Effect of dynamic vulcanization on the performance of high content rubber modified asphalt

High content rubber modified asphalt (HCRA) is usually prepared with devulcanized rubber (DR) in asphalt with good workability. However, the high-temperature properties of HCRA deteriorate simultaneously. In this study, dynamic vulcanization approach was adopted to improve the high-temperature properties of HCRA without mitigating the workability and low-temperature performance of modified binder blends. The dynamic vulcanization process and mechanism were investigated based on the gel content, related chemical reactions, morphology, rheological behavior, and tensile properties of HCRA. The occurrence of dynamic vulcanization was confirmed by the increase in gel content. Fourier transform infrared spectroscopy reflected that C(sic)C bonds in trans-olefins participated in dynamic vulcanization, followed by the reaction of those in conjugated olefins. Optical microscopy tests showed that dynamic vulcanization also improved the compatibility between the DR and asphalt. It was found that dynamic vulcanization of HCRA is the gradual stabilization process to form local cross-linked networks in asphalt. With the addition of sulfur, degradation, aging, and dynamic vulcanization took place simultaneously in HCRA. Dynamic vulcanization increased the high-temperature properties, fracture toughness, as well as storage stability of HCRA. Furthermore, dynamic vulcanization restricted rubber degradation and improved the aging behavior of HCRA.