Evaluation of the mechanical characteristics of bagasse ash concrete using response surface methodology

Assessing the mechanical properties of Sugarcane Bagasse Ash (SCBA) concrete is essential for improving its strength and durability while ensuring its viability as a sustainable building material. This study focuses on optimizing SCBA concrete by partially replacing Ordinary Portland Cement (OPC), thereby minimizing carbon emissions and maximizing resource efficiency in construction. Using Response Surface Methodology (RSM) with a Central Composite Design (CCD), the effects of varying mix proportions on compressive and flexural strength were evaluated. Experimental findings demonstrate that SCBA significantly improves concrete performance at an optimal dosage, with 2.22% SCBA, 13.33% OPC, 37.78% fine aggregates, and 46.67% coarse aggregates yielding the highest compressive strength of 29.34 MPa. Similarly, a mix of 2.04% SCBA, 20.41% OPC, 34.69% fine aggregates, and 42.86% coarse aggregates produced the maximum flexural strength of 7.98 MPa. However, an excessive SCBA content decreased compressive strength to 18.75 MPa and flexural strength to 3.15 MPa, highlighting the negative impact of higher ash content. The developed quadratic model, validated through analysis of variance (ANOVA), achieved high predictive accuracy (R2 = 0.9202 for compressive strength and R2 = 0.9212 for flexural strength), confirming its reliability. The optimized response surface factor levels ratio of 0.25:0.039:0.425:0.525 for cement, SCBA, fine and coarse aggregates respectively was generated using desirability function, which led to maximized compressive strength of 28.582 MPa and flexural strength of 7.912 MPa. Additionally, a Student’s t-test (p-value = 1.0) verified no statistically significant difference between experimental and predicted values, ensuring model dependability. These findings offer a practical framework for optimizing SCBA-blended concrete, balancing strength and sustainability, and supporting its wider application in eco-friendly construction.