APR 2 2 1958



Fire Resistance of Concrete Floors

United States Department of Commerce

National Bureau of Standards

Building Materials and Structures Report 134
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BMS3 Suitability of Fiber Insulating Lath as a Plaster Base 15^

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BMS5 Structural Properties of Six Masonry Wall Constructions 20^

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BMS9 Structural Properties of the Insulated Steel Construction Co.'s "Frameless-Steel" Constructions for Walls, Partitions, Floors, and Roofs 10f5 BMSlO Structural Properties of One of the "Keystone Beam Steel Floor" Constructions

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BMS17 Sound Insulation of Wall and Floor Constructions 20(4 Supplement to BMS17, Sound Insulation of Wall and Floor Constructions 5^

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[List continued on cover page iii]
Errata to acccanpany National Biireau of Standards Building

Materials and Structiires Report BMS I3I}. **Pire Resistance of

Concrete Floors.**

Page Ij., right colimn, section i;,6. Formula (l) should read:

tf.=j3pL-^* '10 -

Page ^, the sentence immediately above table 2 should read:

The difference between the (3 values for siliceousand calcareous-aggregate concretes was considered to be real

and may be attributed to endo thermic changes that take place

in calcareous-aggregate concretes when heated, which would tend

to increase the fire endurance.

UNITED STATES DEPARTMENT OF COMMERCE • Charles Sawyer, Secretary

NATIONAL BtJREAU OF STANDARDS • A. V. Astin, Director

Fire Resistance of Concrete Floors

Daniel S. Goalwin

(

Building Materials and Structures Report 134

Issued December, 26 1952

For sale by the Superintendent of Documents, U. S. Government Printing Office, Washington 25, D, C.

Price IS cents
Foreword

This report is one of a series issued by the National Bureau of Standards

dealing with the fire resistance of building materials and constructions. It

indicates the results in a series of tests of concrete floors.

The information is intended to aid building authorities and regulatory

groups in evaluating the fire-resistance characteristics of concrete floor constructions and to give designers and builders a basis for the selection of constructions that will meet given requirements with respect to fire resistance.

A. V. AsTiN, Director.

Contents

Page

Foreword ii

1. Introduction 1 2. Test methods 1 3. Test results 2

4. Discussion 3

4.1. Type of aggregate 3

4.2. Effect of restraining forces 3

4.3. Moisture content 3

4.4. Soffit protection 4

4.5. Joists 4

4.6. Effect of slab thickness and density " 4

4.7. General 5

5. References ^ 6
Fire Resistance of Concrete Floors

Daniel S. Goalwin

The results of eleven exploratory and four full-scale fire-endurance tests on reinforced concrete floors are given. All the slabs were monolithic and were made with gravel aggregates ; sis consisted of slabs cast to engage the tops of precast lightweight concrete joists.

The effects of moisture content, aggregate type, and sofflt protection are discussed. A

general equation for the relation between slab thickness and fire resistance for different

aggregates is proposed.

1. Introduction

The increasing use of concrete slab floors in industrial and commercial building and multiple

residential dwellings emphasizes the need for adequate fire-resistance ratings of these components.

The proper selection of fire-resistant floor material, together with a closure of vertical openings, can restrict fires in large buildings to one floor for

a considerable length of time, allowing proper

abatement measures to be taken in the rest of the

building.

This report covers the i-esult of 11 exploratory

fire-endurance tests and 4 full-scale tests on

monolitliic concrete floors made with siliceousffravel aggregates. It includes a series of tests on

reinforced slabs of 4- to 8-m. thickness tested to

determine the relationship between floor thickness

and fire resistance, as well as on a series of six 21/2"

and 3-in.-thick floors tested primarily to investigate the fire resistance of concrete floors made with

prefabricated concrete joists. Several of the tests were made to determine the fire-endurance limits

of a particular construction without regard to

other constructions; therefore, some of the data

are lacking that are essential to an over-all evaluation of the relationships between the fire endurance and such variables as the slab thickness, type

of aggregate,' strength and density of the concrete, and method and time of curing the concrete.

The specific results presented should be of interest

to laboratory workers, designers, builders, and the

writers and administrators of building codes.

2. Test Methods

The full-scale tests were made in accordance

with the American Society for Testing Materials

Specification El19-47, and the American Standards Association Standard Specifications for Fire

Tests of Building Construction and Materials, No.

A21-1942, which require that a fire exposure with

standard time-temperature relation shall be applied to the under side of a test floor having no

dimension less than 12 ft and an area of at least

180 sq ft. The specifications require that the floor

must carry a continuously applied load sufficient

to cause the maximum allowable working stress in

the structural members. The criterion of failure

! may be either (a) structural (load failure), (b)

the passage of direct flame or hot gases through

the floor, or (c) a rise of the average temperature

on the upper surface of the floor of 250° F or of the

temperature at a single point on the upper surface

of 325° F.

An average temperature rise of 1,000 deg F on

the reinforcing steel or of 1,200 deg F at a single

point on the reinforcing steel is considered critical

in these tests, inasmuch as the yield strength of

carbon steel at 1,000° F is only about half its value

at 70° F, and it decreases even more markedly as the temperature rises above 1,000° F. The standard fire-exposure temperatures specified are shown

in the various curves of test results, together with

the actual temperatures achieved. While the tests of the small floors, those suffixed with the letter A,

may be considered exploratory, every effort was

made to use the standard time-temperature curve. Loadings were in accordance with the ASA test specifications except for floors 70A, 71A, and 72A,

which were tested primarily to study the effects of

moisture content and Avere tested without load.

