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NATIONAL BUREAU OF STANDARDS REPORT

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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. Tuma, L. E. Mong

and R„ A. Clevenger

<NBS>

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
U. S. DEPARTMENT OF COMMERCE

Sinclair Weeks, Secretary NATIONAL BUREAU OF STANDARDS

A. V. Astin. 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 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 back cover of

this report.

WASHINGTON, D. C.

Electricity and Electronics. Resistance and Reactance. Electron Tubes. Electrical Instru- ments. Magnetic Measurements. Process Technology. Engineering Electronics. Electronic

Instrumentation. Electrochemistry.

Opt ics and Metrology. Photometry and Colorimetry. Optical Instruments. Photographic

Technology . Length. Engineering Metrology . Heat and Power. Temperature Measurements. Thermodvnamics. Cryogenic Physics.

Engines 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 Chemistrv. Analytical Chemistry.

Inorganic Chemistrv. Electrodeposition. Gas Chemistrv. Phvsical Chemistrv. Thermochemistry. Spectrochemistry. Pure Substances.

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

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

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

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

M ineral Products. Ceramic Engineering. Porcelain and Pottery. Glass. Refractories.

Enameled Metals. Concreting Materials. Constitution and Microstructure.

Building Technology. Structural Engineering. Fire Protection. Heating and Air Conditioning. Floor, Roof, and \V all Coverings. Codes and Specifications.

Applied Mathematics. Numerical Analysis. Computation. Statistical. Engineering. Mathematical Ph \ sics. Data Processing Systems. Components and Techniques. Digital Circuitry. Digital Systems.

Analogue Systems. Applications Engineering. • Office of Basic Instrumentation • Office of Weights and Measures

BOULDER, COLORADO

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

(Lis Liquefaction.

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

Propagation Services.

Radio Propagation Engineering. Frequenex l tilization Research. Tropospheric Propagation

Research.

Radio Standards. High Frequenex Standards Branch: High Frequency Electrical Standards.

Radio Broadcast Service. High Frequency Impedance Standards. Microwave Standards Branch:

Extreme High Frequency and Noise. Microwave Frequenex and Spectroscopx . Microwave

Circuit Standards.
NATIONAL BUREAU OF STANDARDS REPORT

MBS PROJECT NBS REPORT

0903-20-4428 October 5, 1956 4869

QUARTERLY REPORTON

EVALUATION OF REFRACTORY QUALITIES OF

CONCRETES FOR JET AIRCRAFT WARM-UP, POWER CHECK,

MAINTENANCE APRONS, AND RUNWAYS

by

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

and R. A. Clevenger

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/H34-C

Approved:

Dr. Samuel Zerfoss

Chief, Refractories Section

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

The publication, r

unless permission

25, D, C. Such pe

cal ly prepared If

Approved for public release by the r In part, is prohibited Director ot the National Institute of ,andar(ls - Washington Standards and Technology (NIST) e P°rt has been

s

P

ecifi - on October 9,2015.

eport for i,s own use '

QUARTERLY REPORT

ON

EVALUATION OF REFRACTORY QUALITIES OF

CONCRETES FOR JET AIRCRAFT WARM-UP, POWER CHECK,

MAINTENANCE APRONS, AND HUNWaYS

1. INTRODUCTION

This phase of the project includes the determination of the cause o

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

An Advisory Group, formed for the guidance in furthering the study

of pavements resistant to the action of jet and rocket exhaust, at a

meeting, held at the Ohio River Division Laboratories, suggested that a

crushed rock of fine grained texture might be used to advantage as an

aggregate in such concretes. A survey of rock deposites resulted in the

selection of a diabase from Centerville, Virginia. Figure 1 is a

photomicrograph of a thin section of this diabase between crossed nicols

Interlaced bladed grains of feldspar and the dark mineral pyroxene

hornblende are apparent. The rock has a low porosity and is practically

quartz free. The latter two items offer much promise for a stable

nonabsorbent aggregate. This material has been substituted for olivine

formerly included in the list of aggregates under study. Three tons of

this diabase has been received. The material was crushed on receipt.
' K rlWI VOVX08

A *
Figure

1.

