Concrete aggregate is made up of fine and coarse aggregates. Fine aggregates are natural sand or crushed stone where most particles are smaller than 5 mm. Coarse aggregates are a combination of gravels or crushed aggregate with particles mostly larger than 5mm, and generally between 10 mm and 40 mm.
Crushed Stone -
Crushed stone is the product resulting from mechanically crushing rocks, boulders, or large cobblestones. Crushing produces faces, which possess well-defined edges that are desirable for good concrete. Crushed stone comes in a variety of graded sizes depending on the desired application, such as road base, drainage, concrete mixes, or decorative stone.
Sand is a fine mineral that is found naturally due to the erosion of sandstones, or can be manufactured by processing sandstone or rock with similar qualities. It has a particle size passing the 9.5 mm (3/8”) sieve and almost passing the 4.75 mm (No. 4) sieve. Sand is mostly retained on the 75 µ m (No. 200) sieve. Sand is commonly used as a component of concrete, to enable water drainage, or to provide stability under concrete slabs, sidewalks, and driveways.
Gravel is a granular mineral found naturally in water-borne geological deposits, or it can be manufactured by crushing rock. Gravel is the material mostly retained on a 4.75 mm (No. 4) sieve. Gravel is a common component of concrete, but is also often used in road base, as backfill, or to support utility piping.