The floors were tested in gas furnaces. The fur- nace temperatures were achieved by means of gas

burners in the furnace below the test floor. Temperature measurements were obtained with 12

chromel-alumel thermocouples in the large fur- nace and 6 in the small furnace, symmetrically ar- ranged and encased in iron protection tubes. The

temperature of the upper surface of the floors was

measured by means of thermocouples placed on

top of the floor and protected against radiation

and convection effects by 6- by 6-in. dry feltedasbestos pads 0.4 in. thick. In some of the tests thermocouples were also embedded at various

points within the floor construction.

The loads on the floors were selected to cause the

maximum allowable stress in the test members and

varied from about 40 to 80 Ib/ft^.

The floor deflections were measured during the

tests to obtain a quantitative measure of load fail- ure or an indication of approaching load failure.

Deflection measurements when made were by

means of weighted wires running over a pulley

sj'stem to the outside of the test structure, where

pointers were read against graduated scales.

Curing of the floors was in two stages : during

the first stage, the floors were covered with burlap

and kept wetted; during the second stage, the

floors were heated from underneath, the furnace

temperature varying in different tests from 100°

226506—52 1
Table 1. Suninianj of fire-endurance tests of reivforced-concrete floor constructions ^

Floor

or slab

25A

2,iA

27A

29A

30A

31A

35 A

38A

70A

71A

-72A

37

47

48

49

Construction 2

Thickness

4

3K

4

5

6

6

2M

3

Figure

number

1 (25A)

Type

Monolithic slab.

.do.

2 (71A)

2

2 (71A)

{Monolithic slab plus

M-in. gypsum plaster on lath on undcrface. Monolithic slab

.....do...

do

.....do

.do.

Slab on precast concrete joists: embed- ment 1-in., spacing

36 in.s do.—-

do

Slab cast monolithic with beams and

girders.

Slab on precast concrete joists; thin portion, embedment 3^

in., spacing 2 ft 5 in.; thick portion, em- bedment 1 in., spacing 2 ft 10 in.

5

Slab on precast concrete joists with ceil- ing of H-in. gypsum

wallboard: 1-in. embedment, spacing 3

ft.s Slab on precast concrete joists (same as 48 but no soffit protection and rein- forcement placed

higher in joists).'

Concrete

Mix ce- ment :sand: aggregate, by volume

Compressive

strength

1:2;4

1:2^:4^

1:2:4

1:2:4

1:2:4

1:2:4

1:2:4

1:2:4

l:3i^:4K

[:3M

pst

2, 370

3,000

2, 810

2, 830

1,790

2, 020

2,500

2,500

2, 500

2,100

4, 750

2,7^0

2,740

Thickness

protect- ing rein- forcement

1

^4 (bars

laid on

lath).

1

1

1

14

'AA

\A (thin

portion)

.

1 1 (thick

[ portion).

A

Reinforcement

Size

A.

(6-gage

wire

fabric)

.-.do.....

...do.....

6-gage

wire

fabric.

...do.

Spacing

7

7

7m

6

4K

4>^

Test data'

Fig- ure number

10

10

Age

Days

30

30

28

38

32

33

33

33

30

41 150

26

21

28

28

Fire

intensity

Percent

95

103

96

98

103

95

100

96

93 100

100

83

93

90

Failure <

Criterion

(Steel temperature

Surface temperature. Load

(Temperature

(Load

[Steel temperature

\ Surface tem.perature

.

[Load... (Temperature

(Load

(Steel temperature <Load

(Surface temperature. (Load.

(Temperature

(Steel temperature

•{Load

(Surface temperature.

[Steel temperature sLoad

(Surface temperature. Temperature

do

.....do

.....do

I

Steel temperature

Surface temperature i Average surface tem

perature.

Spalling

Spalling...

Load

Steel temperature

Surface temperature. Load

Time

Ar min

1 27

1 34

1 46

1 13

1 15

1 10

1 21

1 41

1 00

0 43 0 50

2 38

3 08

3 27

6 00 7

0 34

0 57 s

0 44

0 48 0 57

1 Floors 37, 47, 48, and 49 were 13H by 17 ft in horizontal area; all the others were 4J-2 by 9 ft.

2 All slabs were of gravel aggregate. Potomac River gravel mineral content: vein quartz 21%, quartzite 38%, sandstone 23%, chert 12%. Potomac River sand mineral content: vein quartz 90%, mica 4%.

3 All floors, except 70A, 71A, and 72A, were loaded to 20,000-psi nominal stress. These three were not loaded.

* All failures by temperature rise were by average rise on unexposed surface, unless otherwise indicated.

' The tensile reinforcement in the joists consisted of 0.5-Ln.-diam deformed bars, the compressive and web reinforcement of 0.265-in.-diam rods. The strength

of concrete in joists was 2,290 psi; deflection 0.42 in. at 162 lb/linear ft; yield load, 415 lb/linear ft.

6 At one point only.

' No failure of beams at 6.0 hr.

