Utilization of Plastic Waste in Fly Ash Geopolymer Concrete Containing Recycled Concrete Aggregate for Pavements

In this paper, the utilization of waste plastic to enhance the flexural properties of fly ash geopolymer concrete containing recycled concrete aggregate (RCA) was investigated. The mechanical and physical properties of the concrete were studied. Three types of waste plastic, viz., polypropylene (PP) beads, polyvinyl chloride (PVC) and polyethylene terephthalate (PET) scraps, were incorporated in the fly ash geopolymer concrete which contained recycled concrete aggregate. The incorporation of plastic waste slightly reduced the compressive strength of the geopolymer concrete containing recycled concrete aggregate. The incorporation of PP beads increased the flexural strength by 12–21% of the control concrete. However, the flexural strength of the mixes containing PVC and PET aggregates were slightly reduced compared to the control. The incorporation of plastic wastes also reduced the modulus of elasticity by 13–24% from conventional concrete. The water absorption and porosity increased with an increased amount of waste plastic. In addition, the incorporation of recycled plastic improved the surface abrasion resistance, thermal resistance, and thermal insulation properties of concrete. The flexural strength of mixes with PP beads and mixes with a moderate amount of PVC and PET met the requirements for pavement standards with a reduced modulus of elasticity and improved surface abrasion and thermal resistance.