111. Other inorganic binding materials

As binders are used, and other inorganic materials such as aluminous cement, magnesia and phosphate binders. These binders are needed for various construction and chemical compounds

alumina cement

In the German-speaking and used names like melted aluminous cement, aluminate cement, in English literature mostly used the name "calciumalumina (te) cement" (CAC) for the alumina cement. Commercial use of alumina cement since 1910 began in connection with the demand for sulphate binder with high early strength. Shortly thereafter, a very good temperature resistance hardened alumina cement was discovered, which led to its widespread use in the field of refractory materials. During the First World War, aluminous cement was used by the military to install gun positions, for which a rapid grasp of the alumina cement was of great importance. In the chemical-mineralogical composition and properties of aluminous cement significantly differs from Portland cement. As compared to Portland cement Al2O3 content in alumina cement above and below the CaO content.

 Production

For alumina cement with a typical content of Al2O3 - 38-40% as a raw material used mainly bauxite and limestone. The content of SiO2 should be <6%, Fe2O3 content may be up to 20%. For high alumina cement with a high content of Al2O3, which are mostly used as refractory materials to be used by specially trained high purity raw materials. Production of alumina cement is carried out mainly in coal-fired or oil bath Shaft furnaces with heating at a temperature of 1450-1600 0C. For cooling the melt is poured into a flat shape. Fine grinding is carried out in conventional cement mills, however, wear of grinding bodies and linings in this because of the great resistance to crushing is significantly higher than the Portland cement. The most important producing countries alumina cement are France, UK, Spain, USA, Japan, Croatia and China.

112. Alumina cement

Name of the material obtained from A1203 (alumina), or alumina. It is made from ground clinker, which is produced from limestone and bauxite, baked in special ovens. In some cases, instead of using iron bauxite ore bauxite ingredients iron oxide and limestone. The firing temperature may be 1200 ° C to 1500 ° C. Thus the components are brought to the sintering or melting. If the firing was carried out in special electric or blast furnace, then, at times, there is no need to grind components. Since there are all necessary conditions for the removal of silica and cement zheleza.Imeet the same grade, except that they are defined by 3-day-old, as this material hardens much faster. Just one day is enough to dial a decent strength. While conventional cement hardens within 28 days. Aluminous cement Hz and 40 other brands (50 and 60) provides a greater water resistance and density. He also characterized otlichnoymorozotoykostyu.

There are two types of materials: normal and high alumina cement. They differ from each other by the number of impurities. Thus, the first containing 3% silica and 66% alumina. A high-alumina 1% silica and 76% alumina. Use this material for urgent emergency operations, especially in the winter, as this cement provides excellent water resistance and moisture resistance. Scope - a manufacturer of all kinds of heat-resistant and expanding cement. In the process of hardening the material at high temperatures only strength is enhanced. For expanding cements used, because the material in the process increases in volume and thereby offset shrinkage. That is, he himself seals. In addition, when using the material in reinforced concrete structures, concrete is compressed and tension reinforcement, which positively affects the quality of products.