8 Temperature rise limit not reached at 1 hr 10 min.

to almost 250° F. The total curing time ranged

from 21 to 41 days, with one exception.

The monolithic constructions were made with

siliceous aggregates from I/2 to li^ in. maximum

size. Proportions of the mixes are given in table 1. The full-scale floors, 37, 47, 48, and 49, were

about 131/2 ft wide by 17 ft long. Smaller floors

about 41/2 ft wide by 9 ft long were also tested to

provide data on other variables. Construction

details of some of the floors are shown in figures 1,

2, 3, and 4 ; loading data and details of the mixes

and curinff are tabulated in table 1.

3. Test Results

The compressive strengths of control cylinders

were measured at the end of the curing period

j for each of the floor slabs; the data are given in

table 1. Compressive strengths of the prefabricated joists used in floors 47 through 49 and 70

A

through 72A are also given in table 1. Timetemperature curves for some of the slabs are given "

in figures 5, 6, 7, and 10. Each of the graphs [ shows the standard, maximum, and average fur- nace temperatures, the average and maximum

2
temperatures of the slab top, and, in some cases, the average and maximum temperatures in the

principal reinforcement. Figures 8, 9, 11, and 12

show the condition of some of the specimens befoi'e and after test. The fire intensity, defined as the

ratio of actual temperatures to standard temperaj tures integrated over the period of the test, is also

given in table 1.

4. Discussion

4.1. Type of Aggregate

i Deflection of a slab due to differential thermal

expansion in the material takes place in the direction of the heated surface and is, with certain simplifying assumptions, proportional to the temperature gradient through the slab, the square of a

linear slab dimension, and the coefficient of thermal expansion [1].^ As concretes made with limestone or blast-furnace slag (calcareous aggregates) in general have lower coefficients of thermal expansion than do concretes made with gravel

or quartz (siliceous) aggregates [2, 3, 4] smaller

I deflections may in general be expected for slabs of

' the former than for the latter. Menzel's data [5] on concrete walls give qualitative confirmation.

In addition, the temperature rise Avithin sili- ceous-aggregate concrete slabs will be greater than

for calcareous-aggregate concrete slabs under similar test conditions due to the higher thermal conductivity [6, 7]. Data on the thermal conductivities of concretes are scarce, but, as Avith most solid

materials, such conductivities are found to increase

Avith temperature. For clay brick, for instance,

the thermal conductivity doubles betAveen 100°

and 2,000° F.

Chemical changes also take place as the concrete

is heated. Large volume changes take place as a

result of chemical action in chert and quartz at relatively low temperatures ; these tend to aggravate

strains due to differential expansion in the structure. Chemical changes in concretes made of cal- careous aggregates are endothermic, thus tending

to retard temperature rise in the structure.

Entrapment of Avater or water vapor in the more

impervious concretes may have a deleterious effect on their fire resistance. While the moisture has a high heat capacity and consequently retards the

temperature rise, the pressures developed on heating and the resultant expansion of the water cause

additional strains in the structure and may cause

flaking or spalling. This effect has been observed

not only with quartz and chert gravel aggregates

but also with high-strength concretes in which the

aggregates were limestone or crushed firebrick [8]

.

The tests reported herein AA^ere made only on concretes of siliceous aggregates, and, with one ex- ception, Potomac River gravel of I/2- to %-in. size

j Avas used. The fire resistance on corresponding

^ Numbers in brackets indicate tlie literature references at the end of this report.

units made of calcareous or high-grade cinder aggregate concretes may be assumed to be higher

[9,5].

There is some evidence that the fire endurance

of concrete containing siliceous aggregate alone

increases slightly as the strength or impermeability of the concrete decreases. The data are not

sufficient to draAV quantitative conclusions. However, it is interesting to note that for the series of

4:-in.-thick slabs of similar construction and aging,

the failui-e by temperature rise varied from 1.22 hr

with 3,000-psi concrete to 1.57 hr with 2,375-psi

concrete, and the time of load failure varied from

1.25 hr with the 3,000-psi concrete to 1.77 hr for

the 2,375-psi concrete.

4.2. Effect of Restraining Forces

Load failure of concrete slabs subjected to the

fire test may be influenced by the type of restraint

against lateral expansion. If the floor is re- strained at the edges, the resulting stresses will ac- celerate spalling ; in an unrestrained floor, the only

expansion stresses are those due to thermal gradients in the slab. The large slabs of this series may

be considered to be partially restrained because of

light framing at the edges and the loAver temperatures toAvard the edges of the slab. The 41/2- by

9-ft floors tested in the small furnace may be con- sidered to have been entirely unrestrained except

for the negligible bearing friction at the ends and

the temperature gradient toAvard the edges. Ingberg [1] discusses the effect of restraint on fire

endurance in some detail.

4.3. Moisture Content

For most of the tests of this series, data on moisture content of the concrete at the time of test are not available. A relationship may be expected to

exist between moisture content of the concrete and

the fire endurance, higher moisture content at the

start of the fire exposure resulting in greater re- sistance to the fire. In the case of some dense

concretes, however, excess moisture content may

result in spalling as pressure is built up within

the concrete.

