Performance Evaluation of Rice Husk Ash as Partial Replacement of Cement in Concrete in a Marine Environment at Escravos River, Niger Delta Area, Nigeria

Abstract

Cement has proven to cause environmental problems during its production and to be a relatively high-cost material in concrete production. Environmentally friendly, alternative binders like Rice Husk Ash (RHA) have recently been brought to bear. Therefore, the objective of this paper is to evaluate the performance of RHA (under controlled temperature and burning time) as a partial (10% and 20%) replacement of cement in concrete in a marine environment at Escravos River, Niger Delta Area, Nigeria. Concrete samples prepared with the 10% and 20% RHA in the laboratory were exposed to brackish water samples from the Escravos River, at 3 days, 7 days, 28 days and 90 days and the results compared with that of PLC concrete cast. Data obtained show that the workability of fresh concrete reduced with increase in RHA and further reduced, mixing with salt water. RHA contributed positively to the setting time of the concrete as it increased the initial setting time and reduced final setting time. 10%RHA concrete performed best under all conditions, with about 10% increase in strength. Further increase led to a slight decline in strength. As the amount of RHA increased, the ability of the concrete to resist chloride penetration, increased, with lesser average penetration depth. 10%RHA concrete showed the strongest rebar-concrete bond. 10% RHA is optimum for partial replacement of cement in concrete in marine environment, as it enhances the performance of the concrete.