Building Materials, Third Edition

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dry condition by drying them in an oven at 105 ± 5°C for 24 hours and then cooled in a
desiccator to 20–30°C. These are tested in universal testing machine. The load is applied gently
at a rate of 14 N/mm^2 per minute until the resistance of the specimen piece to the increasing
load breaks down and no greater load is sustained.
The compressive strength of the specimen piece is the maximum load in Newtons supported
by it before failure occurs divided by the area of the bearing face of the specimen in mm^2. The
average of the three results in each condition separately should be taken for the purpose of
reporting the compressive strength of the sample.
When the ratio of height to diameter or lateral dimension differs from unity by 25 per cent
or more, the compressive strength is calculated by the following expression.

Cc =

 



Cp

0.778 0.222 b

h

where Cc = compressive strength of standard specimen piece
Cp = compressive strength of the specimen having a height greater than the diameter
or lateral dimension
b = diameter or lateral dimension
h = height
The crushing strength of stones varies in the range of 15–100 N/mm^2.

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2ssAAX To test stone for transverse strength, specimen
pieces are made in the form of blocks 200 × 50 × 50 mm. These are tested in saturated and dry
conditions similar to as explained in the compressive strength test. Test apparatus used for
testing is shown in Fig. 3.10. Each specimen piece is supported upon two self-aligning bearers

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