As the method of curing was fairly similar for

all the slabs tested, the indications are that the differences in fire resistance Avere probably not due

entirely to the variation in moisture content of the

slabs. The control slab of one of the floors, cured

in a manner typical of the entire group of floors,

decreased in weight by 3.1 percent in a drying

period of 21 days, during 14 of which it was being

heated. Another control slab showed a residual

moisture content of 4 percent at the time of the

test.Most of the floors Avere aged for 30 days and,

Avhile they were oven-heated for part of this time,

they may not have been as dry as construction that

had been in place for several years ; it is generally
considered that a concrete slab in place in a heated

building will lose most of its free moisture in from

1.5 to 2 years. In this respect, it may be interesting to compare the results of tests made on floors

of identical construction, 70A and 71A. Floor

70A, which had been heated at 100° F for 1 week

and at 150° F for an additional week, took 38 min

to reach the limiting temperature on the upper

surface at an age of 28 days. Floor 71A, which

was not oven-heated, took 60 min at an age of 39

days to reach the same limiting temperature.

Floor 71A Avas retested 11 days after the first test,

at which time it may be considered to have been

representative of a condition of extreme dryness.

In the retest, the limiting temperature was

reached in 43 min.

Menzel's data [5] on concrete wall slabs includes a retest of each slab after the initial nonload-bearing fire test. The reductions in time to reach limiting temperature in the retest as compared to the

original test ranged from 7 to 48 percent. MenzePs floors had been cured for 1 year without

auxiliary heating before the first tests.

4.4. Soffit Protection

The data in this series of tests are, with one or two exceptions, for floors without plaster. It is

recognized, of course, that the addition of a properly designed ceiling below a floor can increase the

fire resistance of a reinforced concrete slab.

In floor 48, the joists were protected by a ceiling

of i/2-in. gypsum wallboard that had been painted

with one coat of cold-water paint. Parts of the

wallboard began to fall after 15 min of exposure

to fire, and the entire wallboard had fallen by 30

min. The duration of the applied fire was 1 hr

10 min, at which time the temperature limit had

not been reached, the floor having failed under

load. Floor 49, consisting of a slab similar to that

of floor 48 but without soffit protection, failed by

temperature rise at 48 min. The ceiling thus gave

at least 20 min of additional fire protection to the

slab.

Floor 27A was protected by %-in. gypsum plaster on lath on the underface of the slab. This

31/4-in. slab failed by temperature rise at 1 hr 21

min as compared to an average failure time of 1 hr

30 min for three 4-in. slabs of the same general

construction but with no plaster protection. Load

failure occurred at 1 hr 54 min compared with an

average of 1 hr 30 min for the 4-in.-thick floors.

Other tests have shown more conclusively the

effectiveness of plaster as a fire retardant whether

applied on metal lath or directly to the concrete.

The Canadian code, for instance, allows a reduction of up to 1 in. in slab thickness if a ceiling of

%-in. gypsum plaster is used.

4.5. Joists

The precast joists of floors 47, 48, 49, 70A, 7lA,

and 72A (figs. 2 and 4, and table 1, footnote 5)

contained haydite, a burned-clay aggregate (light-

!

weight). The performance of the unprotected I joists of floor 47 could not be determined because

of early failure of the slab by spalling. In the , cases of both floors 47 and 48, the bond between j the joists and the slab was found to be broken. The , encasement of the upper part of the joists in the

!

slab was 0.5 to 1.0 in. i To prevent bond failure in floor 49, the i/4-in. I compression bars were moved 1 in. upward so as

j to be adjacent to and just inside the top of the

joist, and the joists were embedded 1 in. into the]

slab; the joist web i-ods thus served as reinforce1

ment against shear of the joists at the level of the

bottom of the slab. This also gave additional concrete protection below the steel of the joists. The

tension steel in this floor reached 1,000° F in 44

min, the upper surface of the floor reached limit1

ing temperature in 48 min, and the floor failed

'

under load at 57 min. The joists spalled only I slightly, and the bond between the joists and floor j did not fail. The unprotected joists thus have a

J fire endurance of approximately % hr, the loadcarrying ability of the joists under fire being

dependent upon the thickness of the concrete pro1

tectine the steel.

4.6. Effect of Slab Thickness and Density

j The fire endurance of a concrete slab, as determined by temperature rise only, is plotted in figure

}

13 against the slab thickness. Although the scat1

ter of the points is large, the fire endurance may j be best represented as varying with the 1.7 power i of the slab thickness. This relation of thickness 1 to fire resistance is also given in BMS92 [10]^ fori

other types of construction. I An empirical relation has been developed giving I the time for failure of a concrete slab due to 250 | cleg F temperature rise as a function of the density i of the concrete and the thickness of the slab. This

formula is

,

t;=^pL''io-^^, (1):

where tf is the time to failure hj 250 deg F temper1

ature rise, L is the slab thickness, p is the specific

gravity of the concrete ( water = 1) , and j8 is a pro-

,

portionality constant.

The validity of equation 1 for predicting the

results of fire-endurance tests has been evaluated

by calculating /3 for fire tests conducted at the Na-

'

tional Bureau of Standards and in the Portland

:

- The thermal conductivity of concrete is obtainable from data

given in reference [7] and unpublished NBS data as

p

k = a.lO:\ (•-')

where k is the thermal conductivity, a is the constant, p is the

specific gravity of the concrete.

