Potential Use of Coal Bottom Ash as Partial Replacement of Cement in Concrete

This project investigates the potential use of Coal Bottom Ash (CBA) as partial replacement of cement in concrete. The CBA used in this research work was obtained from Obajana cement plant in Kogi state of Nigeria, which was grinded and passed through 75µmm BS sieve. The result of the chemical composition of CBA shows that, the CBA falls within the limit of class C pozzolana. The result of AIV of coarse aggregate was found to be 18.9%, and that of ACV was found to be 18.6%. The specific gravity of both fine and coarse aggregate was found to be 2.65 respectively. The consistency of the cement-CBA paste increase with an increase of the CBA content. The compressive strength test at 28days curing for 0%, 5%, and 10% CBA replacement levels attain the target compressive strength (25N/mm2), while that of 15%, 20%, and 25% CBA replacement levels didn’t attain. The strength value at 5% CBA replacement level increased over that of the control before decreasing at the other higher replacement levels. The study however, shows that 5% replacement levels produce the optimum strength, and the strength of concrete increases with ages of curing. The SEM analysis test indicates that CBA act as filler and occupy the voids between the aggregates, thereby making the concrete more compact and having higher densities.