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National Bureau of Standards

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Washington, D.C. 2Q234

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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^ and R. A. Clevenger

<NBS>

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

cr-
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 is suggested in the following listing

of the divisions and sections engaged in technical 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.

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

Instrumentation. Electrochemistry.

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

Technology. Length. Engineering Metrology.

Heat and Power. Temperature Measurements. Thermodynamics. 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 Chemistry. Analytical Chemistry.

Inorganic Chemistry. Electrodeposition. Ga s 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.

Mineral Products. 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 Wall Coverings. Codes and Specifications.

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

Data Processing Systems. Components and Techniques. Digital Circuitry. Digital Systems.

Analogue Systems.

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

Gas Liquefaction.

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

Propagation Services.

Radio Propagation Engineering. Frequency Utilization Research. Tropospheric Propagation

Research.

Radio Standards. High Frequency Standards. Microwave Standards. • Office of Basic Instrumentation • Office of Weights and Measures
NATIONAL BUREAU OF STANDARDS REPORT

PROJECT MBS REPORT

0903-20-44 28 April 12, 1955 4626

QUARTERLY REPORT

ON

EVALUATION OF REFRACTORY QUALITIES OF

CONCRETES FOR JET AIRCRAFT WARM-UP, POWER CHECK,

MAINTENANCE APRONS, AND RUNWAYS

by

W= Lo Pendergast , E. C. Turaa, and R. A. Clevenger

Refractories Section

Mineral Products Division

Sponsored by

Department of the Navy

Bureau of Yards and Docks

Washington, D. C.

Reference t NT4-49/NY 4200 008-1

NBS File No. 9.3/1134-C

Approve d

Dr. Samuel Zerfoss

Chief, Refractories Section

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

The publical

unless permi 25,D,C. S

cal ly prepai

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST)

on October 9, 2015.

hole or In part, is prohibited

iu of Standards, Washington

ich a report has been specificular report for its own use.

QUARTERLY REPORT

ON

EVALUATION OF REFRACTORY QUALITIES OF

CONCRETES FOR JET AIRCRAFT WARM-UP , POWER CHECK,

MAINTENANCE APRONS , AND RUNWAYS

PART I

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 impingment at several

locations on the test area and at varying depths below the surface.

2. MATERIALS

Approximately two tons each of olivine and crushed building

brick (dense, face) was received during the reporting period.

These materials were furnished crushed and sized.

The screen sizings were those required by No. 45Ya September

1952, Specification for Portland Cement Concrete Pavement for

Airports, Department of the Navy, Bureau of Yards and Docks. The

olivine and crushed building brick will be used as aggregate in

the concretes from which panels and other test specimens will

be fabricated.

Ten concrete panels, together with other test specimens, have

been fabricated and are being cured in the fog-room. Five were

designed with the White Marsh aggregate and five with crushed

- 2 -

building brick. All contained Portland cement. Five panels

previously reported as having been fabricated, one designed with

White Marsh and four with building brick aggregate, were subjected

to the jet blast. One panel with a one-inch topping of concrete

designed with high-alumina hydraulic cement and crushed emery

was also subjected to the jet blast. This panel was fabricated

by a contracting company engaged in installing airport pavements.

3 . PREPARATION AND TESTING

Some necessary changes were made in the combustion chamber

during the period covered by this report. The weight-lever

balance that regulated the valve furnishing the primary and

secondary air was replaced by a spring attachment that stabilized

the action of this valve. A gas compressor, of different design

and a higher capacity, was installed in the fuel (natural gas)

line. This compressor delivers sufficient gas at five psi to

permit increasing temperatures of the jet exhaust well above

the planned temperature of 1200°F. The location of the maximum

temperature in the mixing chamber was determined and the thermocouple measuring this temperature was permanently positioned.

Details of the combustion chamber are shown in Figures 1 and 1A.

A draining of the equipment was included in N.B.S. Report 4531 , Figure 4. While subjecting five panels to the jet blast,

temperatures were measured at different locations on the surface

and at depths of one-quarter, one-half and three-quarter inches.

PQ p

oo

* o -H o 0) < rd — w

, C

Pressure

gages

for

fuel,

secondary,

and

primary

air;

A',

B'

,

C'

Flow

meters

fuel,

secondary,

and

primary

air;

D

fuel

injector;

E

Mixing

chamber,

primary

and

fuel;

F

Secondary

air;

G

Ignition

and

flame

retainer;

H

Secondary

air

er

tube);

combustion

chamber

(inner

tube);

I

Mixing

chamber,

hot

gas

and

ndary

air;

J

Thermocouple,

inserted

to

center

line

of

I.
?»•<«-


-3-

The velocities of the impinging gases, at several distances

from the center of the test area, were also determined. The

impact tubes, used in determining the velocity, were placed at

different angles to the surface of the panel as well as at

different locations within the test area.

The study of the movement of water in concrete specimens,

during drying, was continued. Three-inch square tile having a thickness of either one-half, one, one and one-half, or two-inch

were fabricated from the same concrete mixes used in making the

test panels. The "total water" used in mixing the concrete

designed with White Marsh aggregate was six percent. Seven and

nine-tenths percent was used in mixing the concrete containing

the crushed building brick aggregate. The tile were fog-room

cured for 28 days and dried at laboratory temperatures and

humidities. Some received additional drying at 38° and 75°C.

They were water sealed on all but one face (three by three-inch

face) during the drying treatments. All specimens were weighed

at seven-day intervals and the water loss was calculated by the

weight loss based on weight out of molds, 20 hours after placing.

