Investigation of bond strength and flexural behaviour of geopolymer aggregate concrete beams

ABSTRACT The present study examines the bond strength and flexural behavior of geopolymer aggregate reinforced concrete beams, aiming to evaluate their potential as sustainable alternatives to traditional concrete. Geopolymer aggregates, produced from industrial by-products such as slag, offer an eco-friendly solution with a reduced carbon footprint. The experimental program includes a comprehensive series of tests on concrete beams reinforced with geopolymer aggregates, assessing their mechanical properties, bond strength between aggregates and reinforcing steel, and their flexural performance under loading conditions. For 10 mm reinforcements, geopolymer aggregate concrete has a bond strength increase of 3.2% and 4.4% compared to normal concrete, while for 12 mm bars, the increase is 2.4%. Ultimate load-carrying capacity in normal concrete is 15.6% higher than geopolymer aggregate concrete. Geopolymer aggregate concrete shows increased deflection at initial loading due to a lower modulus of elasticity, affecting crack control, but this is recommended for higher grades of concrete. Results indicate that geopolymer aggregate reinforced concrete exhibits comparable, if not superior, bond strength to conventional concrete. It is found that bond stress is increased up to 12% for geopolymer aggregate concrete than normal concrete. Additionally, flexural behavior analysis reveals enhanced performance characteristics, such as increased load-carrying capacity and ductility. These findings underscore viability of geopolymer aggregates in structural applications, promoting adoption of green materials in construction while maintaining structural integrity and performance.