4
Cement Association Laboratories in Chicago [5]

on 28 concrete slabs of various aggregates and

thicltnesses. Some of the slabs were tested vertically, some horizontally. The data and calculated

values are listed in table 2. In this table tf is in

hours, p is dimensionless (specific gravity), L is in inches, and /? is a constant of mixed units that

includes specific heat and the heat-transfer

coefficient.

The average value of /? for siliceous-aggregate

concrete slabs was found to be 0.74; for slabs of

calcareous aggregates, 0.96; for haydite, 1.00; and

for a mixture of siliceous and haydite aggregates,

0.87. The difference between the p values for sili- ceous- and calcareous-aggregate concretes was con- sidered to be real and may be attributed to exoTable 2. Validity of generalised fire-resistance

formula

Aggregate ' Source

of data 2 ThicknGSs, L

Specific gravity ^ p

Time to

failure, tf

Proportionality conDeviation

d> VtJl dgC

S M

in.

2. 26

Ar 1.10 0.65 0. 09 S M 6 2.24 2.50 .72 .02 s M QO

o on 00 .75 .01 s NBS 4 2.2 1.28 .72 .02 s NBS 4 2.2 1.35 .76

.80

.02 s NBS 4 2.2 1.42 .06 s NBS 5 2.2 2. 00 .76 .02 s NBS 6 2.2 2.58 .70 .04 s NBS 6 2.2 2.82 .76 .02 s NBS 8 2. 2 4. 67 . 78 . 04 s M 6 2. 25 2. 63 .75 .01 s M 6 2.24 2.50 .70

Ail .04 s M 6 2. 26 2. 38 . Uo s NBS 3 2.2 1.00 .82 .08 s NBS 3 2. 2 0.83 .70 .04

0.74 0.04

c M 4 2. 35 1.37 0. 82 .98

0.14 c M 6 2. 37 3.27 .02 c M 8 2.35 5. 52 1.00

.98 .04 c M 6 2. 45 3.02 .02 c M 6 2.40 3.27 1.00 .04

Average . 0.96 0. 05

H M 4 1. 39 2.33 0.82 0. 17 H M 68

1.38 6. 38 1.02 .02 H M 1.47 10.0 1.02 .02 H M 6 1.46 8.12 1.09 .09 H M 6 1.38 6. 38 1.02 .02

A veraffp. 1.00 0.07

SH._..

SH.___ SH--.. M

M

M

6

66

1.80

1.88

1.84

3.98

4.20

4.23

0. 83

.89

.88

0.04

.02

.01

Avp.raffe 0.87 0.02

1 S=siliceous; C=caIcareous; H=hayclite; SH=equal quantities siliceous and haydite aggregates.

2 M = Menzel (slabs tested vertically) ; NBS =National Bureau of Standards

(slabs tested horizontally).

3 Specific gravity (p) values for the NBS slabs are average values based upon measurements of representative slabs. p <0=^i-'-'lo'

P

thermic changes that take place in siliceous-aggregate concretes when heated, which would tend to

decrease the fire endurance. It may be noted that

the specific gravities of the siliceous- and calcareous-aggregate concretes were very similar.

The above (3 values were obtained from data on

typical medium-dry slabs. In accordance with

data obtained by retesting slabs after the initial

fire tests, the "bone-dry" condition may be reason- ably represented by a decrease in fire endurance

of from 10 to 35 percent. Very wet slabs may be

expected to have fire endurances not exceeding 30

percent greater than those calculated from equation 1. . = =

4.7. General

In all the tests described in this report, the fire

was applied to the underside of the floor in ac- cordance with ASA specifications for fire tests. It

is to be expected that fire conditions on the upper

side of the floor will not be as severe as on the

bottom of the slab because of convection effects,

and that the fire endurance of concrete floors Avill be as great or greater when exposed to fire from

the top as when exposed from the bottom.

The effect of reinforcement has not been investigated thoroughly. It is apparent that if the protection for the reinforcing bars is not adequate, the

temperature rise in the bars may be such as to cause failure due to decrease in yield strength, even though the temperature on top of the floor

has not risen the necessary amount to cause failure

by temperature rise. (The yield strength of car- bon steel drops rapidly as the temperature approaches 1,000° F.) Menzel [5] presents some interesting data on the temperatures within the slab,

indicating the concrete covering required under

the reinforcement for a given protection for the

steel. For siliceous sand and gravel, a concrete

covering of 1 in. mider the reinforcement in a 6-in.

slab keeps the steel temperature below 1,000° F for

11/2 hours.

The results of tests of essentially identical floors

were found to differ considerably, due in part to

uncontrolled or unreproducible variables, such as

differences in the moisture content, workmanship,

size of aggregates, density of concrete, and details

of curing and framing. The tests provide qualitative information as to the ranges of fire endurance

to be expected and the character of failure to be

encountered.

Acknowledgement is made to the various manufacturers who supplied materials and assisted in

the erection of some of the full-scale floors, to S.

H. Ingberg, N. D. Mitchell, H. D. Foster, and

other members of the Fire Protection Section Avho

planned, supervised, and conducted the tests.

5
5, References

[1] S. H. Ingberg, Size and border conditions of test specimens in their relation to results of fire tests, Proc. ASTM 49, 1065 (1949).

