The modification mechanisms of silane coupling agent (SCA) on the physical properties of thermosetting polyurethane asphalt binder (PUAB)

Abstract

• The addition of SCA enhanced the physical properties of PUAB . • A viscosity model based on the dual-Arrhenius theory was established. • SCA had physical and chemical connection on the polyurethane-asphalt interface. • A deformation layer formed by SCA was a significant role in PUAB system. The paper attends to investigate the influence of silane coupling agent ( SCA ) on the novel thermosetting polyurethane ( PU ) asphalt binder ( PUAB ). Initially, the storage stability, thermal stability and viscosity of PUAB are evaluated with the separation test, thermogravimetric analysis ( TGA ) and Brookfield viscosity, respectively. Then the mechanical properties, elastic recovery performance and permanent deformation resistance of PUAB are examined by the universal testing machines and dynamic shear rheometer ( DSR ), respectively. Finally, the modification mechanism is analyzed by Fourier transform infrared spectroscopy ( FTIR ). The results show that the thermal stability and storage stability of PUAB are improved by adding SCA . Then, a viscosity model based on the dual-Arrhenius theory is established and well predicts the effect of SCA on viscosity-time relationship of PUAB . Furthermore, the addition of SCA significantly enhance mechanical behaviors of PUAB where the complex modulus of PUAB rise, a 16 % of tensile strength increase and a 98.4 % of the elastic recovery (58 °C/0.1 kPa) are reached with 1 % SCA adding. Data from chemical investigations suggest that SCA connect between asphalt and PU to form groups of oxazolidinone, then promoting better compatibility. Then formed deformation layer can relieve the stress and improve the interfacial bond strength. Accordingly, this finding provides a feasible approach to the performance improvement of PUAB .