Recycling of waste expanded polystyrene concrete in lightweight sandwich panels and structural applications

Abstract

The recycling of waste expanded polystyrene (EPS) concrete in the lightweight construction sector is not yet explored. The complexity of recycling resides from concrete crushing that creates two distinct, yet inseparable phases including the hardened mortar fraction and recycled EPS beads. This study investigates the feasibility of using the waste EPS-based concrete in two different lightweight applications; i.e., sandwich panels and structural concrete complying with ACI 213 requirements. Test results showed that the lightweight concrete density and mechanical properties remain unaltered when the virgin EPS beads are replaced by recycled ones at relatively low rates not exceeding 2 kg/m3. The strength degradation becomes evident at higher rates, given the inseparable mortar fraction that weakens the aggregate skeleton due to higher porosity and water absorption. The bond to embedded reinforcement and shear strength of beams without stirrups decreased by about 20% when 3 kg/m3 of virgin EPS are replaced by recycled ones. The incorporation of 0.5% steel fibers, by volume, was efficient to mitigate the detrimental effect of such wastes and restore the lightweight concrete structural properties.