Toughening epoxy asphalt binder using core-shell rubber nanoparticles

Abstract Core-shell rubber (CSR) has been widely applied in the improvement of the toughness for the brittle epoxy resin. In this study, an epoxy asphalt (EA) binder has been toughened by the inclusion of CSR nanoparticles with approximately 100–200 nm in diameter. The incorporation of CSR nanoparticles significantly increased the viscosity of the pure EA during curing. Even with 5 wt% CSR, the EA blend exhibited extremely long operational lifetime (more than 2.5 h) for mixture pavements. The glassy shell of CSR nanoparticles was broken and the rubbery core of CSR nanoparticles swelled in the EA. New micro-scale CSR domains formed and uniformly dispersed in the epoxy phase of the cured EA. The inclusion of CSR nanoparticles altered the phase separation mechanism of the pure EA. The sea-island morphology of the pure EA took place through the nucleation and growth (NG) mechanism, while co-continuous microstructures in the EA blends with 3 wt% and 5 wt% CSR formed through the spinodal decomposition (SD) mechanism. Both sea-island and co-continuous microstructures via combined the NG and SD mechanisms were observed in the EA blend containing 1 wt% CSR. The glass transition temperature and thermal stability of the pure EA was improved by the inclusion of higher CSR loadings. The incorporation of CSR greatly enhanced the mechanical properties of the pure EA. In the case of 1 wt% CSR inclusion, 29% increase in the tensile strength, 60% improvement in the elongation at break and 2-fold increment in the toughness were obtained.