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NATIONAL BUREAU OF STANDARDS REPORT

4767

Q'i'idbidL

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. 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 div isions 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.

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

Teehnologv. Length. Engineering Metrology.

H eat and Power. Temperature Measurements. Thermodvnainics. Cryogenic Phvsics.

Engines and Lubrication. Engine Fuels. Atomic and Radiation Physics. Spectroscopy. Radiometrv. Mass Spectrometry. Solid State Physies. Electron Physics. Atomic Physics. Nuclear Physics. Radioactivity. X-rays.

Betatron. Nucleonic Instrumentation. Radiologieal Equipment. AEC Radiation Instruments. Chemistry. Organic Coatings. Surface Chemistry. Organic Chemistrv. Analytical Chemistry.

Inorganic Chemistry. Electrodeposition. Gas Chemistrv. Phvsical Chemistry. Thermochemistry. Spectrochemistry. Pure Substanees.

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

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

Organic and F ibrous Materials. Rubber. Textiles. Paper. Leather. Testing and Specifications. Poly mer Structure. Organic Plastics. Dental Research.

Metallurgy. Thermal Metallurgy. Chemical Metallurgv. 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 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 Sy stems. Applications Engineering. • Office of Basic Instrumentation • Office of Weights and Measures

BOULDER, COLORADO

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

Gas Liquefaction.

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

Propagation Services.

Radio Propagation Engineering. Frequenev Utilization Research. Tropospheric Propagation

Research.

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

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

Extreme High Frequency and Noise. Microwave Frequency and Spectroscopy. Microwave

Circuit Standards.
)

NATIONAL BUREAU OF STANDARDS REPORT

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. Tuma, L. E. Mong

and R. A. Clevenger

Refractories Section

Mineral Products Division

Sponsored by

Department of the Navy

Bureau of Yards and Docks

Washington, D. C.

Reference: NT4-59/NY 420 008-1

MBS File No. 9. 3/ 1134 -C

NBS PROJECT

0903-20-4428 July 20, 1956

NBS REPORT

4767

Approved

:

Dr. Samuel Zerfoss

Chief, Refractories Section

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

The publication, ri

unless permission 25,D.C, Such pe

cal ly prepared If

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST)

on October 9, 2015.

r In part, is prohibited

tandards, Washington

eport has been speclfireport for its own use,
O C,
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. PREPARATION AND TESTING

A study of the rate and the amount of water that is

absorbed by concrete during curing and evaporated during

drying is being continued. As mentioned in the last

quarterly report three-inch square tile of various thick'

nesses were used. The weight change of the tile during

the test was assumed to indicate the movement of water.

The two sets of tile used in this work were fabricated

using concretes designed with Portland cement and either

White Marsh or crushed building brick as the aggregate.
X

•

.
- 2 -

The specimens were weighed at seven day intervals during

curing« After the 28-day fog-room curing, they were water

sealed on all but one three by three-inch face and dried

at 73°F at a constant humidity of 50 percent. The water

lost during the drying period was determined at seven-day

intervals also

.

Five concrete panels, together with other test specimens,

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

These specimens were fabricated with concrete, designed

with crushed olivine and Portland cement, and the properties

of the fresh concrete were in agreement with those appearing

in NBS Report 3201, March 31, 1954, Table 1. Thermocouples

were positioned on the surface of the panels, within the

test area, and imbedded at one quarter and one-half inch

depths below the surface. These panels, after fog-room

curing for 28 days, will be dried, at 73°F and 50 percent

relative humidity, for increasing time intervals and

subjected to the jet exhaust. Sets of prisms (3 x 4 x 16

inches) fabricated from the same concrete batch will be

cured and dried with each test panel. These prisms will

be used to determine such properties as shrinkage. Young's

modulus of elasticity and flexural strength. Tile, of

the same concrete, three inches square with increasing

thicknesses from one-half to six inches will be used to

determine the movement of water in the concrete during

curing and drying
X

..
-3-

Ten concrete panels (18 x 18 x 6 inches) were subjected

to the jet blast. All ten were designed using Portland

cement. Five contained White Marsh aggregate and five

crushed building' brick. All panels were cured for 28 days

in the fog-room but the drying period varied at seven, or

multiples of seven, day intervals. Each panel was placed

in position perpendicular to the jet stream and subjected

to a five minute exposure. The temperature, in the combustion

chamber, of the hot gases was kept constant at 1400°F which

resulted in temperature of approximately 1200°F on surface

of panel. The velocities were constant at 1200 feet per

second

.

