Where are aggregates found?
Aggregates are sourced from a variety of places. The majority of aggregates occur as natural materials; these include hard rocks that are crushed to the required particle sizes or unconsolidated deposits of sand and gravel formed by water, glacial or wind action. Unconsolidated aggregates are found mostly on land but are also extracted beneath the sea. Aggregates from these sources are called primary aggregates. The most important sources of primary aggregates in Britain are crushed rock of which the principal types are limestone, igneous rock and sandstone, and sand and gravel, both land-won and marine dredged. Secondary aggregates are formed as by-products of other mineral extraction activities or other industrial processes.
Aggregates can also be created from recycled materials, as road surfaces, runways or buildings are demolished and crushed. Of the estimated total supply of aggregates in Great Britain in 2003, very broadly 70% was obtained from natural deposits on land (sand and gravel, and crushed rock), 5% from marine sources and 25% from recycled and secondary sources.
The UK has large resources of material suitable for use as aggregate and in comparison with other mineral resources in the UK they are relatively widespread. Historically, therefore, the UK has been self-sufficient in the supply of primary aggregates (crushed rock, sand and gravel). However, the distribution of primary aggregate resources is uneven. In particular, there is an almost total absence of hard rock suitable for crushed rock aggregate in southern, eastern and parts of central England, where demand is high. Consequently, where aggregate resources occur in proximity to major centres of demand they are extensively worked.
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