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NATIONAL BUREAU OF STANDARDS REPORT

4502

,-3» ffilsjaB ga.v-^-sa f. -1i

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43®-

I.J'^

^

^ T'-®sa ta

QUARTST^LY REPORT

ON

EVALUATION OF REFRACTOxPY 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

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

Mechanics. Soimd. 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

NBS PROJECT NBS REPORT

0903-a0-4428 January 25, 1956 4502

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

Refractories Section

Mineral Products Division

Sponsored by

Department of the Navy

Bureau of Yards and Docks

Washington, D. C.

Reference: NT4-49/NY 4200 008-1

NBS File No. 9.3/1134-C

Approved

Dr. Samuel Zerfoss

Chief, Refractories Section

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

The publicatio

unless permiss 25.D.C. Sue

cally prepare:

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST)

on October 9, 201 5.

le or in part, is prohibited

of Standards, Washington

I a report has been specifiar 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

The objective of the first phase of this project is

the determination of the physical properties of concretes

that will evaluate their suitability for use in jet aircraft

warm-up, power check, maintenance aprons, and runways.

2o MATERIALS: PREPARATION AND TESTING

2 .

Cements

The tests planned on the three cements in the first

phase of this project have been completed. These tests

included the chemical analysis, the determination of the

mechanical properties, such as the permanent length changes,

the water loss, and decrease in strength after heating at

increasing temperatures. The results of these tests appear

in N.B.S. Reports previously submitted.

2.2 Aggregates

All the mechanical tests on the aggregate, Kenlite,

used in the concretes tested during the period covered by

this report have been completed and reported.

2.3 Concretes

Two of the three concretes designed with Kenlite

aggregate and containing either Portland or Portland

pozzolanic cement were reported as having been mixed and

- 2 -

specimens fabricated in the last N.B.S, Report 4361

(September 30, 1955). The third concrete designed with

the same aggregate but containing high-alumina hydraulic

cement was mixed and a complete set of test specimens

fabricated during this reporting period.

3. RESULTS AND DISCUSSION

3 . 1 Concretes

Table 1 gives the properties of the fresh concretes

designed with Kenlite aggregate and either Portland,

Portland pozzolanic or high-alumina hydraulic cement.

The concretes were designed as nine sack mixes but when

the cement content was calculated resulted in slightly

richer mixes with the Portland and Portland pozzolan cements

and nearly ten sacks per cubic yard for the high-alumina

hydraulic cement. The flexural strength as determined

on numerous trial mixes of concretes of this type indicated

that a minimum of nine sacks per cubic yard would be

necessary to develop the required strength of 600 ps i

Table 2 gives the properties of the cured and heat

treated concretes. The low flexural strength given in

lines three of this table corroborates previously reported

results indicating that concretes designed with expanded

shale, crushed, aggregate requires longer curing periods

than when dense aggregate is used. The type of failure,

aggregate fracture, indicates that maximum strength has
r» A ?• I

r ^

/
Table

1.

Pronurties

of

Fresh

Concrete

,-

with

Lir^htv/uigiit

,

Kcnlitc

Fracture

all

aggregate

fractured,

fev/

air

voids.

all

aggregate

fractui'cd

numerous

air

voids

Some

as

large

as

l/8"

diameter.

feu

pull-outs,

mostly

fractured

agsrogate:

Inrge

air

voids.

iH .P if

3 u p PCO

C o

•ol

4f\ cn

vO

•oj

u-\ lA

lA

1

!

Hemarks

j

Fresh

Concrete

]1

•D

<l> O

e o o

T3 'C P

W

o

stickj'

but

easily

placed

do do

1

oxcellont

started

to

set

before

complete

placing 1

do

1

Water

1

Cement ;

Ratio

o- r- >xs CO d c o ^

“1 d d d

CV CV P fA CA C-^ d d d

1

V/eif^ht

of

Fresh

'

Concrete

tX) -J- c P (\ t3D to

C_I • . • '^ -4- rn -i-

(0 o c c Pi— P P

p POX O P o

-o o o o p p p

»A O O'

-4 CV lA

CA X X

O C O

P P P

c1

CO

S C C O

, p u~\ ir\ i/\ o • • C CV C\’ P

C UT\ C QO d (V d

»ACOOlA lA

-4- d r-i

1

—

1

C'

