Thermo-physical and mechanical characteristics of sand-based lightweight composite mortars with recycled high-density polyethylene (HDPE)

Abstract

Today, a large number of research projects are concerned with the recycling of plastic waste to be reused in the field of construction. This work, which is part of a research programme, focuses on the valorization of plastic waste from high density polyethylene (HDPE) pipes, to be used as aggregates. The HDPE aggregates were used as partial replacements of natural sand at 0, 15, 30, 45 and 60%, for the same volume. Only one particle size of the HDPE aggregates was used in each composition of the lightweight composite mortars (LWCM). Prismatic specimens 4 × 4 × 16 cm3 were prepared with a ratio W/C = 0.5. The density of the composite mortars was measured in the fresh and cured states. The compressive and flexural strengths, the thermo-physical characteristics as well as the ultrasonic pulse velocity (UPV) and the dynamic modulus of elasticity (Ed) were also investigated. In addition, composite mortars were analysed using a Scanning Electronic Microscope (SEM). Laboratory tests revealed encouraging results. Compared to the normal composite mortar (NMC), outcomes showed that composite mortar with 60% HDPE aggregates (LWCM60) increased ductility and reduced by 73% the dynamic modulus of elasticity. Analyses using SEM indicated that HDPE aggregates exhibited low adhesion to the cementitious matrix and mortars with higher HDPE rates improved the energy performance of composite mortars (LWCM).