Ecofriendly concrete production with binary blends of rice husk ash and micro-silica: mechanical strength, durability, and ECM

Concrete consumption has new obstacles as it moves towards a more sustainable strategy, including the development and implementation of cleaner technology. Production of concrete correlates with excessive use of natural resources as well as environmental degradation, which can be mitigated in part by replacing cement with industrial waste. Rice husk ash (RHA) is a widespread-sustainable agricultural by-product from rice milling in rice-producing countries whereas Micro Silica (MS) is a by-product of the manufacturing process of elemental silicon/silicon alloys in electric arc furnaces and both have gained the attention of researchers as a potential supplemental cementitious material in concrete production. In this study, nine mixes were prepared and tested to investigate the simultaneous application of RHA with 7.5%, 10% and 15% and SF with 7.5% 10% and 15% proportions respectively as cement replacement on concrete properties. Compressive strength, tensile strength, flexural strength and slump tests were used to determine the characteristics of both fresh and hardened concrete. Measurements were also taken of the concrete specimens’ chloride resistivity, and short-term water absorption. In addition, all mixtures underwent cost and environmental evaluations, and the optimal mixes were identified based on their overall performance. The results showed that the mix made with 10% RHA and 10% MS (R10-M10) have higher mechanical strength, lower water absorption, and lower porosity percentage. Concrete mix R10-M10 also producing less chloride ingress and also achieved the maximum combined score in environmental-cost-mechanical (ECM) score analysis.