Application of the polyurethane foam recycling product as an asphalt extender for sustainable road construction

Polyurethane foam (PUF) is widely used across industries owing to its excellent properties, but it has caused a solid waste stream in the environment. Alcoholysis has been found to be an effective and eco-friendly approach to address this issue. However, substantial by-products are generated in the alcoholysis process, presenting challenges to waste PUF recycling. The by-products of the PUF recycling process (BPF) exhibit similar physical properties to asphalt binder. Therefore, this study uses BPF as an asphalt extender to prepare BPF-asphalt, focusing on its influence on asphalt binder properties. The results show that BPF can greatly maintain or even improve the performance of asphalt binder with good compatibility and workability through physical mixing. The optimum amount is 10 % of the mass of the base asphalt binder. Differences in chemical composition lead to differences in BPF-asphalt properties. Thermal polymerization of polystyrene with small molecular weight in BPF plays an important role in improving the high-temperature performance and fatigue resistance. The presence of diethylene glycol has a negative effect on the performance of BPF-asphalt. This study demonstrates the feasibility of the solution of BPF as an asphalt extender to alleviate the disposal pressure of waste PUF and the consumption of asphalt resources.