how to find Grading of coarse aggregate


      Grading of coarse aggregate


  Apparatus and materials


1.      I.S. sieve of size 40mm, 20mm, 12.5mm, 10mm, 4.75mm, 2.36mm.

2.      Coarse aggregate

3.      Vibrator


  Procedure

1.      5 kg of coarse aggregates, arranged the set of IS sieves in order with the sieve size increasing to the top, and with pan at the bottom.

2.      Before the sieves analysis was performed the Aggregate sample has to be air dried in order to avoid lumps of fine particles and to prevent clogging of finer sieves.

3.      Sieving could be done either manually or mechanically.

4.      In the manual operation the sieve was shaken giving movements in all possible directions to give chance to all particles for passing.

5.      Fineness modulus of coarse aggregate determined.

6.      Fineness modulus is defined as the sum of the cumulative % retained on the sieves of standard series divided by 100.

7.      The fineness modulus is an empirical factor and can be looked upon as the massed average size of a sieve on which the material is retained, the sieves being counted from the finest.

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