time at the end of the first 24 hour period during

which the shrinkage was 0.002 %.

FIG. 10 ' PERIOD OF DRYING TO EQUILIBRIUM, HIGH PRESSURE

CURED CONCRETE BLOCKS.
.

- ;

.
PERIOD

OF

DRYING

TO

EQUILIBRIUM,

DAYS

FIG. 1 1 PERIOD OF DRYING TO EQUILIBRIUM , LOW PRESSURE CURED CONCRETE BLOCKS.

PERIOD

OF

DRYING

TO

EQUILIBRIUM,

DAYS

70

60

50

40

30 h

20

10 b

0

3 8

£> OD

CD ^c

0) a

Ely

to

O)

y\/V

LOW-PRESSURE CURED BLOCK

V V7Vy\y\mm

i,y\

y\

y\

y

\

y\zu

i

Expanded

Slag

Expanded

Shale

Sand 6

Gravel

Pumice Cinders

Expanded Expanded SandS Pumice Cinders

Slag Shale Gravel

Fig. S2 Period of drying to equilibrium for specimens tested by the NBS

Reference Method. ( The period of drying is defined as the drying

time at the end of the first 14 day period during which the

shrinkage change was 0.002 percent.)

U.s. DEPARTMENT OK COMMERCE

I'ra'ili'i ii'L II. Mueller. Se.-rclury NATIONAL llLIHlCAU OF STANDARDS

A. V. Amin, Director THE NATIONAL BUREAU OF STANDARDS

The scope of activities of the National Bureau of Standards at its headquarters in Washington, D.C., and its major

laboratories in Boulder, Colorado, is suggested in the following listing of the divisions and sections engaged in technical work. In general, each section carries out specialized research, development, and engineering in the

field indicated by its title. A brief description of the activities, and of the resultant publications, appears on the

inside of the front cover. WASHINGTON, D.C.

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