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NATIONAL BUREAU OF STANDARDS REPORT

Fire Research Istforsnatio;;? ^er^aes 57 3 6

National B?r.reau of Standards

By?. 225, Rm. A40

Washington, D.C. 20234 ^ QUARTERLY REPORT

ON

EVALUATION OF REFRACTORY QUALITIES OF

CONCRETES FOR JET AIRCRAFT WARM-UP, POWER CHECK,

MAINTENANCE APRONS, AND RUNWAYS

by

W. L. Pandergast, E. C, Turna , L. E. Mong

II. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
THE NATIONAL BUREAU OF STANDARDS

FtinclionH and Activities

The functions of the National Bureau of Standards are 6et 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 includes basic and applied

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 back cover.

Reports and Publications

The results of -the Bureau's work take the form of either actual equipment and devices or published papers and reports. Reports are issued to the sponsoring agency of a particular project or program. Published papers appear cither 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 Office: 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 determining the best frequencies to use for radio communications throughout

the world. There are also five series of nonperiodical publications: The Applied Mathematics

Series, Circulars, Handbooks, Building Materials and Structures Reports, ami ’ Miscellaneous

Publications.

Information on the Bureau's publications can be found in \ BS Circular i60. Publications of

the National Bureau of Standards (11.25) and its Supplement ($0.75), available from the Superintendent of Documents, Government Printing Office, Washington 25, I). C.

Inquiries regarding the Bureau's reports should be addressed to the Oflice of Technical Information, National Bureau of Standards, Washington 25, D. C.
NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT MBS REPORT

0903-20-4428 January 22, 1958 5736

QUARTERLY REPORT

ON

EVALUATION OF REFRACTORY QUALITIES OF

CONCRETES FOR JET AIRCRAFT WARM-UP, POWER CHECK,

MAINTENANCE APRONS, AND RUNWAYS

by

W. L. Pendergast, E. C. Turaa, L. E. Mong

Refractories Section

Mineral Products Division

Sponsored by

Department of the Navy

Bureau of Yards and Docks

Reference: NT4-59/NY 420 008-1

NBS File No. 9.3/1134-C

Approved

Dr. Samuel Zerfoss

Chief, Refractories Section

IMPORTANT NOTICE

NATIONAL BUREAU OF Vtf

intended for uae within the i to additional! evaluation and ? Slating ofthis Reportt either i the Office of the Director Nal however! by the Government

to reproduce additional ooplei

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST) on October 9, 2015.

progress accounting documents

finally published It It subjected

reproduction, or open*llteratura

slon Is obtained in writing from

Such permission It not needed

prepared If that agency withal

<NBS>

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
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QUARTERLY REPORT

ON

EVALUATION OF REFRACTORY QUALITIES OF

CONCRETES FOR JET AIRCRAFT WARM-UP, POWER CHECK,

MAINTENANCE APRONS, AND RUNWAYS

1. INTRODUCTION

This phase of the project includes the determination of

the cause or causes of failure that occur in concrete aprons

and runways exposed to jet exhaust gases. A combustion

chamber that delivers hot gases at velocities and temperatures approximating those of field conditions is being used.

The approach includes instrumentation of the concrete test

panels to determine the heat gradients and stresses set up

during flame impingement at several locations on the test

area and at varying depths below the surface.

2. ACTIVITIES

2.1 Pressure Developed in Concrete

During Heating

During the period covered by this report five additional

pressure-temperature curves were drawn from data taken in

five tests in which a stainless steel bomb and mercury

filling was used. All of the new data was obtained on

concretes. The results of these tests that appear in Table 1 corroborate the findings previously reported.

The effect of the presence of the aggregate was to limit

the temperature for initial pressure to values of 140 to

168°C which is only slightly higher than that for brick

aggregate alone (133°C). The removal of capillary water by

Table

1.

Data

from

Pressure-Temperature

Curves

for

Neat

Cements

and

Concretes.

-3-

roora temperature evacuation did not effect the temperature

of initial pressure possibly due to a development of open

pores. This performance is in contrast to the behavior of

the Lumnite and Alcoa neat cements for which specimens

without capillary water had an appreciably higher temperature

of initial pressure.

The characteristics of all the pressure-temperature

curves were discussed in detail in N.B.S. Report 5601.

