Sustainable concrete development using groundnut shell ash: A response surface methodology approach

Abstract

Climate change and global warming are primarily driven by carbon dioxide (CO₂) emissions from fossil fuel combustion across energy, transportation, and industrial sectors. Among industrial contributors, the production of ordinary Portland cement (OPC) is a significant source of emissions due to its energy-intensive processes and chemical decomposition of limestone. Cement is widely used in concrete because of its cost-effectiveness and reliability; however, its high energy consumption and environmental impact necessitate the search for sustainable alternatives. Previous studies have explored various supplementary cementitious materials (SCMs), such as fly ash, silica fume, and groundnut shell ash (GSA), but many lack optimization in their application, particularly in tailoring the GSA content with watercement (w/c) ratios to achieve optimal workability and mechanical performance. Additionally, existing research often overlooks systematic experimental designs that comprehensively evaluate fresh and hardened properties via advanced statistical techniques. This study addresses these gaps by employing response surface methodology (RSM) to optimize concrete mixtures incorporating GSA as a partial cement replacement (3–12 %) with w/c ratios ranging from 0.4–0.6. Workability (slump, Vee–Bee consistency, compaction factor) and mechanical properties (compressive strength, flexural strength, and split tensile strength) were evaluated according to Indian standards. The results demonstrated that the GSA significantly influenced the concrete properties, with an optimal mixture of 6.27 % GSA and a 0.42 w/c ratio achieving a desirability of 66.38 %. This study provides a data-driven approach to enhancing concrete sustainability by utilizing agricultural waste while addressing key shortcomings in prior research. The optimized concrete mixture not only demonstrated enhanced mechanical and fresh properties but also significantly contributes to the broader agenda of sustainable construction. By incorporating groundnut shell ash (GSA), an agricultural waste, this study promotes circular economy practices and reduces reliance on traditional cement, which is a major contributor to global CO₂ emissions. The findings underscore the feasibility of replacing a portion of OPC with GSA without compromising performance, thereby supporting the transition to greener infrastructure materials. This research lays the groundwork for scalable, eco-efficient concrete production, especially in regions with abundant agricultural residues.