Analysis of Chemical Compositions of Portland Cement and Limestone from Four Geopolitical Zones of Nigeria

Abstract

Cement, a major binding material in concrete making, influences the quality of concrete so produced with it; as such its chemistry dictates the chemistry of the concrete. Poor quality cement has recently been implicated as the main causes of incessant building collapses in Nigeria. The physicochemical analysis of limestone used in the production of various brands of Portland cement in four geopolitical zones of Nigeria (north east NE, north west NW, north central NC, and south west SW) was investigated using standard methods. Each of the limestone and cement samples was randomly collected from their respective sample points at the four different geopolitical zones of Nigeria. Each of the collected samples was ground and sieved to 2 mm mesh size. The limestone was rich in lime content that ranged from 45.91% ± 0.30% to 49.0% ± 0.19%. Among the cement samples, percent SiO 2 ranged from 19.95 ± 0.25 (NW) to 20.18 ± 1.02 (NC), Al 2 O 3 4.98 ± 0.18 (NW) to 5.82 ± 0.38 (NE), Fe 2 O 3 2.76 ± 1.00 (NE) to 3.82 ± 0.21 (SW), CaO 60.18 ± 0.27 (NE) to 65.10 ± 0.98 (NC), MgO 1.93 ± 0.04 (NC) to 2.50 ± 0.10 (NE), SO 3 0.93 ± 0.50 (NE) to 2.02 ± 0.13 (NW). The results showed that virtually all the cement samples analyzed conformed well to the BSEN 196-2 standard. However, the loss on ignition (LOI) deviated considerably (7.82% to 8.72%) from 4% maximum by the standard. Also, the lime saturation factor (99.70%) obtained for north central cement was slightly higher than the specified range of 92.0 to 98.0%. It could be deduced from this study that the various cements available in Nigerian market from the four geopolitical zones are of good quality. Nevertheless, other processes that lead to the production of a good concrete such as the mix ratio of cement, gravel, sand and water, use and quality of iron rods, and other building materials need to be professionally checked for quality assurance. The findings from this study can be a useful guide to the chemist, environmentalist, construction industry, and the general public on the quality of cements available in Nigerian market.