Photomicrograph

(150

X)

(Crossed

nicols)

Showing

Feldspar

Pyroxene

grains

/practically

no

quartz_/

in

a

Diabase

fror

Centerville,

Virginia.
mtm
-2-

however, a screen analysis indicated that additional sizing would be

necessary to obtain the desired fineness moduli for the coarse and fine

aggregate. The results of such preliminary tests on the aggregate as

Los Angeles abrasion test, bulk specific gravity of coarse and fine,

percent absorption of coarse and fine indicate that a concrete could

be designed that would develop the required flexural strength using the

some percentages of coarse and fine aggregate , same cement content, and

water-cement ratio as reported for concretes using Bluestone aggregate,

NBS Report No. 2832, September 30, 1953, Table II (P-3S-1, 2 or 3). A

batch of this design has been mixed and five test- panel. s, 18 x 18 x 6

inches, together with other test specimens, were fabricated and are

being cured.

A series of five test panels were subjected to the jet blast during

the period covered by this report. These panels were fabricated with

concrete designed using crushed olivine aggregate and Portland cement.

All were cured for 28 days in the fog-room and tested after storing at

73°F and 50 percent relative humidity for 14, 28, 42, 56, and 70 days.

Due to the rapid destruction of the test area the usual five-minute

interval of test was reduced to 1, 1, 2, 3, and 3 minutes respectively.

Even with this modified time of impingement the six-inch diameter test

area of each panel was spalled away. The depth of the cavity at the

center of the test area reaching two inches.

Additional work was done in an effort to determine the effect of

the water absorped by the aggregate during the soaking and curing

periods on the resistance of the concrete after partial drying. Three
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sets, each set comprising ox one sample (+ No. 1 screen) of each of. the

four aggregate olivine. White Marsh gravel, crushed building brisk,

and diabase, were dried at 110° to constant weight. One set was

immersed in a water repellent silicone resin for 24 hours, dried at

room temperature and immersed in water till tested. A second set

received the drying treatment only and was stored in desiccator till

tested, A third set was saturated and immersed in water till tested.

All specimens were exposed to the jet blast (1200°F - 1200 ft/sec,

velocity) for two minutes. The quartzite (White Marsh) specimens all

cracked badly, the cracks eniinenting from the original irregular surface

fractures. The specimens of olivine and building brick treated by

immersion in water craeked, especially the olivine which sugared, but

previously dried specimens withstood the test. Water-proofed specimens

of brick and olivine did not crack in the jet blast tests. There was

no indication of failure in any set of the diabase particles.

A study of the concentration of water in concrete during curing

and drying is being continued. The three variables, type of aggregate,

cement content, and mixing water, involved in the composition of

concrete are factors in the concentration of water in concrete during

curing and dxying. The drying of tile shape specimens, three by three

inches, having different thicknesses has been continued. The onehalf -inch thick specimens, vapor proofed on all but one three by three

inch face have reached water equilibrium in an atmosphere of 73 °F and

50 percent relative humidity. The thicker specimens continue to lose

weight even after a four month exposure.
.
-4-

Additional specimens have been fabricated using separately weighed

batches for each specimen. This was done to eliminate possible variation

in composition which may have occurred in the first seo of specimens all

cast from the same batch. Such variations were indicated by anomalous

results,

A second set of tile specimens have been fabricated. This set was

made in two seri.es similar in shape and size to the set under study but

one tile of each thickness was cast with a cavity. The dimensions of

the specimens and positions of the cavities arc given in Figure 2. All

specimens are now in the fourth week of the curing period. The weight

and volume changes of the specimens have been determined at seven“day

intervals

.

The relative humidities in the cavities, indicated in Figure 2, will

be determined during the drying cycle by means of a hygrometer illustrated

in Figure 2. These miniature ceramic hygrometer sensing elements are

3/8" x 3/8" x 1/4". They have a range of 50 to 99 percent relative

humidity and are calibrated for use with an electric hygrometer Indicator.

It is planned to correlate humidity and weight loss during the drying

period especially in the specimen of one and one and one-half thickness.

The variations in humidity with the depth below the exposed face, after

various drying intervals, will also be determined. Similar studies have

been reported by Menzel The miniature size of these hygrometers,

furnished by the American Instrument Company, will facilitate a more

critical study.

