Fire Research Infonnatlon Services

National B^irpau of Stanoards

Bldg. 225, Rm. A46 ^

Washington, D.C. 20234

NATIONAL BUREAU OF STANDARDS REPORT

1817

FINAL REPORT

ON

INVESTIGATION ON AGCMIGATES AND CONCRETES

USED IN RIGID PAVEIJENTS SUBJECTED TO HIGH

AT© FLUCTUATING TEMPERATURES

by

W. L. Pcndcr^^act, R. A. Hcindl, C. R. Enoch, R. A. Clcvcn;gcr

<mp>

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
U. S. DEPARTMENT OF COMMERCE

Charles Sawyer, Secretary

THE NATIONAL BUREAU OF STANDARDS

The scope of activities of the National Bureau of Standards is suggested in the following

listing of the divisions and sections engaged in teehnical work. In general, each section is engaged in specialized research, development, and engineering in the field indicated by its

title. A brief description of the activities, and of the resultant reports and publications, appears on the inside of the back cover of this report.

1. Electricity. Resistance Measurements. Inductance and Capacitance. Electrical Instruments. Magnetic Measurements. Electrochemistry.

2. Optics and Metrology. Photometry and Colorimetry. Optical Instruments. Photographic Technology. Length. Gage.

3. Heat and Power. Temperature Measurements. Thermodynamics. Cryogenics. Engines and Lubrication. Engine Fuels.

4. Atomic and Radiation Physics. Spectroscopy. Radiometry. Mass Spectrometry.

Physical Electronics. Electron Physics. Atomic Physics. Neutron Measurements.

Nuclear Physics. Radioactivity. X-Rays. Betatron. Nucleonic Instrumentation.

Radiological Equipment. Atomic Energy Commission Instruments Branch.

5. Chemistry. Organic Coatings. Surface Chemistry. Organic Chemistry. Analytical

Chemistry. Inorganic Chemistry. Electrodeposition. Gas Chemistry. Physical Chemistry. Thermochemistry. Spectrochemistry. Pure Substances.

6. Mechanics. Sound. Mechanical Instruments. Aerodynamics. Engineering Mechanics. Hydraizlics. Mass. Capacity, Density, and Fluid Meters.

7. Organic and Fibrous Materials. Rubber. Textiles. Paper. Leather. Testing

and Specifications. Organic Plastics. Dental Research.

8. Metallurgy. Thermal Metallurgy. Chemical Metallurgy. Mechanical Metallurgy.

Corrosion.

9. Mineral Products. Porcelain and Pottery. Glass. Refractories. Enameled Metals.

Building Stone. Concreting Materials. Constitution and Microstructure. Chemistry

of Mineral Products.

10. Building Technology. Structural Engineering. Fire Protection. Heating and Air

Conditioning. Exterior and Interior Coverings. Codes and Specifications.

11. Applied Mathematics, Numerical Analysis. Computation. Statistical Engineering.

Machine Development.

12. Electronics. Engineering Electronics. Electron Tubes. Electronic Computers. Electronic Instrumentation.

13. Ordnance Development. Mechanical Research and Development. Electromechanical Fuzes. Technical Services. Missile Fuzing Research. Missile Fuzing Development.

Projectile Fuzes. Ordnance Components. Ordnance Tests. Ordnance Research.

14. Radio Propagation. Upper Atmosphere Research. Ionospheric Research. Regular

Propagation Services. Frequency Utihzation Research. Tropospheric Propagation

Research. High Frequency Standards. Microwave Standards.

15. MissUe Development. Missile Engineering. Missile Dynamics. Missile Intelligence.

Missile Instrumentation. Technical Services. Combustion.
NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS REPORT

0903-21-4428 June 30, 1952 1817

FINAL REPORT

ON

INVESTIGATION ON AGGREGATES AND CONCRETES

USED IN RIGID PAVEI.IENTS SUBJECTED TO HIGH

AND FLUCTUATING TEMPERATURES

by

Vif. L. Pendergast, R. A. Heindl, C. R. Enoch, R« A. Clevenge

Refractories Section

Mineral Proaucts Division

Sponsored by

U. S. Naval Civil Engineering Research and

Evaluation Laboratory, Construction battalion Center,

Port Hueneme, California.

NBS File No. 9,3/ll34C

The publication, n

unless permission I

25. D, C, Such F prepared If that

.NBS

Approved for public release by the „ p,„, „ Director of the National Institute of tandards, Washington Standards and Technology (NIST) ‘>een specifically on October 9, 2015.
/

;

>

vr.'-IC)’': a;

- ^

n > . i ?:> i;,

:

: r-"' !,; '‘-v

^

I

;'. . . •y.i.^;:

rV '^• )

I

I -J'-i

i Pl 'l « '.

I

* '>v v‘

^ -.. •* ;: ; n

" •. : ’ '

.: 'h'.'

' '/i , • . -
FINAL REPORT

June 30, 1952

INVESTIGATION ON AGGREGATES AND CONCRETES

USED IN RIGID PAVERiENTS SUBJECTED TO HIGH

AND FLUCTUATING TEI.IPERATURES

Technical Requirements

General; The objective of the project is the design

of heat-resisting concretes suitable for use in rigid

pavements for general ground circulation of jet-type

aircraft and especially for warm-up, power check, and takeoff operations of the aircraft.

Detail Requirements; The concretes must be of sufficient

strength to withstand loads to which they will be subjected.

Therefore, a minimum compressive strength of 2600 psi

is specified. The concretes must have a maximum resistance

to destruction when exposed to rapidly increasing and

fluctuating temperatures.
d:-

;

d •

i

/

s

i
- 2 -

I. INTRODUCTION

That phase of the project "Investigation of Aggregates

and Concretes Used in Rigid Pavements Subjected to High and

Fluctuating Temperatures," to be studied at the National

Bureau of Standards was discussed at a meeting during June,

1951, Dr, Herbert Insley, R. L, Blaine, R, A, Heindl, and

your Mr. Perry Petersen were present. It was concluded that

t such properties as refractoriness, thermal expansion, resistance to abrasion, heat transfer, compressive strength,

and modulus of elasticity should be determined. The

types of cements and aggregates that were to be used in

designing tho concretes were also selected at this time,

II . MATERIALS

The cements were (1) portland, a product of the North

American Cement Company, (2) Green Bag portland pozzolan,

a product of the Pittsburgh Coke and Chemical Company in

which the pozzolanic agent is a blast furnace slag, and

(3) Lumnite, a high-alumina hydraulic cement, manufactured

by the Universal Atlas Cement Company.
\

y-'

,‘V'- 't'i-r'- ’'

-.1

'

V

' “ •;.)

