Optimization of thermal conductivity and lightweight properties of clay bricks

Abstract

As the demand for energy increases worldwide, the construction industry, one of the most energy-intensive sectors, requires lightweight and high-thermal-performance materials. To address this, a multi-objective optimization approach was used in this study to identify the most suitable solutions for producing strength-fired clay bricks with low thermal conductivity. Porous bricks were produced with organic waste additives to illustrate the relationship between compressive strength and thermal conductivity. A 3-factor and 3-stage Box-Behnken experimental design was utilized, with a pore-forming additive ratio (0–10% by weight of pine nut shells), firing temperature (850–1050 °C), and firing time (2–6 h) as the variables. The fired bricks' physical, mechanical, and thermal properties were determined using standard analysis methods. The bricks' compressive strength and thermal conductivity functions were generated using neuro-regression systematics. Multiple targets were defined, including minimizing the thermal conductivity and maximizing the compressive strength of the bricks. The genetic algorithm was employed to identify Pareto-optimal solutions, and the final sets of low thermal conductive-strength brick production were chosen based on these solutions. Two sets were proposed to achieve the lowest thermal conductivity, and the results confirmed the validity and feasibility of the optimization study.