The Effects Of Sugar Cane Bagasse Ash As Suplementary Cementitious Material In Production Of Concrete

2.4.1 Types of cement
    There are different types of cement depending on their composition, method of manufacturing (grinding, burning, etc.) and also the relative proportion of the different compounds. One of these types and the most commonly used one is Portland cement, which in turn is divided into many types. The other common type of cement is Portland pozzolana cement which contains some amount of pozzolanic materials
2.4.1.1 Portland cement
    Portland cement is one of the most widely used cement and is the most important hydraulic cement. It can also be used for mortar & plaster production. It is used in all types of structural concrete like walls, floors, bridges, tunnels, etc. It is further used in all types of masonry works like foundations, footings, dams, retaining walls, and pavements. When Portland cement is mixed with sand and lime, it serves as mortar for laying brick and stone; and when it is mixed with coarse aggregate and fine aggregate (sand) together with enough water, to ensure a good consistency, we get concrete. The origin of the name “Portland cement" is usually attributed to Joseph Aspdin, a brick mason in England who in 1824 took out a patent for making a powder made from mixed and ground hard limestone and finely divided clay. This forms into slurry and then is calcined in a furnace till the CO2 was expelled. He called the resulting material Portland cement because when the mortar made with it hardened it produced a material resembling the stone which was quarried near Portland, England [8]. The method of making cement has been improved upon since that time but the basic process has remained the same. Modern Portland cement is made from materials which must contain the proper proportions of lime (CaO), silica (SiO2), alumina (Al2O3), iron (Fe203) with minor amounts of magnesia and sulfur trioxide. A typical composition of general purpose Ordinary Portland cement is shown in the Table 2.1 below:

of these compounds, C3S and C3A are mainly responsible for early strength of concrete. High percentages of C3S (low C2S) results in high early strength but also high heat generation as the concrete sets. The reverse combination, that is, low C3S and high C2S develops strength more slowly and generates less heat. C3A causes undesirable heat and rapid reacting properties, which can be prevented by adding CaSO4 to the final product.