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Crushing concrete from an airfield. Concrete recycling is the use of rubble from demolished concrete structures. Recycling is cheaper and more ecological than trucking rubble to a landfill. [1] Crushed rubble can be used for road gravel, revetments, retaining walls, landscaping gravel, or raw material for new concrete.
Environmental impact of concrete. The environmental impact of concrete, its manufacture, and its applications, are complex, driven in part by direct impacts of construction and infrastructure, as well as by CO 2 emissions; between 4-8% of total global CO 2 emissions come from concrete. [ 1 ] Many depend on circumstances.
Steel furnace slag sales in 2006 were for use in road bases and surfaces (51%), asphaltic concrete (12%), for fill (18%), and the balance for other uses. Recycled glass aggregate crushed to a small size is substituted for many construction and utility projects in place of pea gravel or crushed rock. Glass aggregate is not dangerous to handle.
The output obtained from a site mix concrete plant using a 8/12 mixer is 4 to 5 metric cubes per hour which is 30-60 metric cubes per hour in a ready mix concrete plant. Better handling and proper mixing practice will help reduce the consumption of cement by 10 – 12%.
One cubic metre of gravel typically weighs about 1,800 kg (4,000 lb), or one cubic yard weighs about 3,000 lb (1,400 kg). Gravel is an important commercial product, with a number of applications. Almost half of all gravel production is used as aggregate for concrete.
The appropriate thickness of a layer of track ballast depends on the size and spacing of the ties, the amount of traffic on the line, and various other factors. [1] Track ballast should never be laid down less than 150 mm (6 inches) thick, [5] and high-speed railway lines may require ballast up to 0.5 metres (20 inches) thick. [6]
Concrete has a very low coefficient of thermal expansion, and as it matures concrete shrinks. All concrete structures will crack to some extent, due to shrinkage and tension. Concrete which is subjected to long-duration forces is prone to creep. The density of concrete varies, but is around 2,400 kilograms per cubic metre (150 lb/cu ft). [1]
Permeable interlocking concrete pavements are concrete units with open, permeable spaces between the units. [ 28 ] : 2 They give an architectural appearance, and can bear both light and heavy traffic, particularly interlocking concrete pavers, excepting high-volume or high-speed roads. [ 30 ]