2.2 WATER ABSORPTION
AIM
To determine the water absorption of coarse aggregates as per
IS: 2386 (Part III) - 1963.
APPARATUS
i) Wire basket - perforated, electroplated or plastic coated with
wire hangers for suspending it from the balance
ii) Water-tight container for suspending the basket
iii) Dry soft absorbent cloth - 75cm x 45cm (2 nos.)
iv) Shallow tray of minimum 650 sq.cm area
v) Air-tight container of a capacity similar to the basket
vi) Oven
SAMPLE
A sample not less than 2000g should be used.
PROCEDURE
i) The sample should be thoroughly washed to remove finer
particles and dust, drained and then placed in the wire
basket and immersed in distilled water at a temperature
between 22 and 32 °C.
ii) After immersion, the entrapped air should be removed by
lifting the basket and allowing it to drop 25 times in 25
seconds. The basket and sample should remain immersed
for a period of 24 + ½ hrs. afterwards.
iii) The basket and aggregates should then be removed from the
water, allowed to drain for a few minutes, after which the
aggregates should be gently emptied from the basket on to
one of the dry clothes and gently surface-dried with the
cloth, transferring it to a second dry cloth when the first
would remove no further moisture. The aggregates should be
spread on the second cloth and exposed to the atmosphere
away from direct sunlight till it appears to be completely
surface-dry. The aggregates should be weighed (Weight 'A').
iv) The aggregates should then be placed in an oven at a
temperature of 100 to 110 °C for 24hrs. It should then be
removed from the oven, cooled and weighed (Weight 'B').
REPORTING OF RESULTS
A - B
Water absorption = ———– x 100%
B
Two such tests should be done and the individual and mean
results should be reported.
