Optimization of Strength Characteristics of Incinerator Bottom Ash-Based Geopolymer Concrete Using Response Surface Methodology

Abstract

Growing populations and industrial expansion have led to increased municipal waste generation and environmental concerns, as well as substantial greenhouse gas emissions from the cement industry. In response, Geopolymer concrete (GPC) has emerged as a promising, more sustainable alternative to Ordinary Portland Cement (OPC). This study employs Response Surface Methodology (RSM) to optimize four critical parameters affecting the compressive strength of Incinerator Bottom Ash (IBA): curing temperature, curing duration, activator ratio, and activator molarity. The research objectives include analyzing the oxide composition of IBA, assessing the specific gravities of materials, and developing a predictive model with three-dimensional surface plots, with Analysis of Variance (ANOVA) employed for data analysis. Results demonstrate the alumino-silicate content of IBA at 76.88%, confirming its viability as a pozzolanic material. The achieved optimal compressive strength was 21.30 N/mm² at an activator ratio of 60%, a curing temperature of 100°C, an 18 M KOH molarity, and a curing duration of 6 hours. ANOVA results indicate that all parameters significantly influence strength development (p < 0.0001), exhibiting a strong model fit with a high coefficient of determination (R² = 0.9945). Furthermore, a desirability function value of 0.99 indicates effective optimization, while a low prediction error of 1.74% confirms the accuracy and reliability of the developed model. This research emphasizes RSM's effectiveness in process optimization and supports advancements in eco-efficient geopolymer technologies, promoting the transition towards sustainable construction materials.