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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.
Example of flat piece of concrete having dislodged with corroded rebar underneath, Welland River bridge across Queen Elizabeth Way in Niagara Falls, Ontario. The expansion of the corrosion products (iron oxides) of carbon steel reinforcement structures may induce internal mechanical stress (tensile stress) that cause the formation of cracks and disrupt the concrete structure.
The term “RAAC” or “Reinforced Autoclave Aerated Concrete” might also be found in original design and drawing plans for buildings constructed between 1950 and 1990. Show comments Advertisement
Research from major concrete authorities, including the American Concrete Institute, Portland Cement Association, and the National Ready Mixed Concrete Association confirm that most concrete damage is attributable to surface moisture intrusion. [citation needed] The most pervasive form of concrete damage is surface scaling from freeze/thaw.
Frost damage of early-age concrete is particularly harmful for the concrete mechanical resistance because the ice volume expansion causes micro-cracks in the concrete structures, and as a consequence it lowers the compressive strength of concrete. [4]
A finished tilt-up building. Tilt-up, tilt-slab or tilt-wall is a type of building and a construction technique using concrete.Though it is a cost-effective technique with a shorter completion time, [1] poor performance in earthquakes has mandated significant seismic retrofit requirements in older buildings.
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 ]
Based on studies in New Zealand, relating to 2011 Christchurch earthquakes, precast concrete designed and installed in accordance with modern codes performed well. [2] According to the Earthquake Engineering Research Institute , precast panel buildings had good durability during the earthquake in Armenia, compared to precast frame-panels.