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NATIONAL BUREAU OF STANDARDS REPORT

QUARTERLY REPORT

ON

EVALUATION OF REFRACTORY QUALITIES OF

CONCRETES FOR JET AIRCRAFT VJARM-UP, POWER CHECK,

MAINTENANCE APRONS, . AND RUNWAYS

by

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

and E, Trattner

5233

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 spe- cialized 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 Instruments. Magnetic Measurements. Dielectrics. Engineering Electronics. Electronic Instrumentation.

Electrochemistry.

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

Technology. Length. Engineering Metrology.

Heat and Power. Temperature Physiqs; Thermodynamics. Cryogenic Physics. Rheology

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. 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.

Metals Physics.

Mineral Products. Engineering Ceramics. 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. SEAC Engineering Group. Components and Techniques. Digital

Circuitry. Digital Systems. Analogue Systems. Application Engineering.

• Office of Basic Instrumentation , • Office of Weights and Measures

BOULDER, COLORADO

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

Gas Liquefaction.

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

Propagation Services. Sun-Earth Relationships.

Radio Propagation Engineering. Data Reduction Instrumentation. Modulation Systems.

Navigation Systems. Radio Noise. Tropospheric Measurements. Tropospheric Analysis. Radio

Systems Application Engineering.

Radio Standards. Radio Frequencies. Microwave Frequencies. High Frequency Electrical

Standards. Radio Broadcast Service. High Frequency Impedance Standards. Calibration

Center. Microwave Physics. Microwave Circuit Standards.
NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS REPORT

0903» 20-4428 April 15, 1957 5233

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 Ee Mong

and E. Trattner

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. 9.3/1134-C

Approved

s

Dr 0 Samuel Zerfoss

Chief, Refractories Section

IMPORTANT NOTICE

NATIONAL BUREAU OF STA

intended for use within the G

to additional evaluation and re listing of this Report, either in the Office of the Director, Nati however, by the Government a

to reproduce additional copies

igress accounting documents Approved for public release by the ally published it is subjected

Director of the National Institute of P roductlon - or open-literature

in is obtained in writing from Standards and Technology (NIST) j C h permission is not needed, on October 9, 2015. epared if that agency wishes

<NBS>

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
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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. ACTIVITIES

2.1 Concrete with Diabase Aggregate

Two test panels (18 x 18 x 6 inches); after fog- room curing for

28 days and storing at 73°F and 50 percent relative humidity for 63 and

77 days respectively, were subjected to the jet blast. The results for

these panels and two others of the same design previously reported are

given in Table 1.

When compared with the results on concretes having either White

Marsh or crushed building brick aggregate, Table 1 of NBS Report 4767,

July 20, 1956, this concrete designed with diabase aggregate appears to

have a much greater resistance to spalling in the jet blast test. The

apparent discrepancies in spalling loss, as calculated by the two methods,

may be attributed to the small values of the losses.

- 2-

Table 1

Spalling Loss of Panels During Jet Impingement

Panel

—

Drying Time Total H20 at

Time of Test

Time of

Test

|

Spalling Loss Calculated ! From Weight From Volume

days c//o min. cc cc

1 28 7.97 5 52.11 93.4

2 49 7.59 5 52.11 note”/

3 63 7.37 5 17.27 135.30

4 77 7.56 5 58.02 b/

note"'

c/

5

!

Spalling loss visible but not measurable by this method.

J?/ No visible loss. —/ Not tested.

A second batch of concrete, designed with diabase aggregate and

Portland cement, was mixed during this quarter. This mix was identical in

design with that shown in NBS Report 512S>. The water content was somewhat

lower resulting in less slump and less air content, but was still easily

placed even though it was a harsh mix. Panels (18 x 18 x 6 inches) and

prisms (16 x 4 x 3 inches) were fabricated and are being fog- room cured.

The modulus of elasticity as determined on the prisms at intervals during

this curing indicated that this concrete will develop the required

strength of 650 psi. in 28 days. The panels will be subjected to the jet

blast test after increasing intervals of storage at 73°F and 50 percent

relative humidity. This work is a check on the resistance of this

concrete to jet blast before a field service test is recommended.

-3-

2.2 Concrete Designed with Crushed Building Brick

Aggregate and High-Alumina Hydraulic Cement (Alcoa)

Using as a criteria the properties determined on two trial batches,

a final large batch was designed using crushed building brick and highalumina hydraulic (low in impurities made by Alcoa) cement. The

design of the mix and the properties of the fresh concrete follows

Ratio of coarse- to- fine aggregate 60 to 40

Proportion, by weight; Cement to coarse and to fine aggregate

1 s 2.21 s 1.47

7.61 sacks/yd of concrete

0.01% by weight of cement

O

36.3 gal/yd of concrete

5.95 gravimetric method

3.00 inches

134.78 lb/ft

3

0.41

slightly harsh; sets rapidly;

compared to conventional

concrete.

