ABSTRACT
The crucial components of Portland cement are calcium silicates, which in the manufacturing process are formed by heating a mixture of calcium oxide (CaO) and silicon dioxide (or silica, SiO2) to high temperatures. The manufacturing process is relatively simple in principle, although the high temperatures and large quantities involved require sophisticated monitoring and control systems to ensure that a uniform high quality product is obtained. Portland cements are fine grey powders. Portland cement consists of a mixture of compounds formed from a number of oxides at the high temperatures in the burning zone of the kiln. This chapter gives the approximate range of oxide proportions that can be expected in Portland cements. For an initial period after mixing, the fluidity or consistency of a paste of cement and water appears to remain relatively constant. The chapter shows the timescales and the contributions of the reactions of the individual compounds to the development of the cement strength.