An examination of the panels after exposure to the jet

blast has shown that when failure occurred the aggregate

fractured parallel to the exposed surface. This type of

failure suggested that it might be due to water absorbed

by the aggregate and expanded to steam during exposure to

jet blast. To determine the liability of the aggregates

alone to this mode of fracture pieces of three aggregates.

White Marsh gravel, crushed building brick, and crushed

olivine, were selected according to size (-1 1/2 + 1 inch)

and shape. Surface texture and coloration were added

factors in selecting the White Marsh and olivine aggregate.

One set of specimens of each aggregate was dried at 110°C

to constant weight. A second set was saturated. All
.
-4-

specimens were placed in a wire mesh container and positioned

in the jet stream at 1200°F and velocities of 1200 feet per

second for a two -minute int e rva

1

.

3. RESULTS AND DISCUSSION

The cur ve s given in Fi gure 1 indicated that there was

a variation of water with t ime and the thickness of the

specimen which had a single exposed face.

Cons ide r ing the gain i n moisture during the 28 -day fogroom curing. the relation

:

T T 3 _ rp d Vv — -L c c or W =

c Tc

a c (1)

whe re, W

c = increase i n wa ter in pe r cent of the

we ight of the (one day old) concrete

when placed.

G = Time, in days , after placing

a

c = constant for a given specimen of a given concrete during curing.

This relation fits the data quite well within the curing

period of 28 days but obviously would not fit for longer

periods of time because water addition to the concrete would

eventually stop*

The data for the drying process follows the relation:



-5-

where, W, = water in percent lost from beginning

d

of drying process to time T^.

= Time, in days, from beginning of

of drying process.

a , = constant for a given specimen of a given concrete during drying

exposed to 50 percent relative

humidity and 73°F temperature.

This relation fits the data quite well to approximately 56

days, but cannot fit for longer periods when water equilibrium

is approached.

While a and a, are constant for a given specimen, they

c d

vary linearally with the depth of the specimen; i.e. the

dimension of the specimen at right angles to the exposed

surface, and have different values for different concretes.

During curing, for the portland-crushed building brick

concrete

:

a 19.5a - 4 (3)

c and for Portland White Marsh concrete

a 13. 4d - 6.5 (4)

c During drying, for the portland-crushed building brick

concrete

;

- 6 -

a d

= 8 . 5d - 1 (5)

and for port land -White Marsh concrete

a^ = 14.3d +1 (6)

where, d = thickness in inches at right angle

to the exposed face.

If the values of a are substituted in formulas (1) and

(2) then for curing:

for portland-crushed building brick concrete

3

/' m

W

c - V 1975^

for portland-White Marsh concrete

W ' 13. 4 d - 6.5

and for drying:

for portland-crushed building brick concrete

;, d

-

8 . 5d - 1

for portland-White Marsh concrete

2 /

"d

= / 14.3d + 1

(7)

(8)

(9)

(10)

From equations (7) through (9) it is apparent that

the portland-White Marsh concrete, having the lower cement

concentration, gains more water during curing and loses less

water during drying than the portland-crushed building brick

concrete. This performance is contrary to the expected.

- 7 -

for the water, added during mixing, available for hydration

is slightly greater in the port land-Whi te Marsh batch. Also,

since the water exchanged depends on the thickness of the

specimen, it appears that volume changes of the concretes,

dependent on the cement, the aggregate, and specimen

dimensions, may affect the pore structure and the value of

the constant a. Apparently, the factor a is dependent on a number of variables that happen to be constant for a given

spec imen

.

These equations are useful in calculating the amount

of water present in concrete at any given time provided an

accurate value of a is obtained from a pair of observations.

Fortunately, a is quite large for thick masses of concrete

and the resulting change in water is small during curing

and drying. The results for the small laboratory specimens

reported in Figure 1 are interesting in explaining the

changes in water, but have limited application for large

masses of concrete.

