Investigation of rice husk ash cementitious constituent in concrete

This research evaluates rice husk ash (RHA) as a cementitous constituent in concrete productions. Raw rice husk obtained from rice mill situated in Ilorin metropolis, Kwara State, Nigeria was burnt in a furnace at a controlled temperature of 700^oC for a period of four hours. The ash was analysed for its physical and chemical properties. The mechanical performance of the ash in the concrete was investigated when used as a partial replacement for cement in concrete at 10%, 20% and 30% respectively with a control test that contains 0% RHA. Experimental findings showed that the RHA can be categorized as N-class pozzolana according to ASTM C618-12. The workability of the concrete falls as the RHA content increases. It was also observed that the compressive strength of Rice Husk Ash Concrete (RHAC) increases with curing age but decreases as the percentage of cement replacement with ash increases. The density of the concrete produced also reduces even with age as the percentage replacement of cement with ash increases. The optimum compressive strengths of RHAC are 25.80 N/mm², 22.73 N/mm² and 19.6N/mm² while the corresponding densities are 2449.67Kg/m³, 2348.33Kg/m³ and 2265.67Kg/m³ respectively at 10%, 20% and 30% at 28 days curing age when compared with the control test which is 27.47 N/mm² and 2517.67 Kg/m³. These values for RHAC produced can therefore be used for reinforced concrete with either normal or lightweight aggregates. This will not only improve the quality of the concrete but also reduce drastically burning of agricultural waste that causes environmental pollution.