Building Materials, Third Edition

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Volumetric shrinkage is determined on 50 × 50 × 150 mm or 20 × 20 × 60 mm specimen.
The specimen is weighed initially (usually green) and the volume determined. A suitable
vessel, half filled with water, is kept on the pan of a weighing balance and weighed. The
specimen is then completely dipped in water by means of a needle as shown in Fig. 4.7 and
weighed again. The difference of the two readings is volume of the specimen.
The specimen is taken out of the
water, wiped with dry cloth, end-coated
by immersion in hot paraffin, allowed
to air-season under room conditions
and weighed periodically until
moisture content of about 12 per cent is
reached. The volume is determined
again. The specimen is then kept in an
oven at 103°  2°C until an
approximately constant weight is
reached. After oven-drying, the
specimen is again weighed and, while
still warm, is immersed in hot paraffin-
wax bath, care being taken to remove it
quickly to ensure only a thin coating.
The volume of the paraffin-coated
specimen is determined by immersion
as before.
Volumetric shrinkage form initial condition to required dry condition

= 1r

1

VV

V

× 100 per cent of volume in original condition

Moisture content, per cent = r0

0

100



WW

W

The oven dry specific gravity = W 0 /V 0

whereW 1 and V 1 = weight and volume at initial condition (usually green)
Wr and Vr = weight and volume at the initial required dry condition at r per cent moisture
content (usually 12 per cent moisture content or oven dry condition)
W 0 and V 0 = weight and volume at the oven dry condition

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Test specimens of 20 × 20 × 50 mm sizes are cut truly radial or tangential as the case may be in
lengthwise direction.

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