Enhancing flexural performance of rubberized concrete beams through incorporation of rice husk ash as cement replacement

The quest for sustainable concrete production emphasizes human health and environmental safety while significantly reducing CO₂ emissions associated with traditional cement manufacturing, which is vital in combating climate change. Moreover, the novel application of by-products with pozzolanic properties not only diminishes environmental waste but also enhances the performance of concrete constructions. This research studies the sustainable application of crumb rubber (CR) and rice husk ash (RHA) in reinforced concrete (RC) beams. The research proposes a sustainable approach to mitigate the decreased flexural capacity in rubberized RC beams by incorporating rice husk ash (RHA) as a substitute for cement. Nine different concrete mixtures were designed with varying substitution ratios of RHA and CR as partial replacements for cement and fine aggregate (FA), respectively. The substitution ratios considered were 0 %, 10 %, or 20 % for RHA and 0 %, 5 %, or 10 % for CR by FA. Nine simply supported RC beams were cast and tested. The findings demonstrated that substituting cement with RHA at an ideal replacement ratio of 10 % enhanced the concrete strength, whereas the use of CR had a detrimental impact. The flexural capacity, stiffness, and toughness of the examined beams improved with the inclusion of RHA up to 10 %; they then declined with the inclusion of 20 % RHA but continued to be higher than those of the control specimen. The exploration of concrete mixture substitution ratios highlights a compelling balance between performance and sustainability. According to the experimental results, the best substitution ratio for the concrete mixture is a combination of 10 % RHA and 10 % CR, which only slightly reduces the ultimate load by 3.1 %. Finally, the experimental outcomes were compared with the predicted results of ACI 318–19 approaches.