Test panels and prisms were fabricated and are being fog- room

cured. Previous tests indicated that concrete designed with this type

cement reached its approximate maximum strength in 14 days fog- room

curing. Panels fabricated from this concrete will be subjected to the

jet blast test at 7-day storage intervals after the 14-day fog- room

curing.

Cement content

Vinsol resin

Water content

Air content

Slump

Weight of fresh concrete

Water cement ratio

Remarks

-4-

2.3 Absorption and Evaporation of Water

During Curing and Drying of Concrete

The NBS Report 5120, January 1957 contained a table, "Effect of Curing

and Drying of Concrete," The last column of this table, "Non-Evaporable

Water," gave the percent water retained in the concretes after drying to

constant weight at 110°C. Note l/ referring to this column explained

that the values given for non-evaporable water did not take into consideration any carbon dioxide acquired during the curing, storing, or drying

of the concretes. Samples of these concretes have now been analyzed for

carbon dioxide concentration.*^ The samples were taken from 3x3x1}

inch tile designed with portland cement and either olivine (P-0), White

Marsh sand and gravel (P-WM), or crushed building brick aggregate (P-B).

As indicated in Figure 1 the samples represented cores taken at different

depths from the exposed surface. The method used in determining the amount

of carbon dioxide present was by weighing the absorbed CC>2 following

evolution from the sample by treatment with approximately 4N hydrochloric

acid.

17 C. M. Hunt, Concreting Materials Section

FIGURE

I.

CARBON

DIOXIDE

CONCENTRATION

-

DEPTH

O ^

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ro

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ro

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CM

CD

CM

st

CM

CM

CM

O

CM

00

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00

00

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1 L; <—o

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cH m

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ro CM

lN30H3d ‘301X010 NOOdVO

=cr CD

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- CM

O

O

DEPTH

FROM

EXPOSED

SURFACE

, M

ILLIMETERS

5-

Table 2

Carbon Dioxide Content of Cores Located at Increasing Distances from

Exposed Surface.

In order to correct the values of non- evaporable water given in the

previously mentioned table it was assumed that tiles of ail thicknesses

fabricated from the same concrete absorbed the same weight of CC^. This

assumption seemed valid since all tiles had an exposure surface of the same

area (3x3 inches). The weight of CCU absorbed by the 1-g-" thick tile was

obtained by calculating the average percentage of CO2 from data given in

table 2 or Figure 1| then multiplying this percentage by the weight of

this tile. Since the weight of CO2 present was included in the values given

for non- evaporable water (Table 1, N.B.S. Report 5120) these values were

corrected for OO2

. The original values and the corrected values appear in

Table 3

-friable 3

Non-Evaporable Water in Concrete "as Reported" and Corrected for 00?

Identification Thickness of Tile Non- Eva oorable Water

As Reported | Corrected for CO?

inches

“

y i

%

6 2.46 2.25

4 2.32 1.95

P-0 2 2.61 1.89

2.69 lo70

i 2.92 1 c48

i 2.93 0.28

2 3.37 not completed

P-B 3.13 do

i 3.30 do

12 4.28 i do

2 2.31

\

S 1 *25

P-WM 2.81 1,39

2.95 0,94 /

i * 5.3T3'1 1.62 |

This high value is probably due to an accompanying high cement

content caused by removal of all aggregate larger than one-half inch.

The results indicated that the extents of carbonation of the

concretes were considerable, especially near the exposed surfaces. It

seemed evident that carbon dioxide replaced some of the water of

hydration. This replacement began at the exposed surface and progressed

inwardly as shown in Figure 1. For the tile the penetration was such

that much of the tile was carbonated with a resulting low value of nonevaporable water. A layer of similar penetration depth constituted only

a small fraction of the total volume of the 6" tile leaving much of the

mass with a low concentration of CO? and high nort-evaporable water. The

results given in Table 3 indicates that in concrete tile of such dimensions

when exposed to atmospheric conditions the non- evaporable water depends on

the thickness of the specimen.

2.4 Relative Humidity as an Indication of the Water Present

at Different Depths from Exposed Surface of Concrete.

The miniature hygrometers that have been on order for six months have

been further delayed due to the manufacturer's material shortage. Although

this has delayed the work considerably since the hygrometers were to be

custom made, no advantages would be gained by replacing the order.