[2] W. H. Johnson and W. H. Parsons, Thermal expansion of concrete aggregate materials, J. Research

NBS 32, 101 (1944), RP1578.

[3] D. G. R. Bonnell and F. C. Hai-per, The thermal ex- pansion of concrete, British National Building

Studies, Technical Paper No. 7, DSIR (Building

Research Station) (1951).

[4] P. H. Peterson, Burned shale and expanded clay

concretes, J. Am. Concrete Inst. 20, 165 (1948).

[5] C. A. Menzel, Tests of the fire resistance and thermal

properties of solid concrete slabs and their significance, Proc. ASTM 43, 1099 (1943).

[6] R. AV. Kluge, M. M. Sparks, and E. C. Tuma, Lightweight-aggregate concrete, Proc. Am. Concrete

Inst. 40, 625 (1949).

[7] Lightweight aggregate concretes, U. S. Housing and

Home Finance Agency (1949).

[8] Nolan D. Mitchell, Fire tests of steel columns pro- tected with siliceous aggregate concrete. NBS

Building Materials and Structures Report BMS124

(1951).

[9] Fire grading of buildings, British Building Research

Board, Post-War Building Study No. 20 (1946).

[10] Fire-resistance classifications of building construction, NBS Building Materials and Structures Report BMS92, Report of Subcommittee on FireResistance Classifications of the Central Housing

Committee on Research, Design, and Construction

(1942).

ADDITIONAL REFERENCES

Fire-resistance and sound insulation ratings for walls,

partitions, and floors, NBS Technical Report on Building Materials 44 (1946).

H. P. Gurney and J. Lurie, Charts for estimating temperature distributions in heating and cooling solid shapes,

Ind. and Eng. Chem. 15, 1170 (1923).

G"X6"PADS0VER(6)

SURFACE THERMOCOUPL£S(S)

^'DEFORMED REINFORCING BARS IB)-^ SPACED 7"0.C. AND V*80VE EXPOSED SURFACE

THERMOCOUPLES (5) IN STEEL

TRANSVERSE BARS (4) SPACED 3Cfac. AND LAD ABOVE LONGITUDINAL RODS

6'X6"PA0S OVER (5) SURFACE THERMOCOUPLES (S)

THERMOCOUPLES (8) IN STEEL

^gDEFORMED REINFORCING BARS(6) SPACED lO'O.C. AND LAID ABOVE LATH

VSANDED GYPSUM PLASTER

3.4 LBi^" EXPANDED METAL RIB LATH

TEST NO. 25-A TEST NQ 27 -A

6 X6 PADS 0VER(5)

SURFACE THERMOCOUPLES (S)

THERMOCOUPLES (8) IN STEEL

DEFORMED REINFORCING BARS (9) SPACED 6"Qa AND I " ABOVE EXPOSED SURFACE

TEST NQ 30-A

Figure 1. ConMruction of floors 25A, 27A, and SOA.

6
6 X6 PADS OVER (6) SURFACE THERMOCOUPLES (S)

8" PRECAST HAYDITE JOISTS 36"0.C. EMBEDDED 1" IN EXPOSED SURFACE -

6X6 N06GA WELDED WIRE FABRIC

LAID >2" ABOVE EXPOSED SURFACE

TEST N0.7I-A AND RETEST N0.7I-A

Figure 2. Construction of floors 35A, S8A, and 71A.

k" DEFORMED TRANSVERSE BARS (24) PLACED

4" FROM ENDS OF SLAB AND 8'O.C. ^"DEFORMED LONGITUDINAL BARS(8)

^ 'M'STIRRUPS (19 SHOWN) SPACED AS INDICATED AND PLACED IN BOTH BEAMS

6"X 6" PADS OVER

SURFACE THERMOCOUPLES (S)

I !4",4", AND FOUR 6" INTERVALS FROM EACH END OF GIRDER

2"X2"MESH(N0T SHOWN) / PLACED IN THIS BEAM ONLY '

VOEFORMED BARS PLACED AS

SHOWN e BARS IN EACH BEAM

THERMOCOUPLES IN STEEL INDICATED BY SMALL CIRCLES(o)

^"DEFORMED BARS (2) AT TOP OF GIRDER ^g'DEFORMED eARS(7) IN LOWER PART OF GIRDER

TEST NO. 37 Figure 3. Construction of floor 37.

7
6 X6 PADS OVER

SURFACE THERMOCOUPLES {SI

DOUBLE STRAND 16 GA WIRE TIES

S'XS'NOSGA WIRE FABRIC PLACED '/{FROM EXPOSED SURFACE OVER ENTIRE FLOOR

2'X2' YELLOW PINE FURRING STRIPS SPACED 16" D C.

^8" PRECAST HAYDITE JOISTS EMBEDDED I" IN EXPOSED SURFACE

'.^"GrPSUM WALLBOARD FASTENED TO FURRING

STRIPS WITH Gd CEMENT COATED l3l^GA BOX NAILS iT'gLONO

'4" DIA HEADS. NAILS SPACED 6" O.C

TEST NO. 48

FiGtTEE 4. Construction of floor 48.

