Preparation And Application Of Polyurethane For Rapid Maintenance Of Road Pavement

Highway transportation infrastructure is the foundation and lifeline of national economic development,and asphalt pavement accounts for more than90% of China’s highways.Affected by load fatigue and environmental changes,asphalt pavement will have rutting,cracks,potholes and other diseases,which need to be repaired in time to eliminate safety hazards and reduce economic losses.Therefore,this paper aims to develop polyurethane materials for rapid pavement maintenance.The synthesis and characterization of polyurethane resin,the preparation and performance evaluation of polyurethane mixes,and the construction verification of polyurethane mixes are used as the technical routes.Vegetable oil-based two-component polyurethane(VODPU)was synthesized by one-step process using modified diphenylmethane diisocyanate(L-MDI),Vegetable oil(VO)and Chain extender(BH91)as raw materials,and its crushed stone mixture(VODPUM)was prepared.The effects of hard segment content,isocyanate index,and Vegetable oil functionality on the performance of VODPU and VODPUM were studied.Vegetable oil-based single-component polyurethane(VOSPU)was synthesized by a prepolymerization method using diphenylmethane diisocyanate(MDI),modified Vegetable oil,and oxazolidine-based latent curing agents as the raw materials,and its crushed stone mixture(VOSPUM)was prepared.The effects of-NCO content on the performance of VOSPU and VOSPUM were studied and the conclusions were as follows:(1)When the hard segment content was 45%,isocyanate index was 1.05,and Vegetable oil functionality was 2.7,VODPU and VODPUM had the best overall performance.The tensile strength of VODPU was 28.64 MPa,elongation at break was 134.4%,saturated water absorption was 0.453%,heatresistant tensile strength retention was 95.95%,and water-resistant tensile strength retention was 69.44%.The Marshall stability of VODPUM(VODPU added at 6%)reached 9.124 k N at 1 hour of molding,the standard and freezethaw splitting strengths were 2.372 MPa and 1.108 MPa,respectively,and the standard and soaked flyaway mass loss rates were 3.562% and 6.464%,respectively.The applicability of VODPUM to the rapid maintenance of asphalt pavements on sunny days was verified by actual pavement repair.(2)VOSPU achieves the underwater bonding of crushed stone aggregate,and the comprehensive performance of VOSPU and VOSPUM were optimal when the-NCO content was 12%.The tensile strength of VOSPU was 22.95 MPa,the elongation at break was 171.0%,the saturated water absorption was3.490%,and the underwater shear strength was 2.752 MPa,which was 1.163 MPa higher than the shear strength in air.The splitting strength of VOSPUM at1 h of underwater forming was 1.492 MPa,and the standard and submerged flyaway mass loss rates were 3.204% and 2.870%,respectively.The applicability of VOSPUM to the rapid maintenance of asphalt pavements on rainy days was verified by actual pavement repair.