Preparation and performance study of PPA-REOB composite modified bitumen

Abstract

To efficiently REOB and address the technical challenge of improving the low-temperature performance of PPAMB, this study investigates the preparation and performance of composite modified bitumen using REOB and PPA as additives. The micro-mechanisms and macroscopic properties of the composite modified bitumen were systematically studied. First, the optimal contents of REOB and PPA were determined based on fundamental performance indicators. Second, the modification mechanisms of REOB and PPA on bitumen were revealed through micro-analysis techniques, including XRF, SARA fractionation, infrared spectroscopy, and FM. Third, the effects of PPA and REOB on the macroscopic performance of bitumen were evaluated using DSR, BBR tests, and adhesion tests. Finally, the macro-level road performance of PPA-REOB MB mixtures was compared with PPAMB mixtures to validate the findings. The results indicate that the optimal contents of PPA and REOB are 0.5 % and 1.8 %, respectively, yielding the best fundamental indicators for PPA-REOB MB. REOB can disperse and solubilize heavy fractions in bitumen, primarily promoting the transition of the bitumen system to a sol structure through physical interactions. This significantly enhances the low-temperature performance of PPAMB, reducing its stiffness modulus (S) at −6°C by 26.4 % and increasing its creep rate (m-value) by 12 %. However, REOB also slightly decreases the high-temperature performance of PPAMB, with a 19.97 % reduction in rutting factor at 76°C and a 1.55 % increase in phase angle, although the performance remains notably superior to that of matrix bitumen. Furthermore, the adhesion rate of PPA-REOB MB improves by 14.13 % compared to matrix bitumen but decreases by 5.5 % compared to PPAMB. PPA-REOB MB mixtures exhibit significantly better low-temperature performance than PPAMB mixtures, although with a slight reduction in high-temperature performance.