•

* -V-

,{

'\ >

' ; i' ':%

j '5^^

!-i ./i '

i'j;

'

, i

r
- 3 -

Twelve aggregates were selected on the basis of both

availability and possible suitability. Five of this group

were classified as light weight aggregates and the other

seven as more refractory and of a non-light weight classification. The light-weight group included two expanded

shales "Lelite" and "Haydite," a clay-coated expanaed shale

"Rocklite," an expanded slag "Vs/aylite," and a pumice from

California, The non- light weight group included an olivine

(an iron-magnesium silicate from North Carolina), "Bluestone"

(a limestone from Western Maryland), a medium dense common

building brick, a portland cement clinker, gravel and sand

known as "White Marsh," and a Kentucky flint clay. The

flint clay, which contained considerable iron pyrites and

therefore unsuitable for firebrick manufacture, was submitted

in two lots. One lot was received in the green state, that

is as mined, the second had been calcined at about 1250“C.

A detailed description of the light weight aggregates

was given in a publication by the Housing and Home Finance

Agency ,-i/

4 -

III. iVlETHODt) OF PxHi.PARATIOW AND TESTING

A, Refractoriness . The pyrometric cone equivalent^/ or

refractoriness of the cements, a^^gregates, and concretes

was determined in a gas-heated furnace except the calcined

flint clay. A carbon resistence furnace was used for this

de termination,

1, Cements . The portland and Portland pozzolan cements

were tested*::* in accordance with Federal specifications

SS-C-192, Type I, and SS-C-208a, respectively. There are

no Federal Specifications for hydraulic cements of the

high-alwaina type. Lumnite cement, therefore, was tested

in accordance with sS-C-192, Type III.

2, Aggregates . The crushing strength of the aggregates

was determined by employing the methods described in a

Bureau of Reclamation publication.—/ All other tests, with

slight modifications necessitated by the characteristics

of the material, \\iere conducted in accordance with the

methods described in the "1950 ASTn Standards on Mineral

Aggregates, Concrete, and Nonbi tuminous Highway Materials,"

3, Concretes . The data on aggregate sizing and the

cement-aggregate ratio given in the publication,i/ issued

by the Housing and Home i^'inance Agency, was used to advantage

Made by the Mineral Products Division, Concreting Materials

Section, National Bureau of Standards,

- 5 -

in designing the concretes. The mixes were adjusted to

compensate for differences existing between sizes of the

aggregates used in this study and those listea in that

publication. The concretes were proportioned by volume

and mixed in a three cubic foot tilt-drum mixer. The

water and aggregate were mixed for one minute, the cement

and an air-entraining agent, vinsol resin, were then added

in that order, and the complete batch mixed for an additional

three minutes. The concrete was then placed in specimen

molds and the surface finished immediately with a wood

float. Each batch contained sufficient concrete for the

following specimens: four 6 x 12 inch cylinders, two

3 X 4 X 16 inch prisms, one 24 x 24 x 2 l/2 inch slab,

and two 8 x 8 x 1 1/4 inch plates. The 24-inch slab, after

partial set, received an additional delayed finishing with

a steel trowel. All specimens were covered with wet burlap

until the end of a 24-hour period. They were then removed

from the molds, cin*ed for six days in a fog-room and stored

at laboratory temperature and humidity for 21 days. Because

it was planned to test each concrete after curing, and also

after five different heat treatments, limitations of

laboratory facilities made it necessary to fabricate separate

lots of specimens of each concrete on subsequent days.
m
/

- 6 - Specimens of each concrete were tested after a curing

period of 28 days and also after each of the following heat

treatments; 250, 500, 750, and 1000°C respectively. The

temperature of the kiln in which the specimens were heattreated was increased approximately 50° C per hoiu? to the

maximum scheduled temperature. After temperature equilibrium

was reached, throughout the specimens the kiln was held at

the maximum temperature for five hours. The specimens

were cooled in the kiln to room temperature.

Fifteen concretes were designed ana tested using

Portland, Green Bag, and Lumnite cement, respectively, with

each of five aggregates, namely pumice. Haydite, Vi/aylite,

Rocklite, and Lelite.

The linear thermal expansion will be determined of

concrete specimens to the maximum possible temperature

depending on their refractoriness. For this purpose

specimens have been prepared measuring 1x1 l/2 x 7 l/2

inches

.

Measurements of the thermal conductivity of the concretes were made-::- using the hot-plate apparatus shown in

Figure 1, It consists of an electrically heated hot-plate

8 inches square, set in a horizontal plane, and a cold plate

of the same size cooled by n-pentane (G 5H12 ) boiling at

atmospheric pressure (i.e,, at approximately 98 °F).

Thermal conductivity measurements were made by the Exiilding

Technology division. Heating and Air Condi ti'^ning Bection

of the National Bureau of .standards.

FIG. I -Hot plate thermal

conductivity tester

- 7 -

The pentane vapor was condensed in an air-cooled condenser

arranged so that the condensate returned to the cold plate.

The test specimen, 8 inches square and approximately

one inch thick, was placed between the hot and cold plates.

The contacting surfaces of the plates and of the specimens

were ground flat to assure good thermal contact between

them. Copper-constantan thermocouples were set in the

surfaces of the hot and cold plates to measure their

temperatures. Heat flow dovmvjard and outward from the

edges of the hot-plate vtfas made substantially zero by means

of an electrically-heatea copper guaro pan placed under and

around the hot-plate with insulation betvi/een them, by

adjusting the guara to the same temperature as the underside

of the hot-plate, as indicated by the thermocouples attached

thereon.

The tests were conaucted with the hot-plate at about

140 °P and the cold plate at about 98 "F. When steady

temperatures were attained v^ith the guard properly adjusted,

the electrical power input to the hot-plate and the

temperatures of the hot and cold plate surfaces in contact

vifith the specimen were measured. The thermal conductivity

(k) of the specimen, expressed in Btu per hour per square

foot per degree P per inch temperature gradient, was

calculated from these data combined with measurements of the

area and thickness of the specimen.
ii' 'V/S
8

The test apparatus v;as checked by a series of comparison

tests made in the bureau’s g^uarded hot-plate conauctivity

apparatus, conforming to AbTlvi C-177, on a specimen having a conauctivity of 0.8. Agreement between the tests in the

two sets of apparatus was within 1,1 percent.