1

Air C

ntent

Gravimetric o -q- r.- P C- P

cv cv <v

C'- 0- o

P P C'- C\ o -4-0 0- 3 P c

nO <N

Water

Content

op0)o

c

O

u^ P -4- CV o • • • co to oc*^ c*^

wp

i?-

O -4- vO O ir\ lA ^ -J’ -4 \lA O lA

CA CA CA

^ s

o c ^ o> W P -H £

q CO o (0 •H o S o > ci “ °

LP, O o o q

-t; -o d

'«L

flboo*0 TJ c

lAO O O C XJ -o d

Cement

Content

sacks

yd^

of

concrete j

9.24 9.21 9.37

u

9.06

I

9.21

j

9.39

I

r- o P

lA O X

O' d jd

ProDortion

by

Weight

1

Cement

to

Coarse

,

1

and

to

Fine

1

Aggregate

c^

r-d

*’ 0 o O X3 *0 O'cp 1

:

0.76

:

0,95

do

1

do

-4- !>O

” o O P XJ TD O'd

p

.9P

•1 C

•H

•aP

oS

P-IC-1

'1

P-K-2

]

P-K-3

j

i

P CV CA

( 1 1 ;a p iiS

1 1 1 C4 ^3

P <\ CA

J. vL

1 T *7 v4 hJ

t£t O +5 O S C M 4) to -H

.g u I i

m H :c i

>> P 'U o

u qH

tlO c. rH

"H ^ , t U’

^ u u ^ 'a

-P ' o x> c o _ +» C c3 o TJ e c o 'H I xj

O O -P c.

6 i

e

-g

" I -H ft H H j: c

rj P> P

q ^ o ^ P O = P r

e 8. T3

p P j= ;h O O P o

p. ilJ to

to <0

y p > C rj

ct. e-4. P P o I

-

cy) ^1*01 roi 6] <1

Table 2

Prooerties

of

Cured

and

Heat-Treated

Concretes^'

A

description

of

the

apparatus

and

method

used

in

determining d

epth

of

v/ear

was

given

in

N.B.S.

Report

3201.

Based

on

length

after

2A

hours

in

mold.

Based

on

iveight

after

24

hours

in

mold.

Sncoljnens

v/arped

too

badly

for

test.

-3 -

been developed for concretes designed with this aggregate.

The decrease in strength after the 500°C heating indicates

the loss of strength in the bond (cement paste). The

condition and strength of the concrete after 1000°C

indicates that this temperature approaches that of the

original calcining.

This concludes that phase of the project concerned

with the collection of data on the thermal and mechanical

properties of concretes designed with one of the three

types of cement and one of a variety of concretes.
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PART II

1,

INTRODUCTION

The second part of the project includes a determination

of the cause or causes of failure that occur in concrete

aprons and runways exposed to jet exhaust gages. The

approach includes a measure of the heat gradients and

stresses set up by flame impingment. A combustion chamber

that will deliver hot gases at velocities and temperatures

approximating those in field conditions will be used.

2.

MATERIALS

The two concretes used in fabricating test specimens

during this reporting period were previously recommended

compositions. Portland cem.ent vras used in both mixes.

White Marsh sand and gravel or crushed building brick was

the aggregate.

3.

PREPARATION AND TESTING

Four test panels 18 x 8 x 6 inches were fabricated.

One panel contained concrete designed with White Marsh

gravel (largely quartz and quartzite). The other three panels

were fabricated with concrete designed with crushed building

brick. Three-inch tile, disks with a one and one-quarter

diameter, and brick shape specimens were molded from each

concrete. The tile and disks varied in depth from onehalf to 2 inches. The bricks were cast edgewise and flatwise

and were cured and dried in the same position. All specimens
->f »ymii
-5-

were sealed with a vapor pi'oof plastic leaving one

exposed face. During fabrication of the panels thermocouples were placed at varying distances from the center

of the exposed face and at varying depths from this face.

Pitot tubes were cast in the panels at varying distances

from the center of the exposed face and at decreasing

angles to this face.

