水泥基本上是硅酸钙的，其中四面体(硅原子是 sp3杂化的，位于四面体的

Cement is basically calcium silicate, in which the tetrahedron (silicon atoms are sp3 hybridized, located in the center of the main body of the tetrahedron, and oxygen atoms are located at the four corners of the tetrahedron) is the basic building block. The realization of cement-based composite materials does not require heat or pressure. This is why concrete processing can be performed on site (such as road construction) rather than in a factory. This process involves mixing cement particles with water to allow them to react. This reaction is an exothermic reaction (that is, heat is released during the reaction) and is called a hydration reaction. Here, water enters the cement crystals to form a hydrate gel, especially calcium silicate hydrate (abbreviated as csh, with an average chemical formula of 3cao 2sio23h2o). Partly due to the different volumes of the reaction product and the raw material, shrinkage (often referred to as dry shrinkage) is accompanied by hydration. To ensure sufficient water for hydration, the reaction is usually carried out in a humidity chamber with high relative humidity (close to 100%). In the first 24 hours of the reaction, the originally flowing cement gradually became a rigid material, so it could be removed if necessary. This part of the hardening process is called solidification. However, since the fixing material did not complete hydration, the strength did not reach the expected high level. Therefore, several weeks of treatment are required after coagulation (usually a 28-day study in the laboratory). During the curing process, the material is exposed to a humid environment for a long time in order to bring the hydration reaction into a state close to completion. The American Society for Testing and Materials has standardized five types of Portland cement. They are common (type i, the most commonly used), modified (type ii), high early strength (type iii), low heat (type iv) and sulfate resistant (type v). Effective use of discontinuous fibers in concrete requires dispersion of fibers in the mixture. When the fiber diameter is very small, such as 10 meters, dispersion is particularly challenging. The dispersion of the fiber increases as the fiber length decreases. In the case where the cement mass fraction is 15%, using silica fume (a type of fine particles) as a mixture can enhance the dispersion of fibers. Silica fume is usually used with a small amount of methyl cellulose (a water-soluble polymer) to help the dispersion of fibers and the working performance of the mixture. Latex (usually a copolymer of styrene and butadiene, used in the form of a particle dispersion, usually used for 15-20% cement quality) is far less effective than silica fume in assisting fiber dispersion.

Cement is essentially calcium silicate, where the tetrahedron (the silicon atom is sp3 hybrid, located in the center of the main body of the tetrahedron, and the oxygen atom is located at the four corners of the tetrahedron) is the basic building unit. The implementation of cement-based composites does not require heat or pressure. This is why concrete processing can be done on-site (e.g. road construction) rather than in factories. This process involves mixing cement particles with water to cause them to react. This reaction is a heat-releasing reaction (i.e. the release of heat during the reaction), called a hydration reaction. Here, water enters the cement crystal steaming into a hydrate gel, especially calcium silicate hydrate (c-s-h, with an average chemical formula of 3cao 2sio23h2o). Partly due to the difference in volume of the reaction product and the raw material, contraction (often referred to as dry shrinkage) is accompanied by hydration. To ensure that there is enough water for hydration, the reaction is usually performed in a humidity chamber with high relative humidity (close to 100%). Within 24 hours of the reaction, the original flowing cement gradually became a rigid material and could be removed if needed. This part of the hardening process is called solidification. However, the strength is not as high as expected because the fixed material does not complete the hydration. Therefore, the coagulation takes several weeks of treatment (usually 28 days of research in the laboratory). During curing, the material is exposed to moisture for a long time in order to bring the hydraization reaction to a near-completed state. The American Society for Materials and Testing has standardized five Portland cements. They are common (type i, the most commonly used type), modified (ii type), high morning strong (iii type), low heat (iv type) and anti-sulfate (v type). The effective use of discontinuous fibers in concrete requires dispersing the fibers in the mixture. Dispersion is particularly challenging when the diameter of the fiber is small, such as 10 meters. The dispersion of fiber increases with the decrease of fiber length. With a cement quality score of 15%, the dispersion of fibers can be enhanced by using silicone ash (a fine particle) as a mixture. Silicone ash is usually used with a small amount of methyl cellulose( a water-soluble polymer) to help the dispersion of fibers and the working properties of the mixture. Latex (usually a copolymer of styrene and butadiene, used in the form of a granule dispersion and typically used in 15-20% cement quality) is far less effective than silicon ash in assisting fiber dispersion.

Cement is basically calcium silicate, and tetrahedron (silicon atom is SP3 hybrid, located in the main center of tetrahedron, and oxygen atom is located in four corners of tetrahedron) is the basic construction unit. There is no need for heat or pressure to realize cement-based composites. This is why concrete processing can be carried out on site (such as road construction) rather than in the factory. The process involves mixing the cement particles with water so that they react. This kind of reaction is exothermic reaction (i.e. releasing heat in the reaction process), which is called hydration reaction. Here, water enters the cement crystal to form a hydrate gel, especially calcium silicate hydrate (C-S-H for short, the average chemical formula is 3CaO 2sio23h2o). Due in part to the different volume of reaction products and raw materials, shrinkage (usually called dry shrinkage) is accompanied by hydration. In order to ensure that there is enough water for hydration, the reaction is usually carried out in a humidity chamber with high relative humidity (close to 100%). During the first 24 hours of the reaction, the original flowing cement gradually becomes a rigid material, so it can be removed if necessary. This part of the hardening process is called solidification. However, due to the incomplete hydration of the fixed material, the strength did not reach the expected high level. As a result, treatment is required weeks after coagulation (usually in a laboratory study for 28 days). In the curing process, the material is exposed to the humid environment for a long time, so as to make the hydration reaction enter the state of near completion. Five kinds of Portland cement have been standardized by American Society for testing and materials. They are common (type I, the most commonly used type), modified (type II), high early strength (type III), low heat (type I V) and sulfate resistant (type V). The effective use of discontinuous fibers in concrete requires the dispersion of fibers in the mixture. Dispersion is particularly challenging when the fiber diameter is small, such as 10 meters. The dispersion of fiber increases with the decrease of fiber length. When the cement content is 15%, silica fume (a kind of fine particle) can be used as a mixture to enhance the dispersion of fiber. Silica fume is usually used with a small amount of methylcellulose, a water-soluble polymer, to help the dispersion of the fibers and the workability of the mixture. Latex (usually a copolymer of styrene and butadiene, used in the form of particle dispersion, usually used for 15-20% cement quality) is far less effective in assisting fiber dispersion than silica fume.