It should be noted that all of the concretes studied

had temperatures of initial pressure within the range of 140

to 16 8°C regardless of their condition of dryness. Pavement

concretes of the same design can be expected to develop

pressures in the same temperature range.

Since in all hydraulic cements, or concretes containing

such cements, the ever present damaging -water, capillary

and/or combined, is present and some means must be developed

for the egress of such water.

2.1.2 X-ray Examination

Samples of Portland, Alcoa, and Lumnite cements were

taken from the bomb charges for X-ray examinations.—^ The

samples were taken after hydration, after evacuation at room

temperature, after the heating cycle of the bomb test, and

1 / X-ray examination made by S. Schneider, Refractories

Sect ion

.
3 Q

\ V.
-4-

after heating to constant weight at progressively higher

temperatures.. The purpose of this study was to gain more

information concerning the hydrates present in the cements

after the several treatments and to determine the maximum

temperature for complete hydration of these comparatively

stable compounds containing only a small percentage of water.

The crystalline materials identified by X-ray are given in

Table II. The amorphous compounds are not included*

The alumina present in the six samples may have been

added as excess alumina during the process of manufacture.

The hydration of the cement was not completed, during the

14-day curing period, as indicated by the presence of

anhydrous cementing materials, CA and CA 0 but these compounds

were apparently reduced to non-de ta ct able amounts during the

bomb test. The hydrates C„AH 0/ CAH, n , and AH_ were present

in the cured cement but were not detected follov/ing the

bomb test. The hydrated compounds present following the

2 / bomb test were AH and C^AgHg— which persisted even after

heating at 600°C in air atmosphere. The temperature will be

increased to determine the maximum necessary for the stability

of these compounds. The heat treatment such as that occurring

This compound is the same as reported by Johnson and

Thorvaldson, "Hydration of the Aluminates of CA:

V Hydrothermal Decomposition Products of C„A at 350 C.

Can. Jo Research 21B, 236-46 (1943).

99

Table

II.

Compounds,

Identified

by

X-ray

in

Alcoa

XCA

Cement— 5

tS3 TS.

CO

ffiCO o 1! X

XX

— 1

/?x

AH

X

X

X

co|X

CO

ffi

x X?

10

ffi

•sd50 o X

colX o

rH

ffi <o X

X

CO

ffi

•st!CO O

X

CXI I CO <O

XX

X 1

/r

¥a

X

X- -

cm|

K3j

X

X

X

X

XX

Treatment:

Bomb

#13

Before

Bomb

Test14

days

Curing

p

Bomb

#13

Plus 7

Days

Evacuat

ion

Bomb7

#12

After

Bomb

Test

Max-Temp.

280°C

Bomb

#12

After

Bomb

Test +20

0°C 1

Bomb

#12

After

Bomb

Test

+30

0°C 1

Bomb

#12

After

Bomb

Test

+600°C •CPO

P.eoo

4-)OCO

pd

+j

(t) dnx

ffi<D TJ

ffi +»

cfl o

•H

T)C

•H o

co

ffi

II

XI—I

ffifd

ffiOdwc - o O -H

nJ 4-! O O®

II r-i

<+-) o o

+J 1-1 d * ® x — £ <o ® d — O I x

CO tfl O P

co

O

O i—I In

t=rj X5 -4-> X 4-1

II ffid ffi < <! CO

r—1 1 W] CO| -^j

Unidentified

compound:

Similar

to

C.A„HStrong

Line d=

3.1628

- 6 -

in the bomb test or jet impingement test, where water is

retained, produces a different set of hydrated compounds

in the cured cement.

2.2 Water in Concrete During Curing

and Drying

The study of the correlation of the concentration of

water to the humidity within cured concrete is being

continued. Specimens described in Figure 2 of N.B.S.

Report 4869 were fabricated, humidity, and weight readings

are being taken while drying at 35 percent relative humidity

at 77°F

.

The hygrometers furnished were minature Dunmore type

and had a calibration accuracy of 1 two percent. Four sets

of hygrometers are necessary to indicate the humidity

throughout the range of 40 to 100%„

Large errors were noted when hygrometers were substituted in order to change the range, and the first set

did not indicate 100 percent when inserted in the tile, upon

removal from the fog room. These large errors seem to be

corrected by sealing the assembly joints with Glyptol cement.

These joints were exposed to the flow of the drying air.

