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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 conditions. Chemical damage is caused by the formation of expansive products produced by chemical reactions (from carbonatation, chlorides, sulfates ...
A cement is a binder, whereas concrete is the composite material resulting from the mixing and hardening of cement with water (or an alkaline solution in the case of geopolymer cement), and stone aggregates. Materials of both types (geopolymer cements and geopolymer concretes) are commercially available in various markets internationally.
The cement is made by fusing together a mixture of a calcium-bearing material (normally calcium oxide from limestone) and an aluminium-bearing material (normally bauxite for general purposes, or refined alumina for white and refractory cements). The melting of the mixture is achieved at 1600 °C and is energy demanding.
Cementation (geology) A brief, easy-to-understand description of cementation is that minerals bond grains of sediment together by growing around them. This process is called cementation and is a part of the rock cycle. Cementation involves ions carried in groundwater chemically precipitating to form new crystalline material between sedimentary ...
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 − ...
The main components of LC3 cements are clinker, calcined clay, limestone, and gypsum. [24] [25] [26] The fresh concrete production involves synergetic hydration.[10] [27] Adding large amounts of calcined clay and ground limestone to the dry cement powder, [28] [29] when adding water to the mix for making concrete, cement and additives start to hydrate and the soluble aluminates released in ...
Alkali–silica reaction. Characteristic crack pattern associated with the alkali–silica reaction affecting a concrete step barrier on a US motorway. Note the typical fatty aspect of the silicagel exudations imbibing the concrete surface along the two sides of the cracks. [1][2] The alkali–silica reaction (ASR), also commonly known as ...
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.