This kind of cement known as Alumina Cement Fondu is manufactured in entirely different way from that of Portland Cements. The raw materials used for its manufacture are chalk and bauxite which is a special clay of extremely high alumina content. The manufacture of this type of cement is more expensive than the Portland cement, though it has many advantages over other types of cement. High Alumina cement is characterized by its dark colour, high early strength, high heat of hydration and resistance to chemical attack. It thus produces concrete of far greater strength and in considerable less time than Rapid Hardening Portland Cement, allowing earlier removal of the form work. However, grate care should be taken in the use of high alumina cement, and it must not be mixed with any other type of cement, since the heat given off on setting is grater than the other cements.
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