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Construction Aggregate
Construction aggregate, or simply aggregate, is a broad category of coarse- to medium-grained particulate material used in construction. Traditionally, it includes natural materials such as sand, gravel, crushed stone. As with other types of aggregates, it is a component of composite materials, particularly concrete and asphalt. Aggregates are the most mined materials in the world,[1][2] being a significant part of 6 billion tons of concrete produced per year.[3] Aggregate serves as reinforcement to add strength to the resulting material. Due to the relatively high hydraulic conductivity as compared to most soil types, aggregates are widely used in drainage applications such as foundation and French drains, septic drain fields, retaining wall drains, and roadside edge drains. Aggregates are also used as base material under building foundations, roads, and railroads (aggregate base). It has predictable, uniform properties, preventing differential settling under the road or building. Aggregates are also used as a low-cost extender that binds with more expensive cement or asphalt to form concrete. Although most kinds of aggregate require a form of binding agent, there are types of self-binding aggregate which require no form of binding agent.[4] More recently, recycled concrete and geosynthetic materials have also been used as aggregates.
The Metropolitan Borough of Walsall is a metropolitan borough in the West Midlands, England. It is named after its largest settlement, Walsall, but covers a larger area which also includes Aldridge, Bloxwich, Brownhills, Darlaston, Pelsall and Willenhall. It also serves as the post town for nearby Cannock Chase District and Lichfield District respectively.
The borough had an estimated population of 254,500 in 2007.[2]
The current boundaries were set as part of the provisions of the Local Government Act 1972, with a change to the north of the borough in 1994.[3] It is bounded on the west by the City of Wolverhampton, the south by the Metropolitan Borough of Sandwell, to the south east by the City of Birmingham, and by the Staffordshire districts of Lichfield, Cannock Chase and South Staffordshire to the east, north and northwest respectively. Most of the borough is highly industrialised and densely populated, but areas around the north and east of the borough are open space.
In 1986 the borough became an effective unitary authority when the West Midlands County Council was abolished. However it remains part of the West Midlands for ceremonial purposes, and for functions such as policing, fire and public transport.
