Fabrication of urea formaldehyde–epoxy resin microcapsules for the preparation of high self-healing ability containing SBS modified asphalt

Asphalt exhibits self-healing ability, though at a lower rate. In this study, urea formaldehyde–epoxy resin (UFE) microcapsules were prepared using polyurea formaldehyde as the wall and epoxy resin as the core material, which were in turn applied to fabricate UFE–styrene butadiene styrene modified asphalt (abbreviated as UBS asphalt). Scanning electron microscopy and transmission electron microscopy analyses revealed well-coated microcapsules have globular geometry with obvious folds in the wall. Ductility test showed 90% higher healing rate of UBS asphalt than pure styrene butadiene styrene (SBS) modified asphalt. Dynamic shear rheometer and multi-stress creep recovery tests indicated that UFE microcapsule incorporation can improve the viscoelasticity, high temperature stability, and permanent deformation resistance of pure SBS modified asphalt attributed to the even distribution of UFE microcapsules in asphalt and their better mutual compatibility, which was confirmed by fluorescence microscopy. At 100 and 3200 Pa, the recovery rate of 0.4% UBS asphalt was 32.1% and 71.7% higher than that of the original SBS modified asphalt, respectively. UFE microcapsule and asphalt only physically interacted as confirmed by Fourier infrared spectroscopy analysis. This study provides a feasible alternative approach for the preparation of UBS asphalt with enhanced mechanical properties and thermal stability for applications in construction and highway industries.