The incorporation of the plastic-coated aggregates into a South African asphalt mixture

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The use of plastic waste in asphalt pavements has been studied internationally. However, only a limited number of studies have been conducted in South Africa that focus on non-recycled plastic waste. This article focuses on the incorporation of LDPE (Low-Density Polythene) plastic waste into South African asphalt mixes via the ‘dry’ modification method. The purpose was to evaluate the effect of LDPE plastic waste on the volumetric and performance properties of an asphalt mixture at optimum bitumen content. Contrary to other research findings, the added LDPE plastic waste did not act as a binder replacement because the bitumen content at the optimum binder content of the asphalt mix remained unchanged after plastic waste addition. Instead, the plastic waste introduced an additional binding effect between the aggregates. The asphalt mix with plastic-coated aggregates (PCA) showed improved resistance to rutting, in line with the improved asphalt stiffness and elasticity at elevated temperatures.