Enhancing concrete strength and durability through incorporation of rice husk ash and high recycled aggregate

The global environment faces significant challenges due to the massive use of concrete, a dominant material in construction. Addressing this challenge, the present study explores the potential of recycled concrete aggregate (RCA) combined with rice husk ash (RHA) to enhance the durability and strength of recycled aggregate concrete (RAC), particularly in mixes with high RCA content. The research examines RHA as a partial substitute for Ordinary Portland Cement at 5 %,10 %,15 % and 20 % replacement levels, alongside RCA substitution rates of 80 %, 90 %, and 100 %. Five RAC mixes were evaluated: Mix-1 served as the control group with varying RCA percentages (80 %, 90 %, and 100 %) without RHA, whereas Mix-2, Mix-3, Mix-4 and Mix-5 incorporated 5 %,10 %,15 % and 20 %RHA as a cement substitute. The study evaluated parameters such as workability, compressive strength, tensile strength, water absorption, and acid resistance, in addition to employing non-destructive testing techniques like ultrasonic pulse velocity and rebound hammer tests. After 28 days of curing, Mix-4 (comprising 15 % RHA and 80 % RCA) exhibited the highest compressive strength among the tested RAC mixes, achieving a value of approximately 27 MPa. However, economic analysis revealed that Mix-5 (20 % RHA and 100 % RCA) offers a 31 % reduction in production costs, making it a viable choice for concrete manufacturing. This integration of RCA and RHA presents a sustainable, eco-friendly, and cost-effective approach to enhancing concrete strength and durability.