Electrical connector plugs having exposed terminals

were cast in the panels at one-half, one, and one and

one-half inches below the exposed surface of the test

panel. These were installed for the purpose of measuring

the change in resistance of the concrete during the curing

and drying periods.

Each test specimen was weighed after one day and 28

days fog-room curing, and after 7, 14, 21, and 28 days

laboratory drying.- Some specimens have had an additional

drying of 21 days at 3 8°G and 7 days at 75°C.

The resistance of the concrete panels at increasing

depths was measured after the same curing and drying

periods.

4. RESULTS AND DISCUSSION

The electrical resistance method, used in determining

the change in water concentration, at varying depths from

the exposed surface of the concrete test panels, shows

some inconsistencies in the results. The inconsistencies
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- 6 -

may be rationalized by the fact that the conductivity of

pure water is very low and a rediiction in the concentration

of this water, such as occurs in the drying of concrete,

should result in conductivities of even smaller magnitude.

The presence of ions in this water even in extremely

minute concentration causes enormous increases in the

conductivity of the resulting solution. The conductivity

of such a solution was the property actually measured by

the method tised and therefore depended far more on the

concentration of the electrolytes present in the water

than the amount of water in the cement. The source of

"I* '4* "f* such ions mentioned could be the Ca or Na and K

from the lime and alkalies in the cement paste. In the

concretes designed with crushed building brick an additional

source was the alkalies than can be leeched from the

aggregate

The resistance of the concrete designed with the White

Marsh aggregate at the depth of one-half inch from exposed

surface varied from 15,000 ohms after 24 hours in mold to

2,000,000 ohms after an extended curing and drying period.

The resistances did not, however, decrease at the one or

the one and one-half inch depths in proportion to the

amount of water determined by other methods.

Measurements of the movement and the amount of water

present in concretes, as indicated by weight changes,

indicates that all concrete specimens tested (sealed on
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-7-

five sides) picked up water during the fog-room curing.

This increase in water content was inversely proportional

to the thickness of the specimen. The rate of loss in water

was also controlled by depth but was in direct relation.

During a 28-day drying period under laboratory conditions of

temperature and humidity, all specimens of two-inch depth or

less had lost the water absorbed during curing. After

prolonged heating at 75°C even the thinnest tile still

retained approximately four percent of the original mixing

water.

Combustio n Ch a mbejc_

The combustion chamber designed to deliver hot gases at

600°F to 1200°F at velocities of 1200 feet per second has been

completed. The pressure regulators, indicating gauges, and

flow meters necessary for the control of the air and gas have

been installed and tested.

Some exploratory tests have been made with this combustion

chamber and its exhaust gases to determine its limitations.

Specimens of concrete (18 x 18 x 2 1/2 inches) designed with

Kenlite aggregate and heated at 250°C were used as test panels.

The center line of the panel coincides with the burner axis

and is at right angles to the direction of jet. Thermocouples

and pitot tubes were positioned radially over the six-inch

diameter test area. The temperatures were measured and

recorded by a multipoint recorder - potentiometer that records

from 40 to 60 times per minute depending on the temperature
vij r? fc s ^ II T''

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- 8 -

differences. The velocity at impingment was measured in

pressure and calculated to rate of flow.

The results of the exploratory tests indicate that the

combustion chamber as assembled will deliver gases at 1200°F

to the surface of a panel at distances from one and one-half

inches from the jet opening to six inches. The velocities

at which the hot gas is delivered diminishes from ICOO feet

per second at the one and one-half inch distance to 800 feet

per second at six inches. The temperature at the center of

the six-inch diameter test surface, 1200°F, decreased to

700*^F on the perimeter of this area and the velocity decreased

from 1050 to 350 feet per second when the panel was tested at

the one and one-half inch distance from exhaust. When

temperatures and velocities were measured at a six-inch distance

from, exhaust jet there was a SOO'^F drop in temperature from

the center to the perimeter of six-inch test area and an

accompanying drop in impinging velocities of 600 feet per

second. These results indicate that it will be necessary to

increase the rate of the flow of gas in order to obtain the

desired velocities. A different type gas compressor is being

installed. Several more tests will be made before standardizing distance, velocity, and temperature of test.
,

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; "S' ^0 ' . - - 'S ^ s' i
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. Repoi^ts 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.