The cast specimens were prepared with flat and parallel

faces by grinding, and were aried in a ventilated oven at

220°F for 72 hours prior to test. The duration of a test

vms from 7 to 24 hours, aepending upon the time necessary

to attain steady temperature conditions. The specimen was

weighed immediately before and after test.

The resistance of the concretes to abrasion was deter4/ mined using the apparatus designed by bchuman and Tucker,—'

The compressive strength of the concretes was determined

5 /

in accordance with AbTi.i iuethod resignation C3S-44,—

Young's modulus of elasticity was determined in accord6

y ance with the method described by Gerald Pickett,—'

Other properties and pertinent data relating to the

concretes were determined as follows. The proportion, by

weight, of cement to coarse to fine aggregate was arrived

at using available information on concretes designed with

similar aggregates. The same procedure was followed in

determining the amount of vinsol resin to be added.

The cement content, air content, and weight of fresh

concrete was determined according to AGTlvl Designation

0138-44.-'^

The water content Wo.s calculated by the following

formula:

water Volume of concrete yielded in cubic yards

The slump of the fresh concrete was determined according to ASTIvl Designation 0143-39.-^

The weight per cubic foot of concrete after curing or

after heat- treatment was calculated by the formula:

Vileight per cubic pounds

Volume in cubic feet

The strength-weight ratio was calculated using the

formula:

strength-weight

'The linear shrinkage, based on the inner dimension of

the mold, was calculated using the formula:

Linear shrinkage =

x

100

where

:

lo = original length

If = final length

IV. RESULTS AND DISCUSSION

Refractoriness or Pyrometric Cone Equivalent . Table 1 gives the pyrometric cone equivalent (PCE)

of the cements, aggregates, and concretes. Although portland cement is appreciably more refractory than the highalumina cement, PCE of 18 versus 14, nevertheless, it is

not considered satisfactory for use in heat-resis tent

concrete. The reason for this fact is that portland

- 10

cement, after dehydration and heating may form be ta-dicalci\im

silicate which in turn will convert to gamma-di calcium

silicate. Such an inversion is attended by a marked volume

change causing the product to "dust," which in turn results

in a marked loss in bonding strength. Inasmuch as silica

is a minor constituent of Lumnite there is an insignificant

amount (if any) of dicalcium silicate formed and consequently

in this cement no "dusting" occurs. The tests indicate a

wide range of refractoriness in aggregates, namely. Gone 2

for pumice and Kocklite to Cone 31 for flint clay. The

results of the PCE determination of the concretes indicate

that the substitution of Lumnite cement for either portland

or Portland pozzolan increased the refractoriness of all

concretes except that containing yaylite. The concretes

designed using pumice as an aggregate showed aefinite

indication of fusion at 1000°C. However, when Rocklite,

the other aggregate with a low PCE was used, there was no

indication of fusion at lOOCC.
. •'1 ,

•

. .-vyV^ :€:;;yiip^

' fW
11

Table 1

Pyrometric Cone Equivalents (PCE)

of

Cements, Aggregates, and Concretes

Cement Aggregate Cement

Aggregate

•ratio

by weight

PCE Equivalent

approximate

temperature

(^C)

Portland 18 1490

Portland pozzolan — - - - 14 1400

Lumnite ” — — “ ~ 14-15 1420

Pumice ... 2 1165 — Rocklite — 2 1165 — Haydite — 6 1230 — Le li te — 10 1305 — Vi/aylite — 13 1350 — Common

- building

brick — 15-16 1450 — Flint clay

calcined “ 31 1680

Portland and Pumi ce 1 : 1.5 5 1205

do do Rockli te 1 : 3.9 4 1190

do do Haydite 1 : 3.6 4 1190

do do Waylite 1 : 2.4 14-15 1420

Portland pozzolan and Pumice 1 ; 1.5 4 1190

do do Rockli te 1 : 3.9 4 1190

do do Haydite 1 ; 3.6 3-4 1180

do do V\/ayli te 1 : 2.4 14 1400

Lumnite and Pumice 1 : 1.5 7-8 1255

do do Rocklite 1 : 3.9 5-6 1220

do do Haydite 1 : 3.6 9 1285

do do Waylite 1 ; 2.4 12 1335
‘ " f ,''7

'a

1, i .'f' s jW

« >

'

. > •• ’T i. r m

?• '. V?’ '* *

. j , •- \ .•-?«« •,-* • , -^ S

' "

s>r

' ' ; <• ,

. ... ,. '. ..,.„ -J'/r

/'A

' :

. * PX '/Mi'A*

<^i'^:r^

'ti

.

, ,., ,

, ,......, .

^C'litwW- ''

V - '.-i-4

’

.

^mu ' ZpU

' .,

' -i, ','V ,;^ 1

'

i'C'

\J

oa-:!:

' k: J / ' I. . s«i 1.' IfTi. *\' •* i t'fl. k

' I' '

>^

4,

- mJ: ;^. ; i

O&P-:. ;,, '’a.r-.ai.

3

'.'"^?^'' v[ '.'':v%

An^.r’, /yV . .>‘ - r>

,*’ ... .^. }J/'>i J .',!

5. SO X

Wv-»'iP*».«» V*' -lEI <M •

.

;,' >.^'^<>ji». J«. .

'

, 'V ., '^ k'C* . V V .Viij.^ .

'. “s' ^

r.yfi

' MArf W,.

V/C,v«> 4*-

• VW*. MlWiin'rCdik

; :./; /;;.v; ^>5 ._^ i>iivVs;.v'’A

"

',fi'V'-..

t-;, , > :" V

m.i'w

aa^T , -y -: P V* i-

’ cy -•vd ,

.

. . ,-<W

. V* •^*'.

•' r. .

'.'

.

' .

f -

^''. 1.

u

• ^'.. a!; ox. . ;'^ ’iA.i

’’\- • ^ '

'<^ ; '-

-V'.

' ' T ... .:^,

.

'•

’.' -'

1 •\ . 'rvt* 4 «•.I4.-W «*i<»4i^«*»l. . IVSv. .,'•

. .• 4*4<* Ml i,*-4 .„'.

* ' .'

'

. . 2s?'r'

.' w. .

' t

','v;'; 1'

-, _,l. *' :'i.':.4x..:; '' •

', ,:Sv ^,,i'':‘"'.

t’V
12 -

1. Cements . The results of the physical tests and

chemical analyses are given in tables 2 and 3.

