Aggregate or Construction aggregate, is a broad category of coarse particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates. These inert granular materials along with water and portland cement, are an essential ingredient in concrete. This section provides a list of companies manufacturing aggregate testing equipment for classifying and evaluating construction materials in accordance with various standards. Some of the tests performed on aggregates are, grading, durability, particle shape and surface texture, abrasion and skid resistance, unit weights and voids, absorption and surface moisture. Aggregate testing equipment include riffle samplers, material splitters, sieves, sieve shakers, specific gravity testers, moisture and abrasion testing equipment.