Aging resistance evaluation of asphalt modified by Buton-rock asphalt and bio-oil based on the rheological and microscopic characteristics

Abstract

In order to improve the aging resistance of bio-asphalt, the Buton-rock asphalt (BRA) was selected to modify bio-asphalt. The rheological and Micro-property tests were performed on four types of BRA modified bio-asphalt under different aging degrees. The bio-asphalt with 5% contents of bio-oil was prepared as the base binder. The BRA contents for the four types of BRA modified bio-asphalt were 5%, 10%, 15%, and 20% by weight of the base binder. A series of rheological property tests were performed on BRA modified bio-asphalt with unaged or aged by rolling thin film oven test (RTFOT), or pressure aging vessel (PAV) test for 5 h, 15 h, or 20 h, respectively. The dynamic shear rheometer (DSR) was utilized to reveal the sensitivity of high-temperature properties to aging, including temperature sweep (TS) test at 60 °C and multiple stress creep recovery (MSCR) test at 58 °C. The deterioration of low-temperature performance was demonstrated by the bending beam rheometer (BBR). The effects of aging on the microstructures of the binders were investigated by scanning electron microscopy (SEM). The results show that the BRA improves the high-temperature performance of bio-asphalt, and the higher the content of BRA, the more remarkable the increase is. The BRA modified bio-asphalt is generally more sensitive to aging compared to neat asphalt. The high-temperature properties of BRA modified bio-asphalt with 20% BRA content is equivalent to neat asphalt. The bio-oil greatly improves the low-temperature rheological properties of BRA modified asphalt. The BRA improves the sensitivity of bio-asphalt to aging under low-temperature conditions. The suggested optimal content range of BRA is 15%–20%. The micro-surface of the BRA modified bio-asphalt is flat and has no void structure, crack-free and silver streaks appear after aging. The developed BRA modified bio-asphalt can meet the technical requirements of highway engineering and has outstanding aging resistance. The use of BRA and bio-oil can reduce the consumption of petroleum asphalt, dramatically reduce the cost of materials, and produce exceptional ecological benefits.