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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.
Shropshire (/ˈʃrɒpʃər, -ʃɪər/; historically Salop[3] and abbreviated Shrops) is a landlocked ceremonial county in the West Midlands of England. It borders Cheshire to the north, Staffordshire to the east, Worcestershire to the south-east, Herefordshire to the south, and the Welsh counties of Wrexham and Powys to the west. The largest settlement is Telford, and Shrewsbury is the county town.
The county has an area of 3,487 square kilometres (1,346 sq mi) and a population of 498,073. Telford (155,570), in the east of the county, and Shrewsbury (76,782), in the centre, are the only large towns. Shropshire is otherwise rural and characterised by market towns such as Oswestry (15,613), Bridgnorth (12,212), and Newport (11,387). The county contains two districts, Shropshire and Telford and Wrekin, which are both unitary areas.
Shropshire is generally flat in the north and hilly in the south, where the Shropshire Hills AONB covers about a quarter of the county, including The Wrekin, Clee Hills, Stiperstones, Long Mynd, and Wenlock Edge.[4][5] Part of the Fenn's, Whixall and Bettisfield Mosses National Nature Reserve, which extends into Wales, occupies the low-lying north west of the county.[6] The River Severn, Great Britain's longest river, runs through the county in a wide, flat valley before exiting into Worcestershire south of Bridgnorth. The village of Edgmond, near Newport, is the location of the lowest recorded temperature (in terms of weather) in England and Wales.[7]
There is evidence of Neolithic and Bronze Age human occupation in Shropshire, including the Shropshire bulla pendant. The hillfort at Old Oswestry dates from the Iron Age, and the remains of the city of Viroconium Cornoviorum date from the Roman period.[8][9] During the Anglo-Saxon era the area was part of Mercia. During the High Middle Ages the county was part of the Welsh Marches, the border region between Wales and England; from 1472 to 1689 Ludlow was the seat of the Council of Wales and the Marches, which administered justice in Wales and Herefordshire, Shropshire, Worcestershire and Gloucestershire.[10] During the English Civil War Shropshire was Royalist, and Charles II fled through the county — famously hiding in an oak tree — after his final defeat at the Battle of Worcester.[11] The area around Coalbrookdale is regarded as one of the birthplaces of the Industrial Revolution and has been designated a UNESCO World Heritage Site.[12][13]
