Aggregates are defined as a mass or body of rock particles, mineral grains, or a mixture of both. They encompass various hard, inert materials such as sand, gravel, crushed stone, and slag. These materials can be used alone or mixed with cement or bituminous substances to create concrete, mortar, or plaster. In geology, aggregates primarily refer to the natural and man-made materials extracted for construction purposes.[6][7]
Types
Aggregates can be classified into several categories based on their origin and physical characteristics.
Natural aggregates
Natural aggregates include materials like sand and gravel that are extracted directly from the earth. They can be formed through geological processes such as erosion, sedimentation, and glaciation.
Manufactured aggregates
Manufactured aggregates are produced by crushing larger rocks into smaller pieces. Common examples include crushed stone and recycled concrete.
Coarse aggregates
Typically retained on a 4.75 mm sieve, coarse aggregates include larger stones and gravel.
Fine aggregates
Passing through a 4.75 mm sieve, fine aggregates consist of sand or smaller particles that fill voids in coarse aggregates.[8]
Lightweight aggregates
Lightweight aggregates are made from materials such as expanded clay or pumice and are used to reduce the overall weight of concrete structures.
The geological formation of aggregates is influenced by various geological processes. Over time, natural forces such as wind and water erodebedrock, leading to the creation of sand and gravel deposits. These materials sediment in riverbeds, lakes, and coastal areas.
The distribution of aggregates is often determined by geological investigations that assess the location and nature of potential aggregate deposits in an area.[9][10]
Importance in construction
Aggregates play a crucial role in construction due to their mechanical properties. They provide strength and stability to structures such as roads, bridges, and buildings. In concrete production, aggregates account for about 60% to 80% of the total volume. Their presence enhances the durability and workability of concrete mixes. Aggregates also serve as a low-cost extender for more expensive materials like cement or bitumen, making construction more economical.[11][12] Additionally, recycled aggregates from construction waste contribute to sustainability efforts by reducing landfill use and conserving natural resources.[11]
References
↑ Neuendorf, K.K.E.; Mehl, J.P. Jr.; Jackson, J.A., eds. (2005). Glossary of Geology (5thed.). Alexandria, Virginia: American Geological Institute. p.11.
↑ T. Calligaro; Y. Coquinot; L. Pichon; B. Moignard (2011). "Advances in elemental imaging of rocks using the AGLAE external microbeam". Nuclear Instruments and Methods in Physics Research B. 269 (20): 2364–2372. Bibcode:2011NIMPB.269.2364C. doi:10.1016/j.nimb.2011.02.074.
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