Cement
The word cement refers to any type of adhesive that is able to bond and integrate minerals. Cement is a soft, water-absorbing, sand and gravel (aggregate) binder, which is essentially composed of fused and molten compounds of calcium oxides, silicon, aluminum and iron. The mortar of this powder is able to set and harden over time in the presence of air and water. The constituents slowly hydrate and the mineral hydrates solidify and harden. The interlocking of the hydrates gives cement its strength. Contrary to popular belief, hydraulic cement does not set by drying out — proper curing requires maintaining the appropriate moisture content necessary for the hydration reactions during the setting and the hardening processes. within 28 days under necessary hydration, it has a minimum resistance of 250 kg / cm2.
Cement is generally a material that has the ability to solidify and adhere aggregates to each other and create an integrate content. This definition is so comprehensive that it can include a variety of adhesives such as adhesives used to bond stone to stone pieces or stone to metal.
The term Cement in engineering majors are cements with calcareous roots. Accordingly, cement is a combination of calcium oxide (lime) with other oxides such as silicon oxide, aluminum oxide, iron oxide, magnesium oxide and alkaline oxides that have a high affinity with water and in the vicinity of air and even water over time. It hardens and has a privileged resistance.
Hydraulic cement hardens as a result of mixing with water. Hydraulic cements are water resistant. Portland cement, alumina cement and rubber cement are different types of hydraulic cements.
Despite the combination of gypsum with water and its hardening, because the product does not have the ability to last long in water and dissolves over time, gypsum is not considered a group of hydraulic cements. Hardened lime is resistant to water, but because it hardens due to the absorption of carbon dioxide gas and not water, it is separated from the group of hydraulic cements.
The main raw materials used to make hydraulic cements are lime, silica, alumina and iron oxide.
Portland cement is a material that is produced by mixing and grinding clinker, gypsum or anhydrite and additives according to the standard. If the amount of additives exceeds the specified amount, the result will be called mixed concrete. Minerals used in the production of Portland cement include limestone, clay and corrective materials.
Aluminum cement is also a type of cement having hydraulic properties. The cement is composed of the primary components of limestone and bauxite, and the raw mixture has high percentages of calcium oxides, aluminum, silicon, iron and small amounts of magnesium oxides.
Cement is an essential and inseparable part of concrete, and concrete, as a building material with the concept of mortar and artificial stone, is very classic. Most of the material left over from volcanoes - volcanic ash - has a cementitious property.
Global cement production is now more than one billion tons, and it will reach three billion tons. In terms of weight, cement production has the highest figure among the world's industrial material. On average, 7 type of material such as limestone, clay, gypsum, iron ore, marl, and silica is required to produce each ton of cement,