Some kind of filler materials are used in Concrete or mortar to increase its volume, these are termed as aggregates. They may be naturally obtained, manufactured in plant or by-product of other industries. Aggregate are main mass composition of concrete and posses about 70-80% of concrete.
Aggregates may be Natural or Artificial depending upon their geologic origin.
But mainly what we are used to classify them is according to their Size.
They may be Coarse aggregate and Fine Aggregate as per their size-
Aggregate having size greater than 4.75 mm to 80 mm are coarse aggregate. Usually for concreting 20 mm and 10 mm size aggregate are used as coarse aggregate.
Aggregate having size less than 4.75 mm but not less than 0.06 mm are fine aggregate. Fine aggregate are also classified as Fine, Medium and Coarse fine aggregate.
IS: 383 specifies four zones of grading according to the size of fine aggregate.
On the Basis of shape – aggregate are of round, angular, flaky and etc.