V

"A Method for Determining the Moisture Condition of Hardened Concrete

in Terms of Relative Humidity," Reprint of the Proceedings of the A.S.T.M,,

Vol. 55, 1955, Portland Cement Association Bulletin D-4.
_

'

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D

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2

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-5-

3. DISCUSSION OF STEM PRESSURE AS A FACTOR IN THE FAILURE OF

CONCRETE IN THE JET IMPINGEMENT TEST

The measurement of water vapor pressure developed in a concrete

specimen during heating is being considered. While pressures developed

by water alone can be obtained from the steam tables, the temperatures

for the same pressure may be altered greatly in concrete by the chemical

o / bonding of water with the cementing material The pressure-temperature

relation for water in concrete would be expected to be a factor in the

disintegration of concrete during heating along with other factors such

as strength, thermal stresses, thermal conductivity, heat capacity, and

permeability to fluid flow. Most of these properties have essentially

constant values, but permeability may vary over a wide range and affect

the extent of the steam pressure developed. The purpose of the experimental work would be to obtain some measure of the net pressure resulting

from the relief by fluid flow of the total pressure developed in the

pressure-temperature relation.

The significance of the forces resulting from volatilization of

water in fracturing concrete during heating is evident from the jet

impingement tests. In these tests, fractures occur at temperatures in

the range of water evolution rather than in the higher ranges ^vhere

thermal spalling stresses are developed by non-uniform thermal gradients.

An exception to this is the concrete made of White Marsh gravel whose

larger particles alone may 3pall in the lower temperature range even

when the sample is dry

.

17

"Studies of the Physipal Properties of Hardened Portland Cement Paste,"

T. C. Powers and T. L. Brownyard Research Laboratories of the Portland

Cement Association, Journal American Concrete Institute, Vol„ 43, 101,

October-April 1947.
'

.
-6-

In order to develop a sufficiently large steam pressure to cause

fracture of the concrete during heating, the supply of avaij.ab^e ; rater

and rate of evolution must overbalance the flow of steam to the surface

„

The importance of permeability and the rate of heating in setting up

this condition is evident.

The factors affecting water permeability of cement paste and rocks

3/

has been discussed by Powers et al. . The factors of interest here were:

1) Permeability decreases approximately 1 million times during

setting and curing of Portland cement. Low permeabilities were obtained

after 24 days.

2) Permeability increases rapidly for the high W/C ratios, and the

rate changes rapidly at about a W/C = .45

3) Coefficients of permeability were extremely small for cured

-12

cements and ranged from approximately 5 to 75 x 10 cm per sec.

4) Gentle drying (208 days at 93 percent relative humidity, 3.040 days

at 79 percent relative humidity, and 238 days at 100 percent relative

humidity) increased the permeability about 70 times.

5) Permeabilities of 12 kinds of rocks, often used as aggregates

(traprock, quartzitic types, limestone, sandstone, granite), were in

the range of the permeabilities of pastes having a W/C ratios from

.38 to .71.

6)

The amount of evaporable water in a paste, having the same

permeability as a given rock, was from 10 to 30 times more than in the

rock.

‘ 5/

"Permeability of Portland Cement Paste", T. C. Powers, L. E. Copeland,

J. C. Hayes and H. M. Mann. PCA Research Dept. Bulletin 53, April 1955,

Journal American Concrete Institute, Proceedings £1, 285 (1955).
^ : c .-nS nl .10 810 m

.

'

£1
-7-

These data indicated that:

1) The cured cement paste and aggregate of the concrete have about

the same low permeabilities.

2) Drying greatly increases the permeability of the paste j and this

finding is in accordance with the lack of spalling in the jet impingement

tests on dried concrete slabs.

3) The use of Portland cement as a cementing material in concrete

necessarily introduces the major part of the destructive water for the

jet impingement tests

„

4) The major improvement in performance of the concrete slab in the

jet impingement test would result from a large increase in the permeability

of the cured and treated cement paste which constitutes the continuous

phase

.

5) A minor improvement in performance would be expected from a large

increase in the permeability of the aggregate.

3 cl Plans for Next Quarter

It is possible that the steam pressure generated in concrete may

not be so high that it necessarily causes failure. It is suggested that

the pressure-temperature relation of concrete and water mixture be

determined. The determination of this relation at several rates of heating

may give some data on the thermal gradient and temperature at fracture.

The concrete would be placed in a bomb having temperature and pressure

indicators. A better procedure would be the determination of pressures

within the concrete during the jet impingement test, but miniature

pressure-sensing elements for such studies have not been developed.
,

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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 includes bas>c 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 front 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 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 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, and Miscellaneous

Publications.

Information on the Bureau’s publications can be found in NBS Circular 460, Publications of

the National Bureau of Standards ($1.25) and its Supplement ($0.75), available from the Superintendent of Documents, Government Printing Office. Inquiries regarding the Bureau’s reports and

publications should be addressed to the Office of Scientific Publications, National Bureau of

Standards, Washington 25, D. C.
NBS

r