Table 2. Results of physical Tests of Cements

Cement Time of

Initial

set

Final

Surface

Blaine ^

apparatus

Compressive Strength Air

3-day 7-day 28-day

iGIlw

Autoclave

Expansion

Hr. Min, Hr. Min.. cm2g lb/in2 Ib/in^ lb/in.2 % %

Portland 4 : 40 7 : 00 3340 1040 2040 3820 8.0 0,10

Portland

pozzolan 4 : 45 7 : 05 3770 1170 1780 3370 13.2 0.02

High - alumina 11 : 30 13 : 15 4280 4360 5200 5.4 0.02

Table 3. Chemical -bialysis of Cements

Cement Ignition

Loss

Insol.

Residue

SO3 Si02 AI2O

3 CaO MgO Total

alkali

as Na20

K2O FeO

% % % % % % % % % %

Portland ^ 1.9 0.2 1.7 21.6 5.7 2.6 62.4 3.1 0.30 0.84

Portland

pozzolan 0.0 0.3 1.7 24.7 7.7 2.2 59.4 1.8 0.05 0.44 2.0

Highalumina -0.1 s/ 1.7 0.3 8.6 42.7 4.3 36.8 0.8 — — 6.2

^ Tentative method of Test for Fineness of Portland Cement by Air

Pemeability Apparatus A.S.T.M. Designation: C204-46T, 1946

±1 Gain
r

)

f '!

i

(

A c- .,.-

V: >} . « •

J: . ->

'

'
- 13 -

The Portland cement complied with the technical

requirements of Federal Specification SS-C-191, The

Portland pozzolan, however, failed to comply with the

required compressive strength (1800 psi) after seven-day

aging.

The outstanding difference in the chemical compositions

of the three cements is that Lumnite contains a much higher

percentage of alumina and considerably less calcium oxide

and silica.

The setting of portland cement is due to the formation

of hydrated calcium silicate. Because Lumnite contains

only small amounts, if any, of the silicates its setting

is the result of the formation of hydrated calcium

alumina tes and hydrated alumina, Bince the alumina tes

hydrate more rapidly than the silicates, a high-alumina

cement, such as Lumnite develops a high early strength

as indicated in table 2.

2c Aggregates , Table 4 gives the screen analysis

and some properties of the aggregates. This information

aided in the designing of the concretes. Two general sizings

of aggregates vifere used in each concrete. One of these

sizings designated as “coarse'* consisted primarily of

material retained on a No, 4 and passing a one inch screen.

The other designated as "fines" consisted of material

passing a 3/8 inch screen.

i ific 1 ity . J

, Diy

i Water

j Crushing strength Ibs/in^

[ Absorption <

1 Percent by

weight

Compaction, inches

1 2 3

74

64

0 *24

1,06

(f) —

66

08

n<,28

8.61

1,535 13,363 41,062

65

09

8.42

5.50

561 3,244 39,824

I

to

to

0

<X\ 17.10

2.61

264 943

i 8,450

1 26

43

39.00

Aii-.SO

396 1,563 6,/i65

32

65

81

10.54

10.22

17.80

2,780^®^ 28,299^®^ 41,026^®^

97 17.10

1

I

26

27

37

S.93

1 9.60

I 6.10

1

1

— —

65

65

1 0.90

1 0.80 1 3,930

1

(f)

41,030 —

52

50

4a76

5.03

770 13,074 40,682

97 1 3o20 " TM — —

1
.t '-•

.

1 ^

Cru\. 'fi*.-? l:i

- V

• ' ‘

. ys «.

' r 'v-'

- '-s -Vr '^' aL

:;.‘ .\ " V'i;

' ''

"> -.IV '< 't-- - f*

' i" .* ^>t . \ t- • ij ;.••’ •• • *•< *"'•< * : '. i' V’/-'- . Vff 3 , ,'i.X.,

'vt- • ••>:

A

ir AN

a*

' '

_

' _

’ :

' ;

'" ’' '’ ‘'

;

-

' -'V

•'i^y y 'yi<

y-' : -,;- y ;A

'

'

'

'

'

'"'

'

'''

it *, ' ,'f

W. V .*

.

•• ’ ,-•* ‘ .• / V'. j

'

' i ; /;’ .V

)P^.

?. C If

: u-Ky..^.,

' ''

'' ' - j.'lli'.i i ,^’r '

/. ''•,"; A' : - . ,,y; •

vUy-' y:. *: ; *yy.iyi;iiy-y, /' y yyv';-''^;' 'y/yyiyitiryb. ; ,yj y ;.

;•> v'r

,r<,y.;y>yy >;/v,:; ,y .>.^yne

/ ; >;y!,

;

'y -y'”--

yyy.^iy;

i;o

" - ;".• •'' -y ii'4 ^:;”t.y,

,.''/»r'V'''

v:-myrl«> , 'i-.u >H&‘y .y.../*

-,,.y ^AUm ^

' ', -^'V^

s';-

''

,.

-• ''vwy..'."'.: •

.

• '>$

'' -y,: .'y-

'sVrf^'; i .c.'fi' ij ijy ; • y, i,;. y y-y '

. X-g

. . , , .ry: ,. :

.,

,- . yh;y-.^

•^t'y
Tabic 4. Properties of Acgregates

I^aterials Sieve Analysis

Fineness

Modtilus^^^

Unit Weight

lbs/ft3 Bulk

Specific

Gravity

S.S. Dry

-y

n,,,.!,-! ... 9 (A\

Identifica- Size

Amoxmt passing U. S. Standard Sieve, percent bv •./eiglit

.ifaLtor XDS/iji

1 Jigged

'

tion

Nos.

Loose 1

I Percent by

1" 3/4" 1/2" 3/8" 4 8 16 30 50 100 200

weiglit

1 2 3

Bluestone Coarse

Fine

100.0 99.1 71.6 22.7

100.0

3.1

99.3

2.0

79.6 50.7 26.7 11.5 3.7 11.3

6.73

3.28

83.6

99.8

98.0

113.0

2.74

2.64

0.24

1.06

(f)

Haydite Coarse

Fine

100.0 95.3 71.1

100.0

11.1

99.8

1.8

95.3 70.7 43.5 27.4 18.3 12.6

6.16

2.45

53.8

68.1

62.1

97.5

1.66

2,08

11.28

8.61

1,535 13,863 U,062(^)

