Building Materials, Third Edition

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where P = load at the limit of proportionality

A = cross-sectional area

P = maximum load to cause the failure of the specimen

L = gauge length

h = deformation at the limit of proportionality.

€!™ — „ q—X The specimen for the two sizes are shown in Fig. 4.15 (a, b). The
notches shown in Fig. 4.15 (a) and 4.15 (b) are so made as to produce a failure on 50 × 20 mm
area (Fig. 4.15 (a)) or 20 × 10 mm area (Fig. 4.15 (b)) in the radial or tangential surface as desired.
The test is conducted on a testing machine provided with suitable grips to hold the specimen.
The load is applied continuously at a constant rate of 2.5 mm per minute until the maximum
load is reached for both sizes.
The maximum load required for failure in the case of perpendicular to grain is recorded. The
load divided by the area gives the maximum tensile stress perpendicular to grain in the
concerned plane (radial or tangential).

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The test specimens for the two sizes are shown in Figs. 4.16(a) and 4.16(b). The notches shown
in Figs. 4.16 (a) and 4.16 (b) should be such as to fail the specimen in radial or tangential surface
as desired. The load is applied continuously at a constant rate of 2.5 mm per minute until the
maximum load is reached for both sizes. The maximum load required for failure is recorded.
The load divided by the width gives the maximum cleavage resistance N/mm in the concerned
plane (radial or tangential).

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