Building Materials, Third Edition

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From the sample of coarse aggregate, sizes finer than 4.75 mm are removed and the size of
sample for different sizes should be as follows.

Size (mm) Yield (g)

(square hole sieve)

10 to 4.75 300

20 to 10 1000

12.5 to 10 (33%)

20 to 12.5 (67 %)

40 to 20

25 to 20 (33%) 1500

40 to 25 (67%)

63 to 40

50 to 40 (50%) 3000

63 to 50 (50%)

80 or more 3000

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In case of fine aggregate, these are thoroughly washed on a 300 micron IS sieve and dried to
constant weight at 105 to 110°C and separated into different sizes by the set of sieves listed
earlier to yield at least 100g each. The coarse aggregate sample are washed thoroughly and
dried to constant weight at 105 to 110°C and separated into different sizes. Particles coarser
than the 20 mm IS sieve are counted.
The aggregate sample is immersed for 16 to 18 hours in the prepared solution of either
sodium sulphate or magnesium sulphate solution. The sample is maintained at 27 ± 1°C. The
aggregate sample is then removed from the solution and drained for 15 ± 5 minutes, placed in
drying oven at 105-110°C and dried to constant weight. The sample is allowed to cool to room
temperature. The process of immersion and drying is repeated for as many number of cycles
as agreed to between the purchaser and vendor. The sample is then examined for quantitative
and qualitative examination.

——2/—— X After the completion of final cycle the cooled sample is washed free
from the sodium sulphate or magnesium sulphate with barium chloride. Each sample is dried
to constant weight at 105 - 110°C and weighed. Fine aggregate are sieved over the same sieve
on which it was retained before the test, and coarse aggregate over the following sieves.

Size of aggregate (mm) Sieve used to determine loss (mm)

10 to 4.75 4

20 to 10 8

40 to 20 16

63 to 40 31.5

——2/—— X Frations of samples coarser than 20 mm are examined qualitatively
for each immersion as well as at the completion of the test. The effects observed may be classed
as disintegration, splitting, crumbling, cracking, flaking, etc.