-- 1300

1200

= -1100

400

2 3 4 5 ' 6 7 TIME, HOURS

FiGUKE 5. Surface, steel, and f urnace temperatures for floor 37.

a.
ZD

trLd

D1300

1200

1100

--I000

800

600

--500

300

= -200

= -100

Oo , UJ

cc

01UJ

Q.

LU

TIME, HOURS

Figure 6. Surface,

steel, and fur- nace temperatures for floors 27A, 30A, and,

35A.

Figure 7. Surface, steel, and

furnace temperatures for

floor 38A.

UJ

CC

cr

UJ

CL

LlJ

-1300

-1200

1100

1000

900

800

700

-600

500

400

300

100

oo , UJ

<r

crUJ

a.

2 3

TIME, HOURS
FiaXJEE 8. Floor 47 after test showing holes in zy^-in. slaT) formed iy spalling.

FiGiTKE 9. Detail showing shear failure between joist and

3-in. slai of floor Jp.

LJtr

UJQ.

2400

2300

2200

2100

2000

1900

1800

1700

1600

1500

1400

1300

1200

1100

1000 900

800

700

600

500 400

300

200

100

0

TEST NO. 71-A TEST NO. 49

U

Q

1U

u

c0

c.

i c

:

5»

: 9

F MAX FMAX

REFERENCE CURVE

> >

'''

'

^REFERENCE

CURVE

/

/>

7

/

% ( 1 STEEL MAX.

il

(

I ' V

1 1

f

k f

—

,

STEEL

'FRISE59MIN

30SEC. 1

GAS0FF58MIN

/ f

250'F

RISE

48MIN

SMAX~

'

(

Oin

S MAx^

c

'

\

1300

1200

HOC

1000

900

800

700 LU

CE

CE

UJ

600

500

100

UJ

(-

TIME. HOURS

Figure 10. Surface, steel, and furnace temperatures for floors 71A and ^9.

10
oa

Z)o

X

z

tiJ o

z

CO

cn

cc

I

I

A

/

3 4 5 6789 10 FLOOR THICKNESS IN INCHES

Figure 13. Fire resistance, tf, as a function of slai thick- ness, L (log-log plot).

Vertical lines show range of data ; circles show average fire endurance for a given thiclcness. The solid line, 1.7 power, gives the best linear fit ; the dashed line shows that a 2.0 power might

also conceivably fit the data. Washington, October 6, 1952.

U. S. GOVERNMENT PRINTING OFFICE: 1952 11



BUILDING MATERIALS AND STRUCTURES REPORTS

[Continued from cover page ii] BMS34 Performance Test of Floor Coverings for Use in Low-Cost Housing: Part 1 15^

BMS36 Structural Properties of Wood-Frame Wall, Partition, Floor, and Roof Constructions With "Red Stripe" Lath Sponsored by The Weston Paper and Manufacturing Co 10(J BMS38 Structural Properties of Two "Dunstone" Wall Constructions Sponsored by the

W. E. Dunn Manufacturing Co lOfi BMS39 Structural Properties of a Wall Construction of "Pfeifer Units" Sponsored by the

Wisconsin Units Co 10j5

BMS43 Performance Test of Floor Coverings for Use in Low-Cost Housiug: Part 2 150

BMS44 Surface Treatment of Steel Prior to Painting lOjS

BMS47 Structural Properties of Prefabricated Wood-Frame Constructions for Walls, Partitions, and Floors Sponsored by American Houses, Inc 20(6 BMS48 Structural Properties of "Precision-Built" Frame Wall and Partition Constructions

Sponsored by the Homasote Co 15f5 BMS50 Stability of Fiber Building Boards as Determined by Accelerated Agiag 100

BMS51 Structural Properties of "Tilecrete Type A" Floor Construction Sponsored by the

Tilecrete Co 100

BMS52 Effect of Ceiling Insulation Upon Summer Comfort 150

BMS53 Structural Properties of a Masonry Wall Construction of "Munlock Dry Wall Brick"

Sponsored by the Munlock Engineering Co 100

BMS54 Effect of Soot on the Rating of an Oil-Fired Heating Boiler 100

BMS55 Effects of Wetting and Drying on the Permeability of Masonry Walls 100

BMS58 Strength of Soft-Soldered Joints in Copper Tubing 100

BMS60 Strength, Absorption, and Resistance to Laboratory Freezing and Thawing of Building

Bricks Produced in the United States 300

BMS62 Structural Properties of a Precast Joist Concrete Floor Construction Sponsored by

the Portland Cement Association 150

BMS63 Moisture Condensation in Building Walls 150

BMS65 Methods of Estimating Loads in Plumbing Systems 150

BMS66 Plumbing Manual 350

BMS67 Structural Properties of "Mu-Steel" Prefabricated Sheet-Steel Constructions for

Walls, Partitions, Floors, and Roofs, Sponsored by Herman A. Mugler 150

BMS68 Performance Test for Floor Coverings for Use in Low-Cost Housing: Part 3 200

BMS69 Stability of Fiber Sheathing Boards as Determined by Accelerated Aging 100

BMS70 Asphalt-Prepared Roll Roofings and Shingles 200

BMS71 Fire Tests of Wood- and Metal-Framed Partitions 200

BMS72 Structural Properties of "Precision-Built, Jr." Prefabricated Wood-Frame WaU Construction Sponsored by the Homasote Co 100

