Expanded Polystyrene/Tyre Crumbs Composites as Promising Aggregates in Mortar and Concrete

A composite material comprising expanded polystyrene (EPS), granulated tyre rubber (GTR), and a compatibilizer is demonstrated as a possible replacement for fine and coarse agglomerates in mortar and concrete systems, respectively. Two different polymer blending processes (solvent/low shear blending and melt/high shear blending) are used, and the resulting composite material utilized as aggregate to replace sand and cement for mortar and concrete block development. Critical properties such as workability, compressive and flexural strengths, water absorption, bulk density, and porosity are measured before and after aggregate replacement. The novel composite material led to significant improvements, boosting compressive strength by 7.6% and flexural strength by 18% when sand was replaced and further increasing compressive strength by 22.2% and flexural strength by 5.26% with cement replacement. However, a decrease in compressive and flexural strength was observed when plain EPS and plain GTR were used separately as aggregate replacements. This work proposes a pathway for the successful reincorporation of difficult-to-recycle materials such as EPS and GTR, otherwise destined for landfill, back into the supply chain for the construction industry. Moreover, this research represents the first reported work where the overall properties of mortar have surpassed those of standard mortar when substituted with recycled EPS or GTR.