The main application of calcium aluminate cements (CAC) is as a binder in monolithic refractories. Other applications include industrial flooring products (such as cast house floors), chemical resistant mortars and concretes, sewer applications, expansive grouts, floor screeds, tile adhesives, protective coatings and in building chemistry products (where OPC is combined with CACs, to give desired setting times).
Monolithic Refractory Binder
One of the major applications of CACs is as a binder in monolithic refractories, in particular refractory castables. Typically a cement with a higher alumina content is used. The cement bonds precision graded aggregates together in the green state. Following the subsequent heat up of these materials the cement sinters with the aggregate forming a refractory matrix. Many different refractory aggregates are used in castables such as tabular alumina, bauxite, chamotte and silicon carbide. They are selected on the properties required by application. These products have applications in the iron and steel industry, in non-ferrous metallurgical industries, in the pre-heaters of cement kiln and in incinerators.
The CAC used in this application is selected on its alumina content, the higher the alumina content the higher the temperature of application the cement may be used in (pyrometric cone equivalent).
Building Chemistry Products
Building chemistry products include products such as tile adhesives, tile grouts, rapid floor screeds, and floor levelling compounds, sealers, bedding mortars and repair mortars. This diverse range of products are all composed of a mineral base which is a mixture of calcium aluminate cement and Portland cement. The mixture may then have the following added to it: gypsum, lime, fine calcareous material, slag, admixtures and polymers.
Due to the fact that liquid waste these days is becoming more and more concentrated, more resistant construction materials are required. Calcium aluminate cements contain no free lime, which is prone to attack by sulphates. In addition to this CACs provide a greater resistance to abrasion and biogenic corrosion.
Chemical Resistant Concretes
Calcium aluminate cement producing concretes with a lower porosity matrix and a greater resistance to both sulphate attack and abrasion is favoured in the formulation of chemical resistant concretes. These types of products mainly include industrial floorings such as cast house floors.
The rapid strength development and the high final strength of calcium aluminate cements make them a good choice for mining applications. Also the excellent abrasion and impact resistance makes calcium aluminate cement very suitable for this application. A composition of calcium aluminate cement, ALAG and corundum tends to be used in a shotcrete (a specialised concrete formulation which can be easily pumped to site of application then sprayed out through a nozzle) form.
Refractory concretes are manufactured and assembled into a metal enclosure. This is then finished with conventional wood, masonry materials and facades, which give them the appearance of traditional masonry fireplaces. This type of refractory concrete is produced from lightweight aggregate and high alumina cement.