Another source of error was the unreliable seal between

the concrete tile and the plastic, moisture proof, jacket.

This seal has been improved, in preparing a new set of tile

now under study, by cementing the plastic sheet to the tile

-7-

with, Pliobond. The sealing is important when determining

the moisture gradient within the tile at different depths.

The relative humidity at a given position in the

concrete test tile and the time of drying was plotted in

Figure 1. For the higher humidities their relations were

linear but the error in the measurements made this relation

uncertain at the lower humidities. The main source of error was

the substitution of hygrometers. The first reading of the

replacement hygrometer is indicated on the graph. Figure 1,

by single or double circles around the symbol (data point)

for the second and third humidity ranges, respectively.

Although some of the data for these replacements were

within the tolerance, the offset greatly effected the slope

of the line. It is believed that this error was due not

only to an exchange of air in the tile cavity but also to

leakage in the assembly joint.

A comparison of the humidities after 63 days of drying

indicated (1) relative humidities from 61.8 to 66.5 at the

one-half inch depth in the one, two, and six inch tiles;

and (2) a range of 76.7 to 82.0 at three-quarter inch depth

in the one and one-half and four inch tile.

The increase in humidity with depth was also indicated

from the data for the two and four inch tile but the data

for the six inch tile, not included in Figure 1, was

contradictory

001

GOCD

x X X X

1— 1- 1— 1-

CL x X X

UJ Id Ld Ld Q o Q Q

PO|^J- ro|<t mi^r oo

rOl'J- st

Ld Ld" Ld' Ld" _J _l _l

1- j- j-

'X '<£>

<1 o < X

hC

X

h-X

X

1—

Q_

X

h-X

Ld Ld Ld Ld O Q O Q

—|CJ ro|st -ICO -|co

Ld Ld Ld" Ld

_) _J _J _l

P 1- J- P

-|«M 00 00

0 O X

o

CO

lN30d3d A_L I Q 1 1AI D H 3AI±V33d

~ CD

st “ 00

h- ~ r-

_ o

rrO

CO

com

_J CD

st

C\J

sjin

ro

oo

co

cot

hDRYING

TIME

,

DAYS

- 8 -

In general low humidities were found near the surface

of the tile and increased with depth. However, the humidity

near the wet face (opposite the exposed face) of the six

inch tile was unexpectedly less than that of a similar

location in the four inch tile. Such discrepancies were

assumed to result from the uncontrollable variation in

fabrication of the tile.

As pointed out in N.B.S. Report 4767 the water exchanged

in a specimen depends on the composition of the concrete,

the depth of the specimen, and the drying treatment. The

rate of drying of an individual tile can be expressed as a constant; calculated from weight loss curve according to

equation (2) of this report (N.B.S. 4767). Drying constants

(a,) were calculated for tile (Figure 1) in the present

a study and plotted with the rate of humidity change (for

the period of 35 to 42 days) in Figure 2.

For this graph the rate of humidity changes were those

at mid-depth of the one and one and one-half inch tile and

interpolated values at mid-depths for the two and four inch

tile. The graph indicates considerable correlation in the

rates of humidity change with water loss. This correlation

will probably become somewhat different as the tile dries.

CONSTANT

la)

FOR

DRYING

CURVE

RATE OF CHANGE IN RELATIVE HUMIDITY DURING DRYING

(35 - 4 2 DAYS ) FIGURE 2. RELATION OF CHANGES IN RELATIVE HUMIDITY

TO WATER LOSS.

-9-

2.3 Resistance of Neat Cement Cubes

to Jet Impingement Test

A set of 12, one inch cubes, were fabricated using

neat Alcoa, Lumnite, and Portland cement. Twenty-seven

and one-half percent mixing water was used. After a

28 day fog-room curing the cubes were subjected to drying

treatments and jet impingement tests as shown in Figure 3.

As previously reported all cement cubes fractured in the

first test. The second set of cubes, after additional

drying showed no improvement in the jet impingement test

although there was a small reduction in water content. The

third set indicated some improvement in their resistance

to the test with a correspondingly large reduction in water

content caused by the drying at 3 5% relative humidity at

77°F. The drying treatment at 230°F removed all the

capillary water in seven days and the last set of specimens

tested after 14 days at 230°F showed the best resistance

to this test. The damage to this set was restricted to the

structurally weak corners and edges.

