Recycled Non-Biodegradable polyethylene terephthalate waste as fine aggregate in fly ash geopolymer and cement mortars

Abstract

In this study, the use of recycled non-biodegradable polyethylene terephthalate (PET) waste as a fine aggregate in fly ash geopolymer mortar was examined. PET waste was used to replace 0%, 10%, 20%, 30%, and 40% by volume of natural fine aggregate for preparing geopolymer mortar. The flow, density, porosity, water absorption, ultrasonic pulse velocity (UPV), thermal conductivity, and strengths of the mortars were tested and compared with those of ordinary Portland cement (OPC) mortar. The results showed that the mechanical properties of the geopolymer mortar deteriorated with an increase in the amount of PET waste. The compressive strength decreased from 42.7 to 12.8 MPa with increasing PET content from 0 to 40% for geopolymer mortars and decreased from 49.5 to 22.5 MPa with increasing PET content from 0 to 20% for cement mortars. However, the ratio of flexural strength to compressive strength of geopolymer and cement mortars containing PET waste tended to improve. In addition, the density and thermal conductivity were significantly reduced with increasing PET content; ranging from 1585 to 2020 kg/m3 and 0.6329 to 1.3116 W/m.K, respectively for geopolymer mortar and from 1763 to 2042 kg/m3 and 1.181 to 2.0030 W/m.K, respectively for cement mortar. The reduction of density and thermal conductivity in both types of mortar could be used to reduce self-weight and improve thermal performance.