Manufacture of Ordinary Portland Cement
Cement is a hydraulic binder and is defined as a finely ground inorganic material which, when mixed with water , forms a paste which sets and hardens by means of hydration reactions and processes which , after hardening retains it’s strength and stability even under water.
Ordinary Portland Cement (OPC) is one of several types of cement being manufactured throughout the world, listed in table 4 are some of the more commonly used. OPC is the general purpose cement used in concrete constructions. OPC is a compound of lime (CaO) , silica (SiO2) , alumina (AL2O3) , iron (Fe2O3) and sulphur trioxide (SO3) (table 5). Magnesium (MgO) is present in small quantities as an impurity associated with limestone. SO3 is added at the grinding stage to retard the setting time of the finished cement. When cement raw materials containing the proper proportions of the essential oxides are ground to a suitable fineness and then burnt to incipient fusion in a kiln , chemical combination takes place , largely in the solid state resulting in a product aptly named clinker. This clinker , when ground to a suitable fineness , together with a small quantity of gypsum (SO3) is Portland Cement.
