Aggregates that occupy nearly 70 to 75 percent volume of concrete have big role in strength of cement concrete. Physical, chemical and thermal properties of aggregates influence the properties and performance of concrete. Proper selection of Construction aggregates is important considerations, both economically as well as technically.
There are two types of aggregates (Building material) Fine aggregate and coarse aggregate.
An aggregate, which passes through 4.75mm IS sieve and is retained on 75 micron IS sieve is known as fine aggregate. Fine aggregate shall consist of natural sand, crushed stone sand or crushed gravel sand stone dust, marble dust, fly ash and surkhi. It shall be hard, durable, chemically inert, clean and free from adherent coatings, organic matter etc.
Coarse aggregate is natural gravel, crushed stone etc. The most part of it retained on 4.75mmIS sieve and contains only as much fine as is permitted in IS;383-1970 for various sizes and grading. It shall be hard, strong, dense, durable, chemically inert, clean and free from adherent coatings, organic matter etc. It shall be roughly cubical in shape. Flaky and elongated piece shall be avoided. Coarse aggregate shall not contain any material liable to attack the steel reinforcement. The maximum quantity of deleterious material shall not be more than 5 percent of the weight of the aggregate in accordance with IS2386, part2-1963.