Behavior of Lightweight Concrete Incorporating Pozzolana Aggregate and Expanded Polystyrene Beads

Abstract

The inclusion of Expanded Polystyrene (EPS) beads in concrete mixtures presents a practical method for preserving natural aggregate resources and addressing the environmental impact caused by the accumulation of EPS waste. This research aims to explore the compressive strength, response to elevated temperatures, and shear performance of lightweight concrete by substituting pozzolana aggregates (PA) with EPS. Several concrete mixes were prepared by replacing different proportions of coarse and fine aggregates with EPS. The two most promising mixes were selected for further investigation. In the first mix, 12.5% of the coarse aggregate and 25% of the fine aggregate were substituted, while the second mix included 12.5% of the coarse aggregate, 25% of the fine aggregate, and 250ml of Master Glenium 51a as a superplasticizer. To establish a baseline, a control mix was prepared using pozzolana coarse aggregate without EPS. The density and compressive strength of the concrete mixtures were assessed by testing standard cubes at room temperature, 250°C, and 500°C. Additionally, three simply supported beams with a span length of 1.05m and a square cross-section measuring 150mm on each side were subjected to a four-point loading scheme to investigate the shear behavior of the concrete produced from the aforementioned mixes. The study findings revealed that the density and compressive strength of the hardened concrete decreased as the percentage of EPS replacement increased. However, the mix incorporating EPS and 250ml of Master Glenium 51a as a superplasticizer achieved a compressive strength of 40.11 MPa at 28 days, indicating the potential of EPS in the lightweight concrete industry. The concrete mixes containing EPS exhibited a lesser reduction in compressive strength at 500°C compared to the control mix without EPS. Furthermore, the beam made with the mix containing EPS and the superplasticizer demonstrated the highest shear capacity among the other beams. Based on these results, this study suggests that incorporating EPS as a partial substitute for pozzolana aggregate holds promise in the lightweight concrete industry, considering its observed density, compressive strength, resistance to high temperatures, and shear behavior.