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NATIONAL BUREAU OF STANDARDS REPORT

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Washington, D.C. 20234

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..QUARTERLY 12EPORT

ON

EVALUATION OF REFRACTORY QUALITIES OF

CONCRETES FOR JET AIRCRAFT WARM-UP, POWER CHECK,

MAINTENANCE APRONS, AND RUN^JAYS

•-fsa by

Vr, L. Pendorgaat, E« C* Tuitia, L. E. Mong

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
THE NATIONAL BLKEAL 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 s|iecial 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. \ ni.qor portion of the Bureau’s work is performed

for other Government Agencies, particular!) 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 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 F^rinting 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 nse f<*r radio communications throughout

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

Scries, Circulars, Handbooks, BuiWling Materials and Structures Reports, and Miscellaneous

Publications.

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

the National Bureau of Standards (.If 1.25) and its Supplement ($0.75), available from the Superintendent of Documents, Government FVinling Office. Washington 25, D. C.

Inquiries regarding the Bureau’s reports shouM he addressed to the Office of Technical Information, iNulional Bureau of Stamlards, Washington 2.5, D. (,.
NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS REPORT

0903-20-4428 April 16, 1958 5855

QUARTERLY REPORT

ON

EVALUATION OF REFRACTORY QUALITIES OF

CONCRETES FOR JET AIRCRAFT WARM-UP, POWER CHECK,

MAINTENANCE APRONS, AND RUNI'IAYS

by

W. L. Pendergast, E« C« Tuma , L» Ea Mong

Refractories Section

Mineral Products Division

Sponsored by

Department of the Navy

Bureau of Yards and Docks

Referencej 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 STAND

i'’tended for use within the Gov<

to additional evaluation and revie

listing of this Report, either in w

the OiHce of the Director, Natlor howtver, by the Government age

le reproduce additional copies fi

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST)

on October 9, 2015.

Ily published it is subjected

reduction, or open-literature

I Is obtained In writing from

ch permission Is not needed,

jpared If that agency wishes

<NBS>

U. $. DEPARTMENT OF COMMERCE
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QUARTERLY REPORT

ON

EVALUATION OF REFRACTORY QUALITIES OF

CONCRETES FOR JET /iIRCRaFT ¥aRM-UP , PO^JER CHECK,

MAINTENANCE APRONS, AMD RUIT/LIYS

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 X-ray Examination

X-ray examination of hydrated Alcoa cement, which had

been heat treated under pressure in the bomb test and subsequently in steps to 7C0*^C in air, indicated that no detectable

change occurred in the hydrates as a result of the last heat

treatment. The results from X-ray examination from lower

heat treatments on this cement are given in Table II of

N.B.S. Report 5736. Since mercury was in contact with the

cement during the bomb test and was volatilized later at

approximately 200°C, a second bomb was charged, and the

cement, which is now being cured, will be subjected to the

bomb test without mercury. Weight losses will be obtained
t*

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,

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'
and samples for X-rays taken in the same manner as for the

first sample. This procedure should determine to what extent

the minera log ica 1 changes are accompanied by weight changes.

Samples of Portland and Lumnite cement are being heat-treated

and sampled in a manner similar to that of the first sample

of Alcoa. Some X-ray patterns have been taken, and the result

will be reported later.

2.2 Water in Concrete During Curing and Drying

In the study of the correlation of the concentration of

water with the humidity within cured concrete, a nei’j set of

tiles, five in number and four inches in depth, have been

drying at 35% relative humidity and 77°F after 28 days fogroom curing.

These tiles were cast using concrete similar in design

to that of the first series. The concrete was designed with

crushed building brick aggregate, passing No. 4 screen, seven

sacks of Portland cement per cubic yard, and a W/C ratio of

0.69. The percentages of mixing water, water gained during

curing and total water present after curing are given in

Table I.

The weight loss of the tile and the relative humidity,

at three depths from the exposed surface, have been determined

at seven day intervals. This series of tile is being studied

to indicate the causes and magnitudes of the uncontrolled

variations that were present in the first set reported in

N.B.S. Report 5736

-3-

Table I. Water Additions to Tile for Relative Humidi ty-We ightLoss Studie s

.

