Question

In the Sieve Analysis for determining the
average grain size (grain fineness number), the
mesh number of the pan just above the pan
being considered is used as the multiplication
factor.. This is because the sand collected in a
particular sieve has the size corresponding to
the Sieve just above it. However, this rule is not
followed for the first few sieves as well as for
the pan. What is the reason?​

Answer 1

Sieve analysis is used to determine the grain size distribution of coarse-grained soils. A nest of sieves is prepared by stacking test sieves one above the other with the largest opening at the top followed by sieves of successively smaller openings and a catch pan at the bottom.

Divide the masses for each sieve (individual/cumulative) by the total dry mass before washing and multiply by 100 to determine the percent retained on and passing each sieve. Calculate the percent retained and passing each sieve to the nearest 0.1%.

Answer 2

The aggregate should be oven-dried at high temperature before sieving to prevent lump formation of the fine particles due to moisture content, which might clog the fine sieve holes.