Optimization of physical, mechanical and thermal properties of two-part geopolymer mortar by Taguchi method

Abstract

The reuse of waste materials is vital for reducing environmental impacts and developing sustainable construction materials. Traditional concrete, the second most used material globally, contributes significantly to carbon emissions. To address this, researchers are exploring alternative binders, with geopolymer emerging as a sustainable option due to its strength, durability, and use of recycled waste materials. In this article, the physical, mechanical and thermal properties of geopolymer mortars produced using Taguchi optimization were investigated. This approach enables the exploration of how specific process factors work together to influence the outcome, requiring the fewest possible experiments. As a result, it cuts down on the overall time, expenses, and labor involved in the process. Four factors including utilization of boron waste (at 4 levels of 0, 5, 10 and 15 %), utilization of silica fume (at 4 levels of 0, 5, 10 and 15 %), sodium (Na) concentration (at 4 levels of 6, 8, 10 and 12 %) and oven curing temperature (at 4 levels of 40, 60, 80 and 100 ⁰C) were considered. The achieved outcomes underwent assessment through the analysis of variance (ANOVA) technique in order to ascertain the most favorable magnitude for each individual factor. The results obtained from Taguchi analyses provide a significant roadmap for the advancement of geopolymer concrete technology. Laboratory scale experiment using the Taguchi optimization method have revealed that oven curing temperature significantly increase the mechanical strength of the mortar, as they contribute to ensuring homogeneity in the mortar. On the other hand, the influence of amount of silica fume was more limited. The amount of boron waste also plays a crucial role in the overall strength of mortar, with an optimal waste found to enhance both the strength of mortar and reduce thermal conductivity and specific weight. Results revealed that optimal conditions decreased thermal conductivity by 75.9 %, while flexural strength increased by 12.6 % compared to the reference mix. Specific weight was reduced by 10.3 %, and compressive strength remained comparable to the reference mix. The findings demonstrate that waste materials significantly enhance strength and insulation, providing a cost-effective, environmentally friendly alternative to traditional construction materials.