The total quantity of water present in a concrete

specimen at a given time, desirable for correlation with

losses resulting from the jet impingement test, can be

expressed by the following equation:

(ID

where, ¥ = total water present in batch at the

m

time of placing
X
- 8 -

Since W falls in the ranae from 6.5 to 8.5 percent

m

of the batch, the amount of water exchanged during curing

and drying may be insignificant since it ranges from about

0 to 3 percent. The determination of water actually present

by taking the sum of these three quantities is not desirable

due to possible accumulated errors.

Direct measurements on cores from the concrete would be

desirable to obtain the total water and its distribution

as pore water and hydration water. Hydration water is

subject to definition but can be differentiated from that

held by other mechanisms. The distribution of water within

the concrete mass would be obtained from cored samples or

by embedded humidity indicators, of the Dunmore type, rather

than from specimens of different thickness which are subject

to variables due to the mass of the specimen

.

The temperat ure as indicated by the rmoco uple s placed

at various positi on s on the test are a and at differ ent

depths below the sur face of the test ed panels fall in the

bands shown in Fi gures 2 and 3 . The width of the b ands

show the variation in temperature that occurred during a five-minute exposure of two sets of five panels each. The

width of the bands is a measure of the accuracy of the

'Studies of the Physical Properties of Hardened Portland

Cement Paste" by T. C. Powers and L. T. Brownyard,

Bull. 22, J. Amer. Concrete Institute.

400

300

200

I 100

000

900

800

700

600

500

400

300

200

100

0

Fig. 2 Temperature Ranges, as Indicated by Thermocouples) During Jet

Impingment Tests on Five Panels Designed with Crushed Building

Brick and Portland Cement. _____ PANEL I _ — PANEL 4

PANEL 2 -

1/7771 3" LEFT OF CENTER, ON SURFACE

liTTTn 3" LEFT OF CENTER, BELOW SURFACE

123 CENTER, j

BELOW SURFACE ^

3"RIGHT OF CENTER,^ BELOW SURFACE

(23 CENTER, ON SURFACE ^ 3" RIGHT OF CENTER, ON SURFACE

DISCUSSED IN TEXT

2 3 4

DURATION OF TEST, MINUTES

5

1400

I 300

1200

I 100

1000

900

800

700

600

500

400

300

200

100

Fig. 3 Temperature Ranges, as Indicated by Thermocouples, During

Jet Inpingment Tests on Five Panels Designed with White Marsh

Aggregate and Portland Cement.

1

P7771 3" LEFT OF CENTER, ON SURFACE

rm 3" LEFT OF CENTER, j

BELOW SURFACE

VTA CENTER, £ BELOW SURFACE

3"RIGHT OF CENTER,^-" BELOW SURFACE ^

CENTER, ON SURFACE

1^1 3

11 RIGHT OF CENTER, ON SURFACE

DISCUSSED IN TEXT

I I

I

I 2 3

DURATION OF TEST, MINUTES
V
-9-

pLa.ce me at of the thermocouples and the positioning' of the

'Jt^=sir"'p3gteJ in reference to distance and angle to jet stream,

r The da_sh. Tilted, with origin in some band but deviating

- frrmm'Lt p- jjKiiciaJie' the abrupt change in temperature associated

with ' rracrra

r

e-.-

The-'terrpe'TainLxe- of" the buried the ririo couple s , when exposed

by spalling of the surface, rapidly approached the surface

temperature. Tb is -ev i dance of fracture occurred in most

instances. during the -first -one and one-half minutes of the

tes-t c

¥h.en- t.hje- -temper at ure ,, as indicated by the surface

couples, left the band, this deviation was probably caused

by a -change—in dlre-ct ion of the impinging gases caused by a

clraitge- in- contour -of the exposed area.

Table 1 -g-ivee-t he -modulus of elasticity (dynamic method)

and flaccural strength of ( 3 x 4 x 16 inch) prisms cured and

dried it. the. name manner and fcr the same time interval as

the- respective test' panel. Increasing the drying period did

not materially effect these properties. Drying at a controlled temperature of 73°F and 50 percent humidity

resulted in negligible losses of water during the drying

“time in contrast to... -larger and variable xossss previously

reported- for' panels exposed to variable atmospheric conditions..

