Lightweight Concrete Made from Waste Polystyrene and Fly Ash

2 Abstract: Concretes containing Portland cement, fly ash as the supplementary cementitious material, natural fine aggregate and a novel lightweight material called Stabilised Polystyrene (SPS)aggregatewere investigated. This paper presents the results of an experimental work on the effects of waste Expanded Polystyrene (EPS) based lightweightaggregate called Stabilised Polystyrene (SPS) and fly ash in concrete. The composite aggregate was formed with 70% waste polystyrene which was shredded to coarse and sand sizes, 10% of anatural material to improve the resistance to segregation of EPS and 20% Portland cement. Nine different mixtureswith water to binder ratio (W/B) of 0.8 with varying SPS content ratios of 0, 60 and 100% as partial replacement of natural fine aggregate by equivalent volume at the fly ash replacement levels of 0, 20 and 40% with Portland cement were prepared and tested. The properties of concrete investigated in this paper were compressive strength and ultrasonic pulse velocity (UPV) at the age of 28-day. The results indicate that there is a decrease in compressive strength and UPV with increasing amounts of SPS and fly ash in concrete. Currently millions of tons of waste polystyrene are increased as EPS bead size decreased and increased as produced in the world. This will ultimately cause pollution the natural coarse aggregate size in concrete increased. and is harmful to the ecosystem. National and The Saradhi Babu et al. (3) study covers the use of international environmental regulations have also expanded polystyrene (EPS) beads as lightweight become more inflexible, causing this waste to become aggregate, both in concrete and mortar. The mechanical increasingly expensive to dispose. Therefore, utilising properties of EPS concretes containing fly ash were waste polystyrene in concrete production not only solves compared to the results of concretes containing Portland the problem of disposing this ultra-light (up to 95% air) cement alone as the binder. The compressive strength of solid waste but also helps preserve natural resources. the EPS concretes containing fly ash show a continuous Sabaa and Ravindrarajah (1) studied engineering gain even up to 90 days, unlike that reported for Portland properties of polystyrene (PS) aggregate concrete by cement in literature. It was also found that the failure of partially replacing natural coarse aggregate with equal these concretes both in compression and split tension volume of the chemically coated polystyrene at the levels was gradual as was observed for the concretes containing of 30, 50 and 70%. They found that compressive strength, plastic shredded aggregates. This study tested mixtures unit weight and modulus of elasticity decreased and with densities as low as 600kg/m . drying shrinkage and creep increased with increasing PS The results of compressive tests in the Miled et al. aggregate replacement in concrete. (4) investigation confirmed the presence of a particle Babu (2) investigated the behaviour of lightweight size effect on the EPS concrete compressive strength expanded polystyrene concrete containing silica fume and since it was observed that the smaller the EPS bead size, found that the rate of strength development increased and the greater the concrete compressive strength, for the the total absorption values decreased with increasing in same concrete porosity. found that the strength of EPS concrete marginally