Specimen

Water Added During Total Water Casting Curing, 28 days

% on dry

batch weight

% on

cast weight

% on dry

batch weight

% on

cured weight

P-B - B 15.67 1,92 17 . 89 15.17

P-B - T

n 1.68 17.61 14.97

P-B - Tg // 1.77 17.72 15.05

P-B - P

it 1,50 17.40 14.82

P-B - T^ it 1.55 17 . 46 14.86

The hygrometers in the cavities nearest the exposed surface

of each tile indicated humidities above 1007o (maximum 103%)

on removal from the fog-room (at the start of the drying period).

The hygrometers near the opposite face indicated lesser values

averaging 1007o.

Some of the causes of discrepancies that appeared in the

data given for the first set of tiles have been eliminated.

Jacketing the tile by cementing the polyethelene envelope to

the five unexposed surfaces and sealing the exposed assembly

joints of the hygrometers with glyptol paint corrected many

of the discrepancies evident in Figure 1 of N.B.S. Report 5736.

Table II gives a summary of the weight loss - relative

humidity data for the second series of tile.

The relative humidities in the cavities furtherest from

the exposed surfaces were 1007o for an appreciable length of

drying time. In this respect the data is similar to that

-4-

given by Cause and Tucker— . Beyond these drying periods the

rate of decrease in relative humidity with time was constant,

for a given tile, during the total drying time of ten weeks.

Table II. Summary of Weight Loss - Relative Humidity Data,

for 3x3x4 inch Tile Dried with one 3x3 inch

Face Exposed to Air at 35% Relative Humidity and 77°F.

Spe c imen

Cavity Location Relative to Exposed Surface

Furthest Middle Neare st

Days at

100%

R.H.

Drying

Slope

% R.H.

pe r t*re e k

Days at

100%

R.H.

Drying

S lope

% R.H.

pe r we e k

Days at

10 0%

R.H.

Drying

S lope

% R.H.

pe r we e k

P-B - B 21 1.43 7 1.80 4 3 . 40

P^B - T 14 1.8 11 1.74 0 3.37

P-B - T,-^ s 14 1.7 7 1.55 0 4.07

P-B - P 21 1.17 7 1.87 0 2.57

P-B - Ty-^ 13 1.14 14

: 1,23 0 2.27

— Fabricated by different operators. —

2 / Cast 5" long, sawed to four inch dimension during curing.

Sawed surface exposed during drying.

3 / •— Upended in fog room, bottom surface as cast was exposed

during drying.

These rates were not greatly different for the different tile

even though different operators or different procedures were

used in fabricating them. The rate of change of relative

— ^ Method for Determining the Moisture Condition in Hardened

Concrete, J. of Research, National Bureau of Standards,

Vol. 25, No. 4 (October 1940).

-5-

humidities in the cavity nearest the exposed surface was

greatest for the specimen having the sawed surface exposed

and least for the specimen having the bottom surface, as

cast, exposed.

During this ten v:eek drying period, the rate of change

of relative humidity is greater in the cavity nearest the

exposed surface and grades to the smallest value in the

cavities furthest from the exposed face (one exception).

The extent of the correlation of the relative humidity

in the mid cavity with water loss for the whole specimen is

illustrated in Figure 1. This graph shows that considerable

water, amounting to approximately eight per cent of the

total water present at the end of curing (or 1,2% of the

cured weight), is lost before the humidity of the mid cavity

falls below 1007o. It is believed that the humidity in the

mid cavity approximates the average for the whole tile, but

the humidity in the cavity nearest the exposed face is less

than 100% at a much earlier time in the drying treatment

while the opposite is true for the cavity furthest from the

exposed face.

After this initial loss of v;ater, the relative humidity

in the mid cavity is inversely proportional to the water

loss as shown in Figure 1. The data indicates a linear

relation for the 10 week drying period. The slopes of the

lines are characteristic to the individual tile. The smallest

RELATIVE

HUMIDITY

WATER LOSS, PERCENT OF WATER PRESENT AT BEGINNING OF DRYING

FIGURE I WATER LOSS AND RELATIVE HUMIDITY DURING DRYI NG OF TILES,

- 6 -

slope is associated with the tile having a sawed exposed

surface which was probably more permeable. The three different

operators B, T, and P introduced differences in the properties

of the tile as indicated by the slopes of the lines.

Appearing in one of the publications listed in this

report, under Literature /_ 3 _J

,

it was concluded that if

concrete was evacuated after placing, small channels and

openings were created. This structure would be ideal to

permit the egress of steam that is generated by rapid heating

in the jet impingement test.

