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Alteration of hardened cement paste composition, with monosulfate aluminates phase converting to ettringite and, in later stages, gypsum formation. The necessary additional calcium is provided by the calcium hydroxide and calcium silicate hydrate in the cement paste; The effect of these changes is an overall loss of concrete strength.
Degraded concrete and rusted, exposed reinforcement bar (rebar) on Welland River bridge of the Queen Elizabeth Way in Niagara Falls, Ontario. Concrete degradation may have many different causes. Concrete is mostly damaged by the corrosion of reinforcement bars due to the carbonatation of hardened cement paste or chloride attack under wet ...
CPP and CPR methods, developed over the last 40 years, are used in lieu of asphalt overlays and bituminous patches to repair roads when longer lasting solutions are desired. When installing pavers over top of an existing asphalt of concrete pad, there are three installation options: sand set, bituminous set, and mortar set. [1]
The alkali–silica reaction (ASR), also commonly known as concrete cancer, [3] is a deleterious internal swelling reaction that occurs over time in concrete between the highly alkaline cement paste and the reactive amorphous (i.e., non-crystalline) silica found in many common aggregates, given sufficient moisture.
The ancient Romans used a type of lime mortar that has been found to be self-healing. [8] The stratlingite crystals form along the interfacial zones of Roman concrete, binding the aggregate and mortar together and this process continued even after 2000 years and it was discovered by the geologist Marie Jackson and her colleagues in 2014.
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]
A pervious concrete street in 2005. Pervious concrete (also called porous concrete, permeable concrete, no fines concrete and porous pavement) is a special type of concrete with a high porosity used for concrete flatwork applications that allows water from precipitation and other sources to pass directly through, thereby reducing the runoff from a site and allowing groundwater recharge.
Portland cement blends are often available as inter-ground mixtures from cement producers, but similar formulations are often also mixed from the ground components at the concrete mixing plant. Portland blast-furnace slag cement , or blast furnace cement (ASTM C595 and EN 197-1 nomenclature respectively), contains up to 95% ground granulated ...