Lelite Coarse

Fine

99.9 97.9 75.5 40.3 8.5

100.0

6.8

97.3 68.0 42.7 26.6 16.8 10.8

6.J+6

2.48

42.4

63.9

47.9

73.1

1.65

2.09

8.42

5.50

561 3,244 39,824^^^

Waylite Coarse

Fine — — 100.0 94.2

100.0

16.8

99.9

8.8

97.3 84.6 54.9 32.0 15.2 5.9

5.80

2.16

33.2

60.4

39.4

72.2

1.68

2.38

17.10

2.61

264 943 8,450

Pumice Coarse

Fine

100.0 98.7 82.5 51.0

100.0

16.8

76.3

15.4

46.2 32.8 21.8 34.3 8.1 13.5

6.18

4.01

29.2

38.6

32.1

43.9

1.26

1.43

39.00

396 1,563 6,465

Roclcllte Coarse

Tliru 9/16

Thru 5/16

Fine

100.0 78.9

100.0 98.9 59.9

100.0

100.0

0.7

44.5

99.8

1.3

78.7 40.0 20.6 9.5 3,9

—

7.21

6.39

5.54

3.48

47.7

51.3

55.3

66.3

52.0

57.0

61.9

13.3

1.32

1.65

1.81

1.97

10.54

10.22

17.80

17.10

2,780^®^ 28,299^®^ 41,026^°^

Building

Brick Coarse

Medium

Fine

100.0 99.1 66.8

100.0

15.2

98.3

100.0

4.4

16.5

99.9

3.9

5.4

70.9

4.3

50.5 36.0 23.5 11.0 7.5

6.77

5.75

3.08

61.4

60.5

80.1

71.9

70.3

91.9

2.26

2.27

2.37

8.93

9.60

6.10

— — —

Flint-clay

Calcined

Coarse

Fine

100.0 99.6 85.3 70.4

100.0

44.2

75.1

24.9

38.0 20.2 10.6 5.2 1.8 0.9

5.60

4.49

87.7

89.4

101.7

101.3

2 .65

2.65

0.90

0.30

3,930 41,030 —

Flint-clay

llaw

Coarse

Fine

100.0 99.8 83.2 69.8

100.0

45.5

76.3

29.3

37.3 20.1 10.2 4.6 1.5 1.9

5.55

4.50

86.0

80.9

101.5

95.0

2.52

2.50

4.76

5.03

770 13,074 40,682

Olivine I Coarse

Fine — 100.0 85.3 70.9

100.0

54.3

99.9

45.6

99.3 82.0 65.5 35.2 10.3 4.0

5.29

2.08

124.8

114.4

146.7

130.5

2.97

3.09

3.20

1.00

• —

:: —

IVnite Marsh

Gravel ( Sand 1

/oarse

ine

89.9 76.2 54.1 31.9

100.0

3.3

97.9 8.00 64.9 49.5 22.0 4.1 1.2

6.88

2.82

101.1

100.4

110.9

112.0

2.64

2.63

0.30

0.30

--

— — —

(a) Indicates distribution of sizes of aggregate as detemined by ASTM method C125-43 "Standard Definitions of Terms Relating to Concrete and Concrete Aggregates", ASTIi Standards on Jincral Aggregates, Concrete, and

Nonbituminous Highway Materials, Sept. 1948, page 70.

(b) Indicates bulking or fitting together of various sizes of aggregates . (c) "S.S." Saturated aggregate - Surface Dry.

(d) Grading — 505^ through 3/8" retained on No. 4; 30% through No. 4 retained on No. 8; 2£t% through No. 8 retained on No. 16.

(e) Rocklite — 60^ through No. 4 retained oh No. 8j througli No. 8 retained on No. 16.

(f) Bluestone beyond capacity of apparatus at 1" compaction;

Flint clay (calcined) maxinium compaction possible with apparatus 1 13/16"

Haydite " ti n u u 2 21/64"

Lelite " n n 11 "2 23/64"

Flint Clay (Raw) " " " n n 2 9/l6"

- 14 -

The screen analyses were necessary to determine the

distribution of the particle sizes. Prom these analyses

the fineness moduli of both the "fines” and the coarse were

calculated. The modulus of the "fines" should not exceed

a value of approximately 3,2. The fineness modulus of the

combined mixture of fine and coarse aggregate is calculated

in accordance v^/ith the respective proportions of each used

in the concrete mix. It is not considered desirable that

this value exceed approximately 5,2. Two of the fineness

moduli of the "fines" as given in table 4, were above the

limit of 3.2 and the combined fineness moduli of the same two

aggregates were slightly above 5,2. This data refers only

to the five light-weight aggregates reported. Values outside

these limits tend to develop a harsh concrete vi/ith a high

percentage of voids, resulting in a loss of strength.

It must be recognized that the fineness modulus does not

apply perfectly to light-v^eight aggregates since it was

founded on data using normal aggregates. The bulk specific

gravity factor adjusts the mix to the proper proportion, by

weight, as compared to volurae. The water absorption of the

aggregate determines the amount of excess mixing water to add

to the cement-water ratio. The crushing strength in compaction indicates the maximum strength obtainable with that

aggregate. The strength of the resulting concrete, hovi/ever,

also depends on the shape and condition of the surface of

the aggregate.

iulus

city

igitudinal

After

heating

Linear Shrinkage Abrasion

Before After Loss

heating heating

X 10^ % % gms

—I — — — —

— — — —

— — MM MM , 0.000 0.766 —

— 0.050 4.990 —

- ' —*« MM MM — •— 0.650 — — — — MM — 0.067 0.916 —

0.130 2.210 —

—

.

0.116

— — — —

— — — M. — 0.083 — —

— 0.170 — —

MM . MM

1.373 0.083 0.216

1.360 0.110 0.180 A4.3

0 .560 0.000 0.450 625.5

0.527 0.217 -0.166 — 0.100 — —

MM MM MM

1.160 0.166 0.216 —

0.922 0.060 0.190 50,0

0.59/* 0.100 0.430 338.4

0 .434 0.317 -0.183

I

ncrete mixes of the

»rirll show any

Tablo 5* Properties of Heat-Resisting Concretes

Laboratory

IdentifiProportions Vii^sol

by weiglit Cement Content resii\ by

Cement to x^iglit of coarse and to cement

fine aggregate

Water Content Air

Content

Slump

on fresh

concrete

Weight

of fresh

cone rete

Weight of Concrete

after

7-day Heat treat-/

21-day R. T, ment ^

Compreesivo

Strength

6 X 12 in,

cylinder

Strength

weight

ratio

Young *8 modulus ,

of elasticity £/

Dynamic Longitudinal

Before After

heating heating

Linear Shrinkage ^

Before After

heating heating

Abrasion

Loss

Bags/yd^of concrete Gal/yd^ of concrete ^ inches lba/ft3 lba/ft3 Ibs/in^ Ib/in^ X iqo % % gms

p-p-1 1:1:0.

