High alumina cement is an inorganic material that reacts with water to form a dense texture, and has excellent fire resistance, rapid hardening and chemical resistance. This type of cement is produced by grinding clinker formed from the calcination of bauxite and lime. Bauxite is an aluminum ore. It is specified that the total alumina content should not be less than 32% and the weight ratio of alumina to lime should be between 0.85 and 1.30. High alumina cement was first developed in the UK in 1925 by a cement producer called Lafarge. Since it was found to be resistant to chemical attack, it was mainly used in marine construction. When the properties of this cement, such as rapid strength increase and ease of manufacture, were discovered and widely used in precast concrete, its popularity rose. The label of high alumina cement is expressed by the 3-day compressive strength measured by the strength test method specified in the standard, and is divided into four labels: 425, 525, 625 and 725.
High alumina cement refers to a fast-hardening, high-strength, heat-resistant and corrosion-resistant cementitious material. Its main characteristics are high early strength, high temperature and corrosion resistance. High alumina cement is mainly used for projects with urgent construction period, such as pressure prevention, road and special emergency repair projects, etc., and can also be used for winter construction projects. Clinker with calcium aluminate as the main material and alumina content of about 50%, the ground hydraulic cementitious material is called high alumina cement.
The manufacturing process of high alumina cement is different from that of ordinary Portland cement. With bauxite and lime as raw materials. Mix the ingredients in the required proportions and grind into small pieces of 100mm. These lumps are fed into a kiln and heated to their melting point, which is 1600°C. The molten material falls on the steel plate and is sent to the rotary kiln for cooling. These clinkers are then finely ground in a tube mill to a fineness of not less than 2250 cm2/g.
The advantages of high-alumina cement are as follows: due to the longer setting time, the more time for mixing and placement; the chemical resistance of high-alumina cement is good; high-alumina cement can withstand high temperatures; high-alumina cement produces more heat during setting , so the frost effect is low; high alumina cement is very active and has very high compressive strength; high alumina cement also has high fire resistance.
Uses of High Alumina Cement: High alumina cement is widely used in marine construction and sewer infrastructure due to its rapid hardening and strength properties. High alumina cement is also used in refractory concrete, where higher strength is required at high temperatures.