BMS73 Indentation Characteristics of Floor Coverings 100

BMS74 Structural and Heat-Transfer Properties of "U. S. S. Panelbilt" Prefabricated SheetSteel Constructions for Walls, Partitions, and Roofs Sponsored by the Tennessee

Coal, Iron & Railroad Co 200

BMS76 Effect of Outdoor Exposure on the Water Permeability of Masonry Walls 150

BMS77 Properties and Performance of Fiber Tile Boards 100

MBS78 Structural, Heat-Transfer, and Water-Permeability Properties of Five Earth-Wall

Constructions 250

BMS79 Water-Distributing Systems for Buildings 200

BMS80 Performance Test of Floor Coverings for Use in Low-Cost Housing: Part 4 150

BMS81 Field Inspectors' Check List for Building Constructions (cloth cover, 5x7}^ inches). 300

BMS82 Water Permeability of Walls Built of Masonry Units 250

BMS83 Strength of Sleeve Joints in Copper Tubing Made With Various Lead-Base Solders 150

BMS85 Dimensional Changes of Floor Coverings With Changes in Relative Humidity and

Temperature 100

BMS86 Structural, Heat-Transfer, and Water-Permeability Properties of "Speedbrik" Wall

Construction Sponsored by the General Shale Products Corporation 150

BMS87 A Method for Developing Specifications for Building Construction—Report of Subcommittee on Specifications of the Central Housing Committee on Research,

Design, and Construction 200

BMS89 Structural Properties of "Precision-Built, Jr." (Second Construction) Prefabricated

Wood-Frame Wall Construction Sponsored by the Homasote Co 150

BMS90 Structural Properties of "PHC" Prefabricated Wood-Frame Constructions for Walls,

Floors, and Roofs Sponsored by the PHC Housing Corporation 150

[List continued on cover page iv]
BUILDING MATERIALS AND STRUCTURES REPORTS

[Continued from cover page iii] BMS92 Fire-Resistance Classifications of Building Constructions 30^

BMS94 Water Permeability and Weathering Resistance of Stucco-Faced, Gunite-Faced, and

"Knap Concrete-Unit" Walls 15^

BMS95 Tests of Cement-Water Paints and Other Waterproofings for Unit-Masonry Walls 25^

BMS96 Properties of a Porous Concrete of Cement and Uniform-Sized Gravel 10^

BMS99 Structural and Heat-Transfer Properties of "Multiple Box-Girder Plywood Panels" for

Walls, Floors, and Roofs 15^

BMSlOO Relative Slipperiness of Floor and Deck Surfaces 10^

BMSlOl Strength and Resistance to Corrosion of Ties for Cavity Walls 10^

BMS102 Painting Steel 10^

BMS103 Measurements of Heat Losses From Slab Floors 15^

BMS104 Structural Properties of Prefabricated Plywood Lightweight Constructions for Walls,

Partitions, Floors, and Roofs, Sponsored by the Douglas Fir Plywood Association. _ 30(S BMS105 Paint Manual With Particular Reference to Federal Specifications $1. 25

BMS106 Laboratory Observations of Condensation in Wall Specimens lOji

BMS108 Temperature Distribution in a Test Bungalow With Various Heating Devices 150

BMS109 Strength of Houses: Application of Engineering Principles to Structural Design $1.50

BMSllO Paints for Exterior Masonry Walls 150

BMSlll Performance of a Coal-Fired Boiler Converted to Oil 150

BMS112 Properties of Some Lightweight-Aggregate Concretes With and Without an Air-Entraining Admixture 100

BMS1 1 3 Fire Resistance of Structural Clay Tile Partitions 150

BMS114 Temperature in a Test Bungalow With Some Radiant and Jacketed Space Heaters 250

BMS115 A Study of a Baseboard Convector Heating System in a Test Bungalow 150

BMS116 Preparation and Revision of Building Codes 150

BMS117 Fire Resistance of Walls of Lightweight Aggregate Concrete Masonry Units 200

BMS118 Stack Venting of Plumbing Fixtures 150

BMS119 Wet Venting of Plumbing Fixtures 200

BMS120 Fire Resistance of Walls of Gravel-Aggregate Concrete Masonry Units 150

BMS121 Investigation of Failm-es of White-Coat Plasters 250

BMS122 Physical Properties of Some Samples of Asbestos-Cement Siding 150

BMS123 Fire-Tests of Wood-Framed Walls and Partitions With Asbestos-Cement Facings 150

BMS124 Fire Tests of Steel Columns Protected With Siliceous Aggregate Concrete 150

BMS125 Stone Exposure Test WaU 300

BMS126 The Self-Siphonage of Fixture Traps 200

B MS127 Effect of Aging on the Soundness of Regularly Hydrated Dolomitic Lime Putties 150

BMS128 Atmospheric Exposure Tests of Nailed Sheet Metal Building Materials 200

BMS129 Fire Endurance of Shutters for Moving-Stairway Openings 100

BMS130 Methods and Equipment for Testing Printed-Enamel Felt-Base Floor Covering 150

BMS131 Fire Tests of Gunite Slabs and Partitions 150

BMS1 32 Capacities of Plumbing Stacks in Buildings 200

BMS133 Live Loads on Floors in Buildings . 200

BMSI34 Fire Resistance of Concrete Floors 150

1





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