Polyurethane modified asphalt mixture incorporating waste glass with a wide particle size range: Preparation and performance evaluation

Increasing the utilisation rate of waste glass in asphalt mixtures, especially that with a wide range of particle sizes, is of great importance to resource recycling, while it may bring drawbacks to the engineering performance of asphalt mixtures. Incorporating polyurethane (PU) as a modifier can enhance asphalt mixture's performance, but there is limited research considering the usage of waste glass as aggregates. In this study, PU modified asphalt mixtures were prepared, incorporating waste glass particles ranging in size from 2.36 mm to 9.5 mm as a portion of the aggregates. Optimal preparation methods and mix designs for the PU-modified asphalt binder were determined through a series of tests designed based on Orthogonal method. The performances of the PU-modified asphalt binders were then evaluated to guide the selection of the optimal preparation method and mix design. PU-modified waste glass asphalt mixtures were then prepared and their engineering performances were assessed at various glass-to-aggregate ratios. The results show that scheme PU-1 with a shearing temperature of 140°C, a shearing time of 10 min, a PU content of 10% and a compatibiliser content of 2% is suggested for preparing the PU-modified asphalt binder, which shows the best performances due to superior chemical modification and compatibility. Higher glass content decreases the high/low-temperature performance, but it can be improved by adding silane coupling agent or hydrated lime, with the latter showing better results. The incorporation of glass particles has little impact on anti-sliding performance, and asphalt mixtures maintain excellent anti-sliding properties up to a 20% replacement rate. Overall, the performance of the asphalt with waste glass up to 15% can meet the specification requirements. This novel approach offers a potential solution to enhance the incorporation of waste materials in asphalt construction, contributing to sustainable and environmentally-friendly road construction.