Optimization and performance of expanded polystyrene concrete for sustainable infill wall construction using response surface methodology.

The increasing superimposed dead load (SDL) from conventional brick or concrete block infill walls of frame structures necessitate the development of lightweight and sustainable alternatives. During earthquakes, these heavy infill walls attract significant seismic forces due to their mass. This study investigates the use of expanded polystyrene (EPS) concrete panels as a lightweight alternative to traditional infill walls. EPS panels with densities of 1000-1100 kg/m³, using both 2.5% small size (0.71-1 mm) and 2% large size (1-1.66 mm) EPS beads, were developed and evaluated. Mix designs were optimized using statistical modeling techniques, including Analysis of Variance (ANOVA) and Response Surface Methodology (RSM), confirming high model accuracy (R² > 0.80). Experimental tests assessed various properties of EPS concrete panels and shown a 47% reduction in thermal conductivity and 60-70% lower permeability compared to bricks. Water absorption was 50% lower, and despite their 43-48% reduced density, the panels achieved 75% of the compressive strength of conventional materials. Notably, diagonal force stability was approximately 30% greater than brick masonry. These findings suggest EPS concrete panels significantly reduce the non-structural dead load with improved thermal conductivity, water absorption, diagonal shear resistance and other properties, leading to more economical, sustainable construction, thus offering a durable and heat-resistant alternative to traditional infill wall materials.