It is the aggregate most of which is retained on 4.75 mm IS sieve and contains only so much finer material as is permitted by specification. According to source, coarse aggregate may be described as: 1  Uncrushed Gravel or Stone – it results from natural disintegration of rock. 2  Crushed Gravel or Stone – it results from crushing of gravel or hard stone. 3  Partially Crushed Gravel or Stone – it is a product of the blending of the above two aggregate.