Development of porous asphalt mixture based on the synthesis of PTEMG and MDI polyurethane asphalt

Polyurethane-modified asphalt (PA) stands out as an environmentally sustainable road material, renowned for its exceptional performance that significantly extends road surface lifespans while reducing maintenance costs. This study focuses on the preparation of PA using a single-component blending method that incorporates polyether polyol PTEMG (Poly-(tetra methylene ether glycol)) and isocyanate MDI (4,4 '-diphenylmethane diisocyanate) as primary raw materials. Various analytical techniques, including Fluorescence Microscopy, Fourier-transform Infrared Spectroscopy (FTIR), Thermogravimetric analysis (TG), Differential Scanning Calorimetry (DSC), Vis-cosity Testing, Tensile Testing, and Bending Beam Rheometer (BBR), were employed to investigate PA's microstructure, modification mechanism, thermal properties, viscosity characteristics, curing properties, and low-temperature stability. A porous polyurethane-modified asphalt mixture, targeting a void content of 20%, was designed and compared to a high-viscosity modified asphalt mixture with the same void content in terms of performance. The results indicate a combination of chemical and physical processes in PA modification. Through TG and DSC experiments, it was ascertained that polyurethane-modified asphalt commences decomposition at 252 degrees C, exhibiting an exothermic peak within the temperature range of -19.98-2.73 degrees C. The introduction of polyurethane substantially enhances the thermal performance and cryogenic stability of the asphalt binder. Viscosity tests and tensile experiments indicate that the curing reaction of polyurethane-modified asphalt is protracted and irreversible. Consequently, it is recommended to prepare polyurethane-modified asphalt mixtures employing a compaction temperature of 175 degrees C and a maximum resting time of 100 min. Additionally, specimens should rest at room temperature for at least 3 days. Comparatively, the porous asphalt incorporating poly-urethane exhibits notable advantages over the high-viscosity modified asphalt mixture. It demonstrates superior high-temperature stability, excellent resistance to low-temperature cracking, reduced sensitivity to strains, prolonged fatigue life, and improved flexibility. However, its fatigue resistance and resistance to dynamic loads are slightly inferior. This study offers valuable insights into the use of polyurethane in porous asphalt mixtures, making it a promising option for sustainable road construction.