For comparative purposes one concrete was mixed using

a design similar to that given in N,B,S, Report 5123.

aggregate, and Portland cement. In this second batch the

maximum size of aggregate was +1/2 inch, and the ratio of

coarse to fine aggregate was reduced to 56/44. The cement

content was also reduced from seven to five sacks per cubic

yard and the IaT /C ratio increased from 0.45 to 0.62. This

change in design was made on the assumption that a wet short

mix would accentuate the beneficial effects of vacuum

processing more than would a plastic one.

This change was suggested by Mr, J. J. Creskoff, Consulting

Engineer, for Billner Vacuum Concrete, Inc,

2,3 Vacuum Processed Concrete

concrete was mixed containing the same diabase

-7-

Six test panels were fabricated using the vacuum process.

These will be exposed to our jet impingement test. Four were

fabricated using our conventional diabase aggregate concrete;

two of these four were evacuated from the bottom surface and

two from the top surface. The other two panels made from the

modified design were evacuated from the bottom surface. All

panels were evacuated for 45 minutes.

The panels made from the conventional diabase-aggregateconcrete having a W/C ratio 0.456 lost 5.6 pounds of water

when evacuated from the bottom, reducing the W /C ratio to

0.414. The panels evacuated from the top lost 3.8 pounds of

water, reducing the W /C ratio to 0.428.

The modified concrete having a W/C ratio of 0.618 evacuated

from the bottom lost considerable more, or 7.6 pounds of

water, which reduced the ’'^/G ratio to 0.480 .

A vacuum of 23 inches of mercury column was obtained when

evacuating from the bottom of the panel. The vacuum obtainable

when evacuating from the top of the panel was considerably

less, 12 inch of mercury column. This difference in the

obtainable vacuum was due to the greatly different distances

from the evacuating mat to free atmosphere.

The six panels have been cured and are undergoing drying

treatment preparatory to testing.

- 8 -

Li te rat ure

A review of the following articles was made during this

quarter.

rir/ Investigation of Vacuum Treatment of Mass Concrete

Surfaces. Technical Memorandum No. 6-353, Conducted

for Office Chief of Engineers by Waterways Experiment

Station, Vicksburg, Mississippi.

Summary

A description of the vacuum process.

Vacuum Processes Concrete, United States Department of

the Interior, Bureau of Reclamation, Materials

Laboratories Report No. C-232.

Summary

Field experience has shown the vacuum process to be

practical. The process does not interfere with nor

delay normal operations in concrete placing. The

ordinary form generally used in concrete placing

is sufficiently rigid and tight. Laboratory tests

indicated that concrete of a superior quality could

be obtained by the vacuum process due principally

to the reduction of the water content. This

reduction was effective to depths of three inches.
I.
9-

jTSj Current Applications of Vacuum Concrete, United

States Department of Interior, Bureau of Reclamation,

Concrete Laboratory Report No* C-355.

Summary

This report is not particularly pertinent to the

project. However, a statement on page 2, paragraph 5

was of interest, "...small channels and openings

created by the vacuum process."

r^j Vacuum Processes Applied to Precast Concrete Houses,

K. P. Billner and Bert M. Thorud, J . A. C . I ., Vol . 21,

No . 2 * Summary

Not pertinent to this project.

rsj7 structure and Physical Properties of Hardened Portland

Cement Paste. T, C. Powers, J*A.C.S,, Vol. 41,

No. 1 (January 1958).

Summary

Methods of studying the submioroscopic structure of

Portland cement paste are described, and deductions

about structure are presented. The main component,

cement get, is deposited in water-filled space

within the visible boundaries of a body of paste.

- 10 -

Space filled with gel contains gel pores; space not

filled by gel or other solid material is capillary

space. Hygroscopic ity of cement gel, and capillary

pores, accounts for various aspects of the properties

and behavior of concrete. Data on gel and paste

structure are used in discussing strength, permeability,

volume stability, and action of frost.

Confers nee

A conference was held at this Bureau, January 26 , The

names of those attending follow:

P. P. Brown

Melvin Herman

r. Bureau of Yards and Docks

P. Knoop

L. A. Palmer

W, L. Pendergast

S. Zerfoss

National Bureau of Standards

The object of the conference was to discuss a suitable

design for concrete to be used in fabricating test cells for

jet engines and prepare specification based on the work

completed for the aggregate to be used in the concrete. A

brief review of the work accomplished during the first nine

months of the fiscal year was reported and discussed.

