Building Materials, Third Edition

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A and B, 40 mm in diameter, the distance between centres of bearers being 150 mm. Bearer A
is supported horizontally on two bearer screws C, which carry hardened steel balls D. Bearer
B is supported on one such bearer screw and ball. The load is then applied centrally on the
specimen piece at a uniform rate of 2 kN/min through a third bearer E, also 40 mm in diameter,
placed midway between the supports upon the upper surface of the specimen S and parallel to
the supports.
The transverse strength of the specimen is given by

R = 3

3

2

WL
bd
where R = transverse strength in N/mm^2
W = central breaking load in N
L = length of span in mm
b = average width in mm of the test piece at the mid section
d = average depth in mm of the test piece at the mid section
The average of the three results (separately for saturated and dry condition) should be taken
for the purpose of determining transverse strength of sample. Any specimen giving result as
much as 15 per cent below the average value should be examined for defects.

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Three cylindrical test pieces of diameter not less than 50 mm and the ratio of diameter to height
1:2 are used to determine the tensile strength of the stone in each saturated (kept in water for
3 days at 20 to 30°C) and dry condition (dried in an oven at 105 ± 5°C for 24 hours and cooled
at room temperature). The general arrangement for testing tensile strength of stone is shown
in Fig. 3.11. Each test piece to be tested is sandwiched in between two steel plates of width 25
mm, thickness 10 mm and length equal to the length of test piece. The load is applied without
shock and increased continuously at a uniform rate until the specimen splits and no greater
load is sustained. The maximum load applied to the specimen is recorded.

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Split tensile strength, S = ƒ

2 W

dL