The fine and coarse aggregates stored at the stockpile or batching plant should be periodically sampled for sieve analysis, ie the Grading Test, before bringing up to the overhead hoppers for batching purpose. When the aggregates are delivered to the stockpile on site, it usually causes segregation during unloading, no matter whether by conveyor belt beside the waterfront or end tipping by lorry.
Segregation means the fine material leaves at the top while the coarse material rolls down to the toe of stockpile. Thus, sampling should be conducted at different levels within the middle half of the stockpile and avoid sampling material at the top and bottom parts. The sample will be divided by using a riffle box to obtain a specimen for testing.