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Chlorides, particularly calcium chloride, have been used to shorten the setting time of concrete. [5] However, calcium chloride and (to a lesser extent) sodium chloride have been shown to leach calcium hydroxide and cause chemical changes in Portland cement, leading to loss of strength, [6] as well as attacking the steel reinforcement present ...
Calthemite straw stalactite (right side) is bent due to direction of prevailing air movement during periods of its growth. Calthemite is a secondary deposit, derived from concrete, lime, mortar or other calcareous material outside the cave environment. [1][2] Calthemites grow on or under man-made structures and mimic the shapes and forms of ...
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 root of the word calcination refers to its most prominent use, which is to remove carbon from limestone (calcium carbonate) through combustion to yield calcium oxide (quicklime). This calcination reaction is CaCO 3 (s) → CaO (s) + CO 2 (g). Calcium oxide is a crucial ingredient in modern cement, and is also used as a chemical flux in ...
Calcium aluminates can form complex salts in combination with different types of anions.Two series of calcium aluminates are known in cement chemistry: AFm and AFt phases, being respectively mono- or tri-substituted with a given divalent anion X (e.g. SO 2− 4, CO 2− 3, or hosting a divalent impurity such as SeO 2− 4 [3]...), or with two units of a monovalent anion, e.g. OH −, Cl − ...
It causes cracks to widen and deepen, quickly and efficiently takes root, and promotes calcium oxalate. By causing calcium oxalate, there is an increase in the speed of calcium ion leaching, which lowers the overall strength of concrete. In 90 days, exposure to the fungus resulted in a mass reduction of 7.2% in the concrete.
Leaching is a naturally occurring process which scientists have adapted for a variety of applications with a variety of methods. Specific extraction methods depend on the soluble characteristics relative to the sorbent material such as concentration, distribution, nature, and size. [ 1 ] Leaching can occur naturally seen from plant substances ...
A leachate is any liquid that, in the course of passing through matter, extracts soluble or suspended solids, or any other component of the material through which it has passed. Leachate is a widely used term in the environmental sciences where it has the specific meaning of a liquid that has dissolved or entrained environmentally harmful ...