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Last edited 09 Oct 2018
Sand is a type of naturally-occurring material that is of a granular, loose, fragmented composition, consisting of particulate matter such as rock, coral, shells, and so on. Sand is typically finer than gravel but coarser than silt.
The precise composition of sand varies depending on its source and the conditions prevalent at that location. In in-land continental regions, the predominant constituent of sand is silica (silicon dioxide), typically in the form of quartz. Sand that has been created over millions of years by such things as coral and shellfish is typically aragonite, which is a form of calcium carbonate.
 Uses of sand
Sand is in very commonly use in construction, often providing bulk, strength and stability to other materials such as asphalt, concrete, mortar, render, cement, and screed. Sand is also used as a base layer known as ‘blinding’, that is laid above a layer of hardcore to provide a clean, level and dry surface for construction works. It can also be used in its raw form as a decorative material in landscaping.
Sand is used in liquid form to manufacture glass, and is also used for moulding metal casting. It can be used as an abrasive in the process of sandblasting which cleans structural elements, steelwork, and so on. Sandpaper is also made using sand.
 Types of sand
The different classifications of sand are:
- Particle size: 0.6-2 mm (coarse sands), 0.2-0.6 mm. (medium sands), 0.06-0.2 mm (fine sands).
- Particle shape: Angular, subangular, rounded, flat, elongated.
- Texture: Rough, smooth, or polished.
- Composite soil types: Classified as ‘sandy gravel’ or ‘gravelly sand’. Clayey composites are described as plastic or cohesive. Silty composites are described as non-plastic or of low plasticity.
- Structure: Homogenous, inter-stratified, heterogeneous, or weathered.
Sand can be tested when batching concrete by volume in what is known as a bulking test. A silt test can be used to measure the cleanliness of a sand sample by establishing the percentage of silt present. This is important as too much silt will weaken concrete. For more information, see Testing sand.
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