7.1 0.02 72 U.5 3.00 81 74 1470 19.9 0,852

P-P-2 O' 1:1:0.

6.3 do 72 10 2.25 80 — — 16lfl — —

P-P-3 do 6.4 do 72 18,7 5.75 76 — 59 U50 19.5 — —

P-P-4 do 6.6 do 74 13.9 0.00 79 73 57 455 , 8.0 — — 0.000 0.766

P^-5 do 6.6 do 72 15.7 5.50 79 70 -- 85 ^ ~ 0.7U — 0.050 4.990 —

Z-P-1 do 6.4 do 71 17.1 5.25 77 70 — 1255 17.9 0.731 _ _

Z-P-2 do 7.1 do 78 9.6 2.25 85 — 62 1500 24.4 — 0.650

Z-P-3 do 5.7 do 65 25.5 7.50 68 — 61 665 10,9 — — „

do 6.6 do 79 12.1 5.25 80 71 57 6.8 — — 0.067 0.916

Z-P-5 do 6.6 do 71 15.8 4.75 78 68 — 95 ^ — 0.749 ~ 0.130 2.210 —

I^P-1 do 6.9 do 83 7.2 6.75 85 68 560 8.2 0.535 — 0.U6

L-P-2 do 7.1 do 86 12.5 0.25 88 — 415 —

L-P-3 do 6.0 do 74 18.7 7.50 74 — 61 — —

L-P-4 do 6,8 do 81 9.5 5.00 83 73 — — — 0.083

L-P-5 do 6.5 do 75 14.1 6.00 79 71 — — — 0.743 — 0.170 — —

P-H-l 1:1.7:1.9 5.2 do 57 11.4 6.75 101 97 1750 18.1 1.930

P-H-2 do 5.3 do 54 11.2 3.63 101 99 91 2200 24.2 2.128 1.373 0.033 0,216

P-H-3 do 5.7 do 58 5.2 2.25 109 104 94 1670 17.3 2.455 1.360 0.110 0,180 44.3

P-H-4 do 5.1 do 56 11.5 2.75 101 102 92 580 6.3 2.313 0.560 0.000 0.450 625.5

P-H-5 do 5.6 do 57 6.6 2.75 107 102 90 290 3.2 2.340 0.527 0.217 -0.166 —

P-H-l do 5.3 do 54 11.5 5.25 102 99 — 2070 20,1 2.032 — 0.100 — —

Z-H-1 do do __ _

a-if-2 do 5.1 do 54 U.3 6.63 99 97 89 2000 22.5 1.788 1.160 0.166 0.216 —

Z-H-3 do 5.3 do 54 12.4 5.75 LOO 98 90 1445 16.0 2.089 0.922 0.060 0.190 50.0

Z-H-4 do 5.2 do 55 13.2 4.50 99 99 90 595 6.5 2.054 0.594 0.100 0.430 338.4

Z-H-5 do 5.4 do 55 10.1 6.00 103 98 88 240 2.7 2.080 0.434 0.317 -0.183 —

L-H-l do 5.5 do 60 6.8 2.75 106 100 — 2145 a.5 2.011 0.200 _

L-H-2 do 5.5 do 59 6.4 3.50 106 101 94 890 9.5 1.993 0.899 0.100 0.316 —

h-a-3 do 5.5 do 58 8.4 3.25 105 101 92 705 7.6 2.020 0.596 0.130 o.no 342.5

L—H—4 do 5.2 do 58 11.5 4.50 100 99 90 540 6,0 1.928 0.473 0,210 0.230 2266.0

I/-it-5 do 5.6 do 60 5.2 5.50 107 101 89 310 3.5 2.090 0.509 0.316 -0.183 —

P-W-1

P-t*-2 P-W-3

P-«-4

P-W-5

1:0.9:1.5

do

do

do

do

7.0

6.7

6.8

6.7

6.4

0.01

do

do

do

do

69

67

67

66

69

11.4

14.6

13.4

15.0

15.6

0.00

1.75

1.50

2.50

5.50

103

99

101

99

97

98

95

94

92

89

85

a

78

1535

1295

1150

68

15.6

14.6

13.5

1.880

1.740

1.684

1.542

1.030

0.719

0.260

0.100

0.300

0.130

0,280

0.350

-0.080

-0.650

140.8

169.2

Z-W-1

Z-W-2

Z-W-3

Z-V-4

Z-W-5

do

do

do

do

do

6.7

6.6

6.6

6.6

6,4

do

do

do

do

do

66

67

62

63

70

14.8

15.3

18.0

17.3

15.7

2.75

1.50

2.20

2.50

3.00

95

98

96

96

97

91

92

90

89

89

82

a

78

1420

1135

965

415 122

15.6

12.7

11.8

5.1

1.5

1.410

1.577

1.5U

1.399

0.856

0.629

0.451

0.000

0.000

0.060

0.120

0.130

0.330

0.400

-0.420

67.2

173.8

L-4f-l do

do

do

6.8

6.4

7.0

do

do

do

68

68

70

13.0

16.4

10.0

0.13

2.50

0.00

101

96

104

96

93 86

85

1660

565

520

17.5

6.6

6.1

1.723

1.565 0.618

0.336

0.130

0.300

0,160

0.360

0.900

0.200

203.6

299.2

- 6.7

6.6

70

70

13.3

13.6

2,CX) 100 93 83 543 6.5 1.607 0«^3

W(-5 do do 1.25 99 93 82 303 3.7 1.663 — 0.200 -0.650

P-fi-1 t/

VSr-2 P—B—

P-E-4

P-E-5

T;0.4:0.5:6,8:1.9

do

do

do

do

4.6

4.7

4.2

4.8

4.9

0.02

do

do

do

do

50

51

51

5554

17.3

15.0

16.3

12.4

11.4

6.75

2.00

7.00

2.00

1.00

94

96

94

98

100

93

92

91

91

96

84

82

86

2110

2205

576

445

22.7

26.2

7.0

4.5

1.865

1.946

1.777

1.936

2.109

1.452

0.W7

0.707

0,160

0.190

0.100

0.000

0.100

0.110

0.100

0.470

100.3

29.8

448.8

Z-B-1

Z-B-2

Z-B-3

t*-5

do

do

do

do

do

4.5

4.9

4.2

4.8

4.9

do

do

do

do

do

50

53

52

54

54

18.7

12.5

18.5

12.2

11.3

5.25

1.25

7.00

1.25

0.00

92

99

91

99

101

91

93

88

92

92

86

84

84

2770

2755

960

515

30.4

32.0

11.4

6.1

1.855

1.943

1.719

2.029

1.877

1.447

0.929

0.755

0.130

0.040

0.000

0.090

0.300

0.080

0.330

0.540

51.4

34.1

583.0

I.—B—

L-E-2

L-a-3

I^.B-5

dc

do

do

do

do

5.0

4.5

4.5

4.7

4.9

do

do

do

do

do

55

53

55

5557

9.8

16.5

12.8

14.1

9.4

0.50

6.75

1.25

4.00

0.50

102

93

98

96

102

97

90

91

92

95

82

84

86

2350

445

470

515

24.3

5.4

5.6

6.0

1.794

1.615

1.723

1,828

1.839

0.692

0.551

0.619

0.080

0.170 o.uo

0.190

0.090

0.180

0.250

0.400

110.6

785.0

522.3

^ l^er l^^atee the type of cement, namely; P-Portland. Z-Portland Poazolan, IvLumnite

•me second letter Indioatea the typie of aggregate: P-Pumice, H-Haydite, B*Rooklite The numeralB indicate: 1-cured for 28 days only; 2,3,4 and 5 -cured for 28 days and boat treated at 250’C, 500°C, 750*0, 1000*0, reapeotively.

Specinene were heated at an approxlmato rate of 50*0 per hour to maximum temperature. After equilibrium wao reached they were held at thla temperature for 5 hours.

See foot notee a and b for details of heat troatnent.

-'The Dod^ of elaetlclty and the linear ehrinkage were determined on each cylinder of each mix after the 28-day curing. These deteradnations were made to c^pare comrete mtos of the

