SBS/橡胶粉复合改性SH型混合生物沥青工艺及机理

An investigation of composite modification technology and the mechanism of blended bio-asphalt was performed to improve pavement performance. SH bio-asphalt from a specific source was mixed with petroleum-based asphalt to prepare the blended bio-asphalt, which was then modified by combining styrene-butadiene-styrene (SBS) with crumb rubber (CR). The effects of the modification order and modifier contents on the conventional pavement performance of composite modified asphalt were studied as well as the effects of bio-asphalt content on the swelling properties of modifiers and the high/low-temperature performance of composite modified asphalt. From this, a composite modification technology for blended bio-asphalt was determined. Multiple Stress Creep Recovery (MSCR), Bending Beam Rheometer (BBR), and Frequency Sweep (FS) tests were also performed to evaluate the rheological characteristics of the composite modified asphalt. In addition, chemical functional groups analysis by Infrared Spectroscopy (IR) and micro-topographical characteristics analysis by Fluorescence Microscopy (FM) and Atomic Force Microscopy (AFM) was conducted to reveal the composite modification mechanism of blended bio-asphalt. The results show that the comprehensive pavement performance of the composite modified asphalt with SBS modification (2.5% wt.) before CR modification (18% wt.) is higher than that of the asphalt with SBS modification after CR modification. Both the high/low-temperature performance and modifier swelling properties of composite modified asphalt are excellent with a bio-asphalt content of 15%. Therefore, the composite modification by combining SBS with CR could significantly enhance the high-temperature stability and low-temperature cracking resistance of blended bio-asphalt by increasing the recovery (R) and m-value as well as decreasing the recoverable compliance (Jnr) and creep stiffness (S). These results also correlate with those of complex modulus master curves by FS test. In addition, the network structure of the polymer phase is strengthened owing to the effective solubilization of the polymer modifier by the bio-asphalt addition, thus improving the composite modification effect of the asphalt. Moreover, no new infrared absorption peaks occur in the composite modified asphalt, which implies that this composite modification is a physical process. Furthermore, the comprehensive performance of composite modified asphalt processed in an asphalt factory is better than that of asphalt prepared in a laboratory.