Utilization of crumb rubber as aggregate in high calcium fly ash geopolymer mortars

Abstract

This research was carried out to find out the possibility of utilizing tire crumb rubber waste as fine aggregate in fly ash-based geopolymer mortars (GPMs). The effect of replacement of river sand with crumb rubber at the levels of 0, 25, 50, 75, and 100% by volume on the geopolymer mortar properties including workability, dry density, compressive strength, flexural strength, thermal conductivity, ultrasonic pulse velocity (UPV), water absorption, and porosity were studied. The results were compared to those of the Portland cement-based mortars (PCMs). The test results demonstrated that the higher crumb rubber content resulted in the less dense matrix of mortar. However, GPMs with crumb rubber resulted in a significant improvement in flexural strength. The average ratio of flexural to compressive strengths of GPMs was 25% compared to 15% of PCMs. Also, the lower dry density and thermal conductivity of GPMs indicated better insulating properties than those of PCMs.