Building Materials, Third Edition

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or tangential plane. The test is carried 2 on a suitable testing
machine with the help of a shearing tool in rig. The
direction 2 of shearing should be parallel to the longitudinal
direction. The load is applied 2 continuously at a constant
rate of 0.4 mm per minute. The maximum load required
for shearing the area is recorded. The load divided by
the area gives the maximum shearing stress in the
concerned plane (radial or tangential) for both sizes.

„ 2ƒ2„

€——  q—X The test specimen for the two sizes
are shown in Fig. 4.14 (a, b). The cross-section of the
central portion of the specimen should be 7 × 7 mm or 5
× 5 mm for the specimen in Fig. 4.14 (a) and Fig. 4.14 (b),
respectively. The specimen is held firmly in the grips
and the suitable elongation measuring device is attached
to the gauge length. The load is applied continuously at
a constant rate of one millimeter per minute for both
sizes. Elongation is measured at suitable load intervals such that 8–10 reading are available up
to limit of proportionality. Reading is continued well beyond the proportional limit and final
reading of load at failure is recorded.

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Load elongation curves are plotted. The load and elongation at proportional limit are then
read. The various characteristics are determined by the following formulae:

S. No. Characteristic Unit Formula

1. Tensile stress at proportional limits N/mm^2

P

A

2. Tensile stress at maximum load N/mm^2

P


A

3. Modulus of elasticity in tension N/mm^29

LP

A

parallel to grain

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