Approved;

USCOMM-NBS-DC
1r\f
U. S. DKrAHTMKNT OF COMIMERCK

Sincliiir Weeks. Sccrrltiry

NATIONAL HIIKEAII OF STANDAlinS

A. V. Astiii, Dirvclor THE ^ATIOrSAL BUREAU OF STANDARDS

'I’lie scope of activities of the National Bureau of Standards at its headquarters in Wasliington,

D. C., and its major laboratories in Boulder, Colo., is su<if;ested in the following listing of the

<livisions and sections engaged in technical work. In general, each section carries out sj>ecialized

research, development, and engineering in the field indicated by its title. A brief description of

the activities, and of the resultant publications, appears on the inside front cover. WASHINGTON, D. C.

Electricity and Electronics. Resistance and Reactance. Electron Devices. Electrical Instru- ments. Magnetic Measurements. Dielectrics. Fhigineering Electronics. Electronic Instrumentation, Electrochemistry.

Optics gnd Metrology. I’hotometry and Colorimetry. Optical Instruments. Photographic

Tecfmology. Lengtii. Engineering Metrology.

Heat. Temperature Physics. riiermodynamics. (Cryogenic Physics. Rheology. Engine

Fuels. Free Radicals Research.

Atomic and Radiation Physics, Spectroscopy. Radiometry. Mass Spectrometry. Solid State Physics. Electron Physics. Atomic I’hysics. Neutron Physics. Nuclear Physics. Radioactivity. X-rays. Betatron. Nucleonic Instrumentation. Radiological Equipment.

Chemistry. Organic ('oatings. Surface (Ihemistry. Organic (diemistry. Analytical Chemistry. Inorganic Chemistry. Electrodeposition. Molecular Structure and Properties of Gases. Physical ClMjmistry. Thermochemistry. Sped rochcmislry. Pure .Substances. Mechanics- Sound. Mechanical Instriimcnls. Fluid Mechanics. Engineering Mechanics.

Maes and Scale, (lapacity. Density, and Fluid Meters. Combustion (Controls.

Organic and Fibrous Materials. Rid)her. Textih-s. Paper. Leather. Testing and Specifications. Polymer Structure. Plastics. Dental Rest'arch. Aletallurgy. I'hermal Metallurgy, (ilnmiical Metallurgy. Mechanical Metallurgy. Corrosion.

Metal Physics.

Mineral Prorlucts- Engineering (ieramies. (ilass. Refractories. Enameled Metals, Concreting Materials. (Constitution and Mierostruclure.

Building Technology. Strnctural Engineering. Eire Protection. Air Conditioning, Heating,

a?id Refrigeration. Floor, Roof, and Wall Ccjverings. Co<les and Safety Standards. Heat

Transfer.

Applied Mathematics. Numerical Analysis, (iomputation. Statistical Engineering. Mathematical Physics.

Data Processing Systems. .SEA(] Engineering (^ronp. ('.omponenls and Techniques. Digital

(.circuitry. Digital Systems. Analog Systems. Application Engineering.

• Office of Basic Instrumentation. • Office of Weights ami Measures.

BOULDER, COLORADO

Cryogenic Engineering, (-ryogenic E<]uipineiit. (’.ryi>genic Processes. Ihoperlies of Materials.

Gas Liquefaction.

Railio Propagation Physics. U[>per Atmosphere Research. Ionospheric Research. Regular

Propagation Services. Sun-Earth Relationships. VHE Research.

Radio Propagation Engineering. Data Re<luctiou luslrumcutaliou. Modidatioii Systems.

Navigation Systems. Radio Noise. I’ropospheric Measnr<‘mcnts. 'l'r»)posphcric AnaKsis.

Radio .Systems Application Engineering. Radio Mel«*oroh>g)

.

Radi<» Slaiulards. Higlj l'’re(jueney Eh‘«‘tri«‘al Standards. Raditt Ri'«»adeas! S*'rviet‘. High

Ere<}U(;ncy iiu[)eda!ice .Standards. Calibration (amler. Mi« ro\>ave Ph\sies. M iert)w a\ ( .ireiiit Standards.