Important characteristics of aggregates which influence the properties of resulting concrete mix are discussed as under:
Aggregate containing the constituents which generally react with alkalies in cement cause excessive expansion, cracking of concrete mix, should never be used. Suitability of aggregates should be judged either by studying its service history or by laboratory tests.
Size and shape:
The size and shape of the aggregate particles mainly influence the quantity of cement required in a concrete mix and ultimately economy of the concrete. For the preparation of economical concrete, one should use largest coarse aggregates feasible for the structure.
Type of structure
Max. Size of aggregate
|1.||Mass concrete work. i.e. dams, retaining walls, piers and abutments, etc.||40mm|
|2.||R.C.C work. i.e. beams, columns, etc||20mm|
It may be clearly noted that the size and shape of the aggregate particles influence the properties of freshly mixed concrete more as compared to those of hardened concrete.