Aggregates are raw materials that are produced from natural sources and extracted from wells and quarries, such as gravel, crushed stone and sand.
Aggregateis a term given to a collection of granular building materials used to create concrete slabs and form surfaces and substrates. It is commonly used in residential and commercial projects for its economic factor, to reduce cracks, and most importantly, to provide strength to the structure. During the Roman Empire, there was a significant refinement of the production and use of aggregates, which were used to build its vast network of roads and aqueducts.
Both coarse-grained aggregates (particle sizes from 20 mm to 4 mm) and fine aggregates (particle sizes less than 4 mm) are required, but the proportions of the different sizes of coarse-grained aggregates will vary depending on the particular mixture required for each individual end use. The exposed aggregate is prepared and poured in a manner similar to concrete, however, the top surface is removed after a few hours of setting to expose the material underneath. Unpaved roads and parking areas are covered by a surface layer of aggregate to provide a more solid surface for vehicles, from bicycles to trucks. These include all types of fine and coarse-grained aggregates, which are available in almost ready-to-use form, from natural resources.
This polystyrene, otherwise intended for landfill, is collected, melted, mixed, reformulated and expanded to create low density aggregates that maintain high strength properties under compressive loads. The use of glass aggregate helps close the cycle in glass recycling in many places where glass cannot be melted into new glass. For greater workability and economy, as reflected in the use of less cement, the fine aggregate must have a rounded shape. Specialized aggregates are required for use in certain demanding applications, especially when lightweight members are required in constructions or when heavy, high-density materials are required.
When specifying void graded aggregates, certain particle sizes are omitted from the aggregate of the size continuum. Aggregates are a very critical and important component of high-density concrete and are mainly crushed minerals that contain relatively heavy elements, in combination with various additives, but can also include scrap steel or certain ceramics. Therefore, aggregates need to have a low density and weight, achieved through the use of porous materials, but adequate strength.