saM des^ (See column "laboratoiy Identification") but made on different daya. The reeults, whan compared with those obtained after the several heat treatments, will show any

changee in etructure of the cylinder that thoee properties may indicate.

2/Xnaccurcte due to starength of cap,

i^CtmuxA : coarse : thru 9/16 : thru 5/16 : fine.

15

3. Concre tes , Resistance to abrasion

Test slabs of tvjelve concretes designed, using each

of the three cements, with each of the four aggregates,

respectively, were tested for abrasion and the .results are

given in table 5, The amount of concrete, by v^/eight,

abraided from the specimen is considered a measure of its

wear in actual service. The loss due to abrasion of the

tested specimens ranged from 30 to 2300 grams. In general,

the concretes, designed using Lumnite cement, vi/hen tested

at the age of 28-days, had the least resistance to this

type of abrasion. The resistance to abrasion of all

concretes irrespective of the aggregates or cements used

decreased as the temperature of the heat treatments was

increased above 250 °C and ranging up to 1000“C.

Figure 2 shows the difference in abrasion resistance

of two concretes, bpecimen A contained the high-alumina

cement and the Hayaite aggregate, and had been heated at

750 °C. The loss of 2266 grams indicated a comparatively

lov/ resistance to abrasion, Specimen B contained the

Portland pozz^>lan cexuent ano. Viiaylite aggregate and had

been heated at 250®C, It lost 174 grams indicating this

concrete had a high resistance to abrasion.

Thermal Conductivity

Figure 3 shovi/s the thermal conductivity of seven

lightweight heat-resistant concretes iiieasured at a mean



o

DENSITY

(OVEN

DRY),.

LB/CU

FT

FIG. 3

16

temperat\ope of approximately 115 ‘“P, The figure not only

shows the "k'* values for the light-weight heat-resistant

concretes included in this investigation but also the "k”

values for no fines concretes reported by Valore and Green,

as well as unpublished values obtained in an active investigation "High Air-Content Light-Vrfeight Aggregate Concrete."'"'

In addition two "k" values are shown for conventional

concrete. The corresponding weight or density (oven dry)

in pounds per cubic foot are plotted against these ("k")

values. All these results are shown in order that the

location of the heat-resistant concretes may be seen with

respect to the other types of concretes. The heat-resistant

concretes range in density from 85 to 95 pounds per cubic

foot and "k" from 2.6 .to 3.8. The "k" values in the resulting plotted curve for all concretes have an overall range

from 1 to 9 and densities from 40 to 140 pounds per cubic

foot so that the heat-resistant concretes fall approximately

in the central portion.

Table 5 gives information relevant to the mixed

concretes and some of their properties. A good portion of

this data is given as a matter of interest to illustrate the

wide ran ,es that exist in such data.

The results given indicate that most of the vjater loss

occurred between the 28-day aging period and 250®C heat

treatment. The loss of water continued with successive

Building Technology Division, Structural engineering

Section, National Bureau of Standards.
:;i ".

j L n; 'C'

V

f'i

'.M'
- 17 -

heat treatraents to 1,000°C but at a considerably reduced

rate. The compressive strengths given in table 5 indicate

that only one of the 15 concretes tested met the specified

technical requirexuent of 2600 psi. The one concrete that

complied with this requirement contained portland pozzolan

cement and the Rocklite a_,gregate with a 1:1,39 cementaggregate ratio. It is quite possible that the required

strength of 2600 psi might be developed if in one or more

of the concretes the cement content were increased. Four

of the 12 concretes increased slightly in strength between

the 28-day curing period and after the 250®C heat treatment.

In all four concretes portland or portland pozzolan cement

was used. The strength of the concretes decreases rapidly

after heating at 500 °G, especially when portland or portland

pozzolan cement was used. The concretes containing Luranite

have a tendency to decrease in strength at a slower rate

after the 500°, 750° or 1,000°C heating than those containing

either of the other two cements.

Modulus of Elasticity

The maximum modulus of elasticity of the concretes,

as given in table 5, is approximately 2,000,000 pounds per

square inch. Young's modulus for concretes containing

pumice, when specimens remained intact so that this property

could be determined, was in some instances about one- third

that of the concretes made with the other four aggregates.

- 18 -

Heat treating the concretes made with pumice aggregate

caused cracking and at some temperatures com.plete disintegration, The fundamental frequency could not be

determined on cracked specimens. In all concretes the

modulus decreased rapidly with increasing heat treatments,

but ’when Lumnite cement was used this decrease was less

pronounced and tended to level off after heating at

500 ® C and above.

