Which material is NOT classified as coarse aggregate?

Natural sand is not classified as coarse aggregate because it falls into the category of fine aggregate. Coarse aggregates are typically defined as particles that are larger than 4.75 mm (No. 4 sieve), whereas natural sand consists of smaller particles that pass this sieve size, usually ranging from 0.075 mm to 4.75 mm in diameter.

Coarse aggregates, such as crushed stone, air-cooled blast furnace slag, and crushed gravel, are used to provide strength and stability to concrete. These materials contribute to the overall structure of the concrete mix and influence its durability and load-bearing capacity. By contrast, fine aggregates like natural sand help fill the gaps between coarse aggregates and improve workability and cohesion in the mix.