Acrylate composite polyurethane binder for steel bridge deck pavements: Process optimization by response surface methodology and microanalysis

To better serve the steel bridge deck paving project, a novel room-temperature curing acrylate composite polyurethane binder (APUB) was developed as a substitute for traditional asphalt binders. APUB was synthesized by the copolymerization of a custom-made polyurethane prepolymer (BDO-PU) and acrylate. Fourier transformed infrared and proton nuclear magnetic resonance spectroscopy analyses confirmed the presence of carbamate structures in prepolymer BDO-PU. Utilizing tensile strength, breaking elongation and water absorption as optimization criteria, the response surface methodology was used to optimize synthesis process of APUB. The results showed that the optimized parameters for APUB synthesis include an isocyanate index (R) of 1.5, a mass ratio of methyl methacrylate to BDO-PU of 1.1, and a curing agent content of 2.7%. These settings resulted in predicted values of 10.12 MPa for tensile strength, 123.85% for breaking elongation, and 0.075% for water absorption. Experimental validation demonstrated the consistency between the predicted and actual properties of APUB. Further microanalyses, including dynamic mechanical thermal analysis, differential scanning calorimetry, and scanning electron microscope, confirmed APUB exhibits excellent component compatibility and glass transition temperatures suitable for bridge engineering environments. Overall, APUB demonstrates outstanding tensile properties, water resistance, low energy consumption, and potential applications in the steel bridge deck pavement industry.