Comparison of material properties of lightweight concrete with recycled polyethylene and expanded clay aggregates

Abstract

The article discusses the possibility of using high and low density polyethylene waste as aggregate in lightweight concrete with high strength cement mortar. Research is dedicated to experimental investigation and comparison of material properties of concrete made of polyethylene waste and expanded clay aggregates. Hydration kinetics studies of concrete specimens with different aggregates are performed using measurements of ultrasonic pulse velocity. For the experimental investigation high and low density polyethylene plastic waste aggregates with low water absorption and hydrophobic surface were used. It is stated that concrete with low water absorption plastic waste aggregates after 7 days of curing showed significant decrease in strength growth rate. The specimens had a density of 1950 – 2050 kg/m3 with a compressive strength of at least 40 MPa. Using pre-wetted expanded clay aggregate with similar mix composition, concrete density was 1900 kg/m3 with a compressive strength up to 70.2 MPa. Although having similar mechanical properties as the waste plastic aggregate, pre-wetted expanded clay allows better cement hydration process, resulting in lower water absorption of lightweight concrete.