4'. RESULTS AND DISCUSSION

Figure 2 slows the effect of thickness on the absorption and

evaporation of water in concrete tile designed with White Marsh

aggregate and Portland cement. The absorption during curing and

the rate of evaporation during drying was inversely related to

the thickness of the tile. The rate of absorption and evaporation

of water was greatest for the one-half inch tile and least for

PERCENT

CHANGE

IN

WEIGHT

(

Based

on

Weight

after I

Day

in

Mold )

TIME - DAYS

-4-

the thickest two-inch tile. The rates for the one and one-half

and two-inch tile were quite similar. The drying treatment at

room temperatures and humidities caused a rapid rate of drying

for the first seven days with a decreasing rate for the remaining

21 days. The increase of the temperature of drying to 38°C again

caused a rapid rate of drying for the first seven days and a reduced rate for the remaining 14 days. .additional water was

evaporated at a rapid rate during the first seven days at a temperature of 75°C. At this temperature the rate of drying

approached zero for the remaining 21 days. The temperatures 38°

and 75°C were chosen and found to be adequate to hurry the removal

of the evaporable water. The curves show that any additional

water loss would be replaced from the atmosphere at ordinary

temperatures. Temperatures in a higher range will effect the

strength of the concrete. Out of the original six percent "mixing

water" (plus the water absorbed during fog-room curing) 2.4 to 2.8

percent was lost during the drying period. The one-half and oneinch tile appear to have reached water equilibrium after seven

days drying at 75°C. The one and one-half and two-inch tile

reached this state after 21 days drying at the same temperature.

Figure 3 shows the effects of thickness on absorption and

evaporation of water in concrete tile designed with crushed

building brick and Portland, cement. As was found in the tile

fabricated with the White Marsh aggregate the rate of absorption

and of evaporation is inversely related to the thickness. The

total absorption during curing was less than the sand and gravel

PERCENT

CHANGE

IN

WEIGHT

(

Based

on

Weight

after

I

Day

in

Mold

1.6

1.4

2 8

1 I l l I I I I I I I I I I I 0 7 14 21 0 7 14 21 28 35 42 49 56 63 70 77

[-Fog-room curing — D r y i ng at Laboratory Temperatures and Humidities-]

TIME - DAYS

-5-

concrete. The rate of drying and the amount of evaporable water

removed during drying for 28 days in the laboratory are greater

than the White Marsh concrete. After this 28-day drying period

the curves describing the water loss are approximately parallel

indicating a continual movement of water to the exposed surface.

The results of instrumentation of the test panels thus far

indicates that the temperature of the gases, as measured in the

final mixing chamber, must be maintained at approximately 1400°F

to obtain 1200°F at the center of the test panel. Placing the

test panel at a distance of three inches from the jet exhaust

permits more flexibility in temperature and velocity control.

The curves, for time intervals of two minutes, obtained by

plotting temperature and distance from the center of the test

area are shown in Figure 4. The average temperature of the gases

in the combustion chamber during this test was 139G°F. The curves

denoting the temperature at a given time at increasing distances

from the center of the test area shoX’/ steeper temperature gradients

on the surface than at one-quarter of an inch below the surface.

During the first minute, the buried thermocouple at the center

of the test area reached a temperature of oni^r 350°F. While the

thermocouple similarly placed, but on the surface, indicated a temperature of 950°F. The center surface temperature during the

remainder of the test increased to 1080°F while the temperature

at one-quarter inch depth increased to 830°F.

A graph of the temperature gradients for a panel having

thermocouples in the plane of the surface and at one-half inch

depths below this surface was similar to that of Figure 4. It was

QJ Q) > 0^ ^ g

2 <U O +J

<u

Vh3

Cn •HCM

DISTANCE

IN

INCHES

FROM

CENTER

OF

TEST

AREA

- 6 -

expected that the rate of increase in temperature and the top

temperature reached, during the fifteen-minute interval of the

test, at one-half inch depth would be somewhat less than those

at one-quarter inch depth, the difference, however, was not

apprec iable

•

The limited accuracy of the placement of the thermocouples

at precise positions and depths and the presence of such steep

temperature gradients introduce corresponding errors in temperature measurement.

The velocities of the impinging gsses, at several points on

the surface of the test panel, were calculated from the impact

pressure in open-end tubes. The formula used was

V

.

!

( 2g ) ( Pj - P Q )

V /w

Whe re V = velocity, feet per second

2 g = gravitation constant, feet per second

2 Pi = impact pressure, pounds mass per foot

2 P Q = static pressure, pounds mass per foot

(in these tests taken as atmospheric)

3 - density, pounds mass per foot

The impact tubes were placed at different angles to the surface

as well as at different distances from the center, but the calculated velocities seemed to depend largely on the location of the

tube rather than the angle of placement. This insensitiveness
I
-7-

of pitot tubes to directional velocities is discussed in

handbooks. Patterns when the velocity and distance from center

of test area were plotted were quite similar for each test. The

velocity, at the center, ranged from 1100 to 1200 feet per second;

at one inch from center, from 900 to 950 feet per second; at two

inches from center, from 650 to 750 feet per second and at three

inches from center, from 200 to 350 feet per second. The

velocities decreased at the rate of approximately 300 feet per

second for each inch from the center of the test area.

The jet blast tests completed thus far have not produced

appreciable distruction to the test panels. What few cracks

that occur emanate from the thermocouples or pressure tubes that

were cast in the panel. However, all panels were cured for 28 days

in the fog-room and were not subjected to the test until dried

for at least two months under laboratory conditions.

Chemical Engineers' Handbook, McGraw-Hill Eook Company, Inc

1950, Pages 397 and 398

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 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 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.