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

Abstract

The cement industry contributes approximately 8% of global CO₂ emissions, driving research into supplementary cementitious materials. This paper investigates the mechanical and durability properties of concrete incorporating rice husk ash (RHA) as a partial replacement for Ordinary Portland Cement (OPC) at replacement levels of 5%, 10%, 15%, and 20% by weight. Standard concrete mix designs (M25 grade) were prepared and tested for compressive strength at 7, 28, and 56 days, alongside water absorption, chloride ion penetration, and sulphate resistance tests. Results indicate that 10% RHA replacement yields a 28-day compressive strength of 28.4 N/mm², exceeding the control mix. Higher replacement levels (15–20%) reduce strength but improve durability against chloride penetration by up to 34%. The findings demonstrate the viability of RHA as a cost-effective, environmentally sustainable cement supplement in Nigeria.