Linear Shrinkage

The linear shrinkage (table 5 ) after heating at the

several temperatures was quite high for the concretes

containing pumice aggregate, whereas with the concretes

containing any one of the other four aggregates it was

considerably less and in some instances a slight expansion occurred after heating at 1,000®C,

Differential Thermal Analysis

Specimens of the concretes were heat treated in a furnace the temperature of which was increased at the

rate of per hour. In order to determine the length

of time necessary to reach temperature equilibrium

throughout the 12 x 6 inch cylinders a thermocouple was

^ 19

.placed in the center of a cylinder of each concrete

and a second attached to the outside and directly

opposite the first couple. Prom the recorded

temperatures data was available for determining

differential thermal analysis curves* The conventional method of making such determinations is

described by Norton.

^

Figures 4 * 5 and 6 show

thermal curves for four specimens of three concretes

designed using the three cements, portland, portland

pozzolan, and Lumnlte, respectively, vd.th Waylite as

the aggregate* All specimens were cured for twentyeight days before heating* One of each of the four

specimens of each concrete was heated at the following

temperatures 250, 500, 750 and 1000*C, respectively*

The thermal reactions of the three concretes are quite

similar* The first inflection, between 50 and 75*0

is due to temperature lag. The Inverted peak at 100‘*C

is due mostly to the evaporation of free water* The

slight inflection occurring between 550 and 650*C

indicates the decomposition of calcium hydroxide* This
' ''S'

I'y
j!

Ij

200

400

600

800

1000

TEMPERATURE

°C

FIG.4
_ ji^

, . V.' -V

'•’

^:i'

i:.:k ''' i'M ' '"

• V ..I

f-

:\ ^ ' I

J.rt' v'#*’ ^''' -iy'

, '. .

' ;fp

‘

- 'V,

' ( <. I

,v: ' #

^ ' i

.'

.

, ^ ''', ',' i

•

U, .

• .<! «

-r ' i!' '•,.•' *< \ ^

' «

; ,Y .. - .

. Jh " ';'-l? .

. S'
o

200

400

600

800

1000

TEMPERATURE

»C

FIG 6

20

bulge is more noticeable in figures 4 and 5» the curves

for the Portland and portland pozzolan concretes. This

might be expected since the’se cements contain nearly

twice the amoimt of calcium oxide present in Lumnite

cement. All reactions occur at a slightly lower

temperature than was reported by Kalousek, Davis

10/ and Schmertz,-'-' A survey of the literature discloses

very little published data on the thermal analysis of

concretes. Por this reason it is included in this

report.

V. COIICLUSIONS

As yet insufficient results have been made available to justify any extended conclusions. It may be

definitely stated, however, that concretes containing

pumice aggregate could not be considered suitable for

warm up aprons for jet planes. These concretes not

only had low compressive strength after a twenty-ei^t

day curing period but readily disintegrated on heating

at elevated temperatures. Although considerable data

has already been accumulated the work has not progressed

to a point where a definite type of concrete can be

21

recommended for use in rigid pavements for general

ground circulation of jet-type aircraft, for warm up,

power check, or take off operations.

1/

2/

3/

Lightweight Aggregate Concrete, issued August 1949.

Standard Method of test for ’’Pyrometric Cone Equivalent (PCE) of Refractory Materials” ASTM Designation

C24-46 Manual of ASTM Standards on Refractory

Materials February 1952*

"Properties of Concrete m.ade with Typical Light

Weight Aggregates," Materials Laboratory Report

No. C-385 June 8, 1948.

k/

5/

"A Portlable Apparatus for Determining the Relative

W^ar Resistance of Concrete Floors", National Bureau

of Standards R.P. 1252, 549.

"ASTM Standards on Mineral Aggregates, Concretes , and

Nonbituminous Highway Materials", Sept, 1948.

Compressive Strength of Molded Concrete Cylinders,

page 90.

V/eight per Cubic Foot, Yield, and Air Content

(Gravimetric) of Concrete, page 121,

6/

1/

§/

9/

10/

Slump Test for Consistency of Portland Cement

Concrete, page ll5.

Proceedings of ASTM Vol. 45> 848 (1945).

Extending Application of the Fineness Modulus.

Journal of the American Concrete Institute, Part 2,

Dec. 194? Proceedings V. 43*

"Air Replaces Sand in * No-Fine s’ Concrete," Journal

of the American Concrete Institute No. 10 (1951)*

Critical Study of Differential Thermal Analysis Method

for Identification of Clay Minerals, Journal of the

American Ceramic Society Vol, 22, 1939, page 693*

An Investigation of Hydrating Cements and Related

Hydrous Solids by Differential Thermal Analysis,

Journal of the Americsri Concr'-ot.o Tn«t.i -hiite , Vol , 1949, page 693*

THE NATIONAL BUREAU OF STANDARDS

Functions and Activities

The functions of the National Bureau of Standards are set forth in the Act

of Congress, March 3, 1901, as amended by Congress in Public Law 619, 1950.

These include the development and maintenance of the national standards of

measurement and the provision of means and methods for making measurements

consistent with these standards; the determination of physical constants and

properties of materials; the development of methods and instruments for testing

materials, devices, and structures; advisory services to Government Agencies on

scientific and technical problems; invention and development of devices to serve

special needs of the Government; and the development of standard practices,

codes, and specifications. The work inchides basic and apphed research, development, engineering, instrumentation, testing, evaluation, calibration services

and various consultation and information services. A major portion of the

Bureau’s work is performed for other Government Agencies, particularly the

Department of Defense and the Atomic Energy Commission. The scope of activities is suggested by the listing of divisions and sections on the inside of the

front cover. Reports and Publications

The results of the Bureau’s work take the form of either actual equipment and

devices or pubhshed papers and reports. Reports are issued to the sponsoring

agency of a particular project or program. Pubhshed papers appear either in the

Bureau’s own series of publications or in the journals of professional and scientific

societies. The Bureau itself publishes three monthly periodicals, available from

the Government Printing Ofl&ce: The Journal of Research, which presents complete papers reporting technical investigations; the Technical News Bulletin, which

presents summary and preliminary reports on work in progress; and Basic Radio

Propagation Predictions, which provides data for determinmg the best frequencies

to use for radio communications throughout the world. There are also five series

of nonperiodical pubhcations: The Applied Mathematics Series, Circulars, Handbooks, Building Materials and Structures Reports, and Miscellaneous Publications.

Information on the Bureau’s pubhcations can be found in NBS Circular 460,

Publications of the National Bureau of Standards ($1.00). Information on cahbration services and fees can be found in NBS Circular 483, Testing by the National

Bureau of Standards (25 cents). Both are available from the Government Printing Office. Inquiries regarding the Bureau’s reports and pubhcations should be

addressed to the Office of Scientific Pubhcations, National Bureau of Standards,

Washington 25, D. C.