Properties of Cement and Cementing Materials

Certain types of cements used for specific requirements are called special cements. These cements can be used at very high or very low temperatures. Some special cements can also be used in acids. Special cements such as silicate cement have a very high setting rate. Barium and strontium cements are resistant to radioactive radiations. The different types of special cements are high alumina cement, sorel cement, silicate cement, waterproof cement, high early strength cement, barsium, and strontium cement.
High alumina cement is obtained by fusing limestone and bauxite with small amounts of silicon oxide and titanium oxide at I500 C-1600 C in a rotatory kiln, and then grinding the resulting products to fineness in the same method as that used of Portland cement. The essential constituents of high alumina cement are:
Calcium Oxide (CaO): 38-40 %
Alumina(Al, 03): 45-50%
Silica (SiO): 10%
Ferric Oxide (Fe, 03): 5-10 %
The important compounds of high alumina cements are monocalcium aluminates, tricalcium pentaluminate, dicalcium silicate, and tetra calcium aluminoferrite.
Sorel cement is prepared by adding strong magnesium chloride to finely ground calcinated magnesia. This cement sets to hard mass within 3-4 hours. The rate of hardening of the cement further increases with the addition of 1.5% calcium chloride. Calcium chloride accelerates the hydration process of dicalcium silicate and tricalcium silicate, which provide strength to the cement. The advantage of sorel cement is its accelerated rate of setting, which is useful during cold weather. Sorel cement is used in...