Ordinary Portland cement composites modified with recycled liquid expanded polystyrene: Mechanical, thermal and water resistance properties

Abstract

This study explores the incorporation of Liquid Expanded Polystyrene (L-EPS) into ordinary Portland cement (OPC) composites as a sustainable route to enhance thermal and durability performance. L-EPS was synthesized using an acetone–toluene solvent system and introduced at 10–20 wt% replacement. The modified composites exhibited marked functional improvements: thermal conductivity (K) decreased by 20–30 % compared with control specimens, while the water permeability coefficient (k) was reduced by up to 87 %. Importantly, compressive strength after 28 days remained above 25 MPa, confirming their suitability for non-load-bearing structural applications. These enhancements are attributed to the void-filling and film-forming effects of L-EPS within the cement matrix. However, the incorporation of L-EPS also led to a consistent reduction in compressive and flexural strengths relative to the control mix, indicating a trade-off between functional gains and structural capacity. The findings demonstrate that L-EPS–modified OPC composites combine adequate strength with improved insulation and water resistance, making them promising candidates for partition walls, ceiling boards, renders, and façade elements, particularly in hot–humid climates where energy efficiency and moisture protection are critical.