This in turn would favor the hydration process for the

c o nluulldd at mo^pjrcrre .

Table 1.

Some

Properties

of

the

Concretes

and

Spalling

Loss

of

Panels

During

Jet

Impingement

ag

*H

0)£o

is

4-1

73O

-i-J <d t—I do

-doxo£

CD£dI—1 o>

•nd

tdw

(3)

-M

>> rQ

73

CDd£

isO

td

®

O

Q

Ph o

co

O' to d (D -H 4-!id d d

73 -h£ w

>.O

(0 £

73 +•> d to

CD td > £ 0

CO 4-> w

73

O

d -M

td 4h

O' o c

-h

d

is o d -h u -M

td £ is o d o 73

is! CD O' A o EH 4sw • ^ >>

id -t-J 73 *tH 73 i—! -fS CO £d

is

A

a> -p a> 4s >

cd *—t

-d 73 td ® r-i 4-* ®

to is

CD +J +Jd

to CD td o £ isCD rH ft ©d o

td

m

ft 73 w d

ti td jd

73

<1> d

-H£

is®4-> CD 73OS

td| 43| Ol 73] a>|

Spalling

loss

visible

but

not

measurable

by

methods

used.
/
-10

The total water content at time of test was the sum

of the water added while mixing plus that absorbed during

curing minus that evaporated during drying and was

determined on the (18 x 18 x 6 inch) panels. This water

content does not necessarily represent the amount of water

present in that portion of the panel subsequently fractured

in the jet impingement test. The spalling loss of the

tested panels ^lJas determined by two methods. The first

method, from weight, was calculated as cubic centimeters

of volume which was equivalent to the difference in weight,

obtained from the weights of the panel before and after

testing, divided by the calculated density. The second

method, from volume, was the volume of sand required to

fill the cavity remaining after impingement test. The

first method probably included the water avaporated from

the concrete adjacent to the cavity. This probably accounts

for the high value when determined by the first method.

Figure 4 shows the shape of the concrete fragments

removed by fracture. The size of the particles, however,

increases with time of test and depth of failure. An

examination of the flake like fragment indicates no bond

failure

.

The results o f the exposure of aggregates of Mhite

Marsh and crushed building brick to the jet stream for two

minutes are shown in F igure 5

.

The two dark specimens are

+J q; w c

QJ fO

•ft ft

OJ

+j 4-4 c o

mE a

Cp o C (0 -H 4h

ftE o

Cpc

-r-t

-0

0)c

iri ftE

o

4-1

<uft

ft ' O &

ft (D iH

+j >

a) -C <p

4-4 ij> T3

in a)

4->c c

id it) E

fcr 4-1

IT) 4-4

>h aj ft ft]

right

a

surface

parallel

Figure

5.

Lark

specimens

are

brick

aggregate,

light

specimens

are

White

Marsh

gravel;

left

specimens

previously

soaked,

right

specimens

dried

tc

constant

weight.

-lithe crushed building brick and the two light are the White

Marsh gravel. The two specimens on the right, one light

and one dark, were dried to constant weight before exposure.

The two on the left were saturated. Both saturated specimens

were shattered by exposure. The White Marsh fracture

followed no definite pattern. The building brick failure

shows the usual fracture that occurs in dense ceramic

materials. The specimens of olivine included in this study

whether completely dry or saturated did not fracture. The

results of this improvised test would indicate that the

presence of water in the aggregate of concrete is a factor

in its destruction when heated rapidly.

A conference was held at this Bureau, June 14. The

names of those attending follow:

F. Knoop

Bureau of Yards and Docks

P. P. Brown

John Bishop NAVCERELAB

S . Ze rf os s National Bureau of Standards

W. L. Pendergast

The purpose of the conference was to formulate a program to be undertaken by NAVCERELAB that would augment

the presently planned investigation at the National Bureau

of Standards

- 12 -

A review of the work completed at this laboratoryindicated that a further study of the following phases

would offer material assistance toward the accomplishment

of the basic objective of the project.

(1) Moisture content determined by capacitance

measurements

(2) Effects of aggregate size.

(3) Effect of rate of heating on neat cement.

All present concurred in the de s irabilit 3

r of continuing

these studies at NAVCERELAB.

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.
NBS