2.5 Pressure Developed in Concrete During Heating

Figure 2 is a schematic arrangement of the apparatus used in determining

pres sure- temperature data on neat cement or concrete samples. This apparatus

was designed for pressures of 1000 psi at temperatures in the vicinity of

400°C. Stainless steel parts were used throughout its construction.

Several heatings of samples were made using an apparatus similar in

design but constructed using brass fittings. The material tested in this

lower capacity apparatus was neat cement that had been cured and evacuated

to constant weight at room temperature. For these tests the voids of the

system were filled with Dow Corning silicone fluid 550. This fluid was

used to transmit the water vapor pressure of the sample to the pressure gage.

This type fluid was chosen because of its high boiling-point and low vapor

pressures at the temperatures of the test. Thermocouples were located at

the center of the specimen and on the outer surface of the bomb. One test
» :

•

/
BOMB

CYLINDER

F.

PRESSURE

GAGE

FIGURE 2

SCHEMATIC

DIAGRAM

OF

BOMB

ASSEMBLY

TEMPERATURE ,°C FIGURE 3

- 8-

was made using a heating rate of 200°C per hour. This rate was subsequently

reduced to 50°C per hour in order to obtain more complete equilibrium for

a given temperature- pressure condition.

The evacuation removed almost all of the capillary water present in

the sample at room temperature. On heating this sample it could be

expected that this equilibrium would be changed and yield capillary water

and/or a change in the character of hydration. The deviation of the

pressure-temperature curve from the steam curve, Figure 3, indicated that

some changes in the bonding of water occurred during the first heating

and cooling.

Further evidence of such changes, apparently irreversible, during

the first heating cycle were also evident by the considerably smaller

pressures developed in the second, third, and fourth heating cycles.

Figures 3 and 4. The pressure-temperature curves of the last three

heatings seemed to have inflections at approximately 175°C. These

inflections may indicate a reversible change in products formed during

the first heating cycle. This indication is also partially supported by

the differential thermal effects which also indicated an additional

change at 50°C. There was a residual pressure developed in the course

of the heating and after the completion of the test approximately 3 ml of

gas was collected from the system. This quantity was too small for gas

analysis.
.
PRESSURE

,

psi

FIGURE 4

-9-

2.6 A Study of the Mechanism by Which VJater Vapor

Travels Through Concrete.

The rates at which concrete gains and loses moisture under various

environmental conditions are important because they effect the moisture

content of the concrete at the time it is exposed to high temperatures.

A study has been undertaken* therefore* of the mechanism by which

water vapor travels through concrete. As a first step in such a study,

it is planned to compare the rate of transfer of water vapor, under low

vapor pressure heads, with the rate of transfer of neon gas under similar

pressures. Under the assumption that neon is not adsorbed in appreciable

quantities at room temperature, this comparison will make it possible to

estimate how much of the water vapor transfer is by gaseous diffusion

and how much is by some other mechanism such as movement of adsorbed water.

The rate of transfer of moisture through concrete is greatly

dependent upon the moisture conditions in the concrete, and therefore it

is necessary that the concrete be essentially in equilibrium with its

surroundings. This requires that small vapor*- pressure differentials be

employed, with the resulting requirement that measuring systems be several

times more sensitive than those employed in the study of other building

materials and under high vapor- pressure differentials.

The Jolly balance used in the Penn State- Armstrong cell, whether

using a microscope or differential transformer, is not sensitive enough

for the purpose. The differential resistance of a 2 micron nichrome wire,

as measured by a SR-4 strain gage indicator, was tried and also found to

- 10-

lack sufficient sensitivity. Four war- surplus analytical balances have

been obtained and it is planned to incorporate parts of two of these in

an apparatus. Such a system is bulky, inconvenient to operate, but will

give the necessary sensitivity.

Qualitative measurements on the rate of air transfer through several

concretes have been made to furnish information needed for selecting a

method for rate-of-gas transfer determination. Attempts were made to

develop a technique for sealing the specimens in the apparatus.

3. PLANS FOR NEXT QUARTER

1. Determine the effect of the jet blast test on concrete designed

with Alcoa cement.

2. Duplicate tests on panels designed with portland cement and

diabase aggregate for the purpose of improving confidence of data.

3. Further investigation of the properties of the diabase aggregate

significant in the resistance to spalling.

4. Increase temperatures in tests of neat cement and concrete samples

in the bomb test and identify resultant compounds by X-ray or by other

means
)4
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 basm 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.