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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 ...
Degrading concrete has been the focus of many studies and the most obvious sign is calcium-rich leachate seeping from a concrete structure. [5] [6] [7]Calthemite stalactites can form on concrete structures and "artificial caves" lined with concrete (e.g. mines and tunnels) significantly faster than those in limestone, marble or dolomite caves.
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.
In chemistry, efflorescence (which roughly means "the flowering" in French) is the migration of a salt to the surface of a porous material, where it forms a coating. The essential process involves the dissolving of an internally held salt in water or occasionally, in another solvent. The water, with the salt now held in solution, migrates to ...
Stone sealer. Stone sealing is the application of a surface treatment to products constructed of natural stone to retard staining and corrosion. [ 1 ] All bulk natural stone is riddled with interconnected capillary channels that permit penetration by liquids and gases. This is true for igneous rock types such as granite and basalt, metamorphic ...
Leaching is the process of a solute becoming detached or extracted from its carrier substance by way of a solvent. [ 1 ] 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 ...
Concrete debris from the March hydrogen explosion of the reactor building has been detected in the spent fuel pool. In June TEPCO discovered that the water in the pool was strongly alkaline: the pH had reached a value of 11.2. Leaching of calcium hydroxide (portlandite) or calcium silicate hydrate (CSH) from the concrete could
Sulfate attack in concrete and mortar. Cement hydration and strength development mainly depend on two silicate phases: tricalcium silicate (C 3 S) (alite), and dicalcium silicate (C 2 S) (belite). [ 1 ] Upon hydration, the main reaction products are calcium silicate hydrates (C-S-H) and calcium hydroxide Ca (OH) 2, written as CH in the cement ...