Fabrication and application of polyurea formaldehyde-bioasphalt microcapsules as a secondary modifier for the preparation of high self-healing rate SBS modified asphalt

Abstract In this study, microcapsules were prepared from polyurea formaldehyde (as microcapsules wall) and bio-asphalt (as microcapsules core) and were in turn applied to prepare microcapsule-styrene-butadiene styrene (microcapsule/SBS) modified asphalt. When the asphalt wall was broken, the bio-asphalt (core) drifted out and was well blended with the SBS modified asphalt to repair the damaged gap, thereby improving the self-healing ability of the pristine SBS modified asphalt. Ductility test showed that the healing rate of microcapsule/SBS modified asphalt was much greater than that of pure SBS modified asphalt. Dynamic shear rheometer and multi-stress creep recovery tests revealed that microcapsule/SBS modified asphalt exhibited better viscoelasticity, high temperature stability (by thermogravimetric analysis) and rutting resistance than pure SBS modified asphalt attributed to the even dispersion of microcapsules in SBS as confirmed by fluorescent microscopy. Compared with the pure SBS modified asphalt, the storage modulus and loss modulus of 0.4% microcapsule/SBS modified asphalt increased by 24.8% and 17.7% at 46 °C, respectively. Scanning electron microscopy and transmission electron microscopy analyses revealed spherical morphology of the microcapsules with wrinkled depressions on the surface, while the wall of microcapsule coated the core. This study can be envisioned of great promise for the preparation of alternative types of modified asphalt for practical applications in construction and highway industries.