2.4 Jet Impingement Tests on Topping Materials

Eighteen by eighteen by four inch panels were fabricated

from conventional Portland cement - sand and gravel concrete.

These panels were finished with a two inch topping (total

thickness six inches). Both topping mixes were designed

with Lumnite cement, one contained diabase aggregate the

other emery aggregate

28

26

24

22

20

18

16

14

I 2

10

8

14 0 14 28 42 14 28

| DRYING AT 50 PERCENT I DRYING AT 35 PERCENT

^RELATIVE HUM IDITY,73°PRELATIVE HUMI DITY,77°F

FOG-ROOM CURING

7 DAYS

DRYING AT_

230° F

- 10 -

The design of the toppings was as follows:

D iaba se Topping

Erne ry

Topping

3 Cement content, sack/yd 7.5 14.7

Ratio of cement to coarse

to fine, by weight 1:2. 12:1. 54- / 1:: 2-

Water cement ratio 0 .41 0.32

Gallons per cubic yard 44.9 52.3

Workab i 1 ity very good slight excess water

— ^ Maximum size on 3/4" screen. — ^ All through 3/8" screen.

Both panels were cured 14 days in fog-room and dried 14 days at

507o relative humidity and 73°F.

These panels were subjected to the jet impingement test.

The panel made r^ith Emery topping. Figure 4(L-E) shows a large

loss and the imbedded thermocouples are visible. No damage

was apparent for the Diabase topping.
i


U. S. DEPARTMENT OF COMMERCE

Sinclair Weeks, Secretary

NATIONAL BUREAU OF STANDARDS

A. V. Aslin, 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 field 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 spe- cialized 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 front cover of this report.

WASHINGTON, D. C.

Electricity and Electronics. Resistance and Reactance. Electron Tubes. Electrical Instruments. Magnetic Measurements. Dielectrics. Engineering Electronics. Electronic Instrumentation.

Electrochemistry.

Optics and Metrology. Photometry and Colorimetry. Optical Instruments. Photographic

Technology. Length. Engineering Metrology.

Heat and Power. Temperature Physics. Thermodynamics. Cryogenic Physics. Rheology

and Lubrication. Engine Fuels.

Atomic and Radiation Physics. Spectroscopy. Radiometry. Mass Spectrometry. Solid State Physics. Electron Physics. Atomic Physics. Nuclear Physics. Radioactivity. X-rays. Betatron. Nucleonic Instrumentation. Radiological Equipment. AEC Radiation Instruments. Chemistry. Organic Coatings. Surface Chemistry. Organic Chemistry. Analytical Chemistry.

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

Mechanics. Sound. Mechanical Instruments. Fluid Mechanics. Engineering Mechanics.

Mass and Scale. Capacity, Density, and Fluid Meters. Combustion Controls.

Organic and Fibrous Materials. Rubber. Textiles. Paper. Leather. Testing and Specifications. Polymer Structure. Organic Plastics. Dental Research.

Metallurgy. Thermal Metallurgy. Chemical Metallurgy. Mechanical Metallurgy. Corrosion.

Metal Physics.

Mineral Products. Engineering Ceramics. Glass. Refractories. Enameled Metals. Concreting

Materials. Constitution and Microstructure.

Building Technology. Structural Engineering. Fire Protection. Heating and Air Condi-*

tioning. Floor, Roof, and Wall Coverings. Codes and Specifications.

Applied Mathematics. Numerical Analysis. Computation. Statistical Engineering. Mathematical Physics.

Data Processing Systems. SEAC Engineering Group. Components and Techniques. Digital

Circuitry. Digital Systems. Analogue Systems. Application Engineering.

® Office of Basic Instrumentation • Office of Weights and Measures

BOULDER, COLORADO

Cryogenic Engineering. Cryogenic Equipment. Cryogenic Processes. Properties of Materials.

Gas Liquefaction.

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

Propagation Services. Sun-Earth Relationships.

Radio Propagation Engineering. Data Reduction Instrumentation. Modulation Systems.

Navigation Systems. Radio Noise. Tropospheric Measurements. Tropospheric Analysis. Radio

Systems Application Engineering.

Radio Standards. Radio Frequencies. Microwave Frequencies. High Frequency Electrical

Standards. Radio Broadcast Service. High Frequency Impedance Standards. Calibration

Center. Microwave Physics. Microwave Circuit Standards.
))))