Strength and Durability Assessment of Concrete with Ethiopian Rice Husk Ash as Partial Replacement of Cement

Abstract

This study investigates the effectiveness of rice husk ash (RHA) as a partial or full replacement of cement in manufacturing of concrete. C20 grade concrete was chosen for this study and different mixes of concrete with replacement of ordinary portland cement with rice husk ash at different substitution levels (10%, 20%, 30% and 40%) were tried. The performance of the new composite was adjudged by carrying out fresh (workability), mechanical (compressive strength and split tensile strength) and durability (water absorption, water desorption and sorptivity) tests. The experimental results at fresh state of concrete revealed that, due to the higher surface area of RHA, workability of concrete slightly decreases compared to controlled concrete. At hardened state of concrete, the mechanical property test results revealed that the new composite with 10% of RHA as a partial replacement of cement has a better strength compared to the controlled concrete which is related to the pozzolanic nature of the rice husk ash. From durability perspective, the new composite showed a better resistance to water absorption, desorption and sorptivity with inclusion of rice husk ash upto 20% as partial replacement of cement. Hence, it can be concluded that rice husk ash can be used as a partial replacement of ordinary portland cement in manufacturing of concrete. The utilization of rice husk ash by the construction industry in Ethiopia will not only help in safe disposal of the waste but also will be a sustainable approach for construction in Ethiopia.