Effect of pretreatment methods on performance of polyurethane recycling asphalt mixture

Abstract

To explore the feasibility of polyurethane used in recycled asphalt mixtures (RAM), the strength and road performance of polyurethane recycled asphalt (PRA) were studied. RAMs were recycled with polyurethane using three treatment methods: RAM with extracted bitumen, RAM with hot mixing treatment, and RAM with hot mixing + rejuvenator, which were named PRA-1, PRA-2, and PRA-3. They were compared with porous polyurethane mixtures (PPM) and open-graded friction course (OGFC) mixtures. Split strength, porosity, anti-freeze capacity, Marshall stability, and adhesion were measured to characterize the performance of mixtures. The results indicate that the performance of PRA-1 is close to that of PPM, which shows good Marshall stability with the split strength of 1.8 MPa. However, the anti-freeze capacity and adhesion property of PRA-1 are lower than those of OGFC. The performance of PRA-2 is close to that of OGFC. The Marshall stability and split strength (1.0 MPa) of PRA-2 are insufficient due to the asphalt, but the anti-freeze capacity and adhesion property are better than those of PRA-1. The strength and stability of PRA-3 are the worst due to asphalt and rejuvenator, which is not recommended in engineering. Therefore, the feasibility of polyurethane used in RAM is closely related to pretreatment methods. The RAM with extracted bitumen and RAM with hot mixing treatment have some application significance. However, it is not recommended to add rejuvenator to PRA. 为研究聚氨酯应用于再生沥青混合料( ＲAM ) 的可行性，研究了聚氨酯再生沥青混合料 ( PＲA) 的强度和路用性能． 对 ＲAM 进行抽提沥青、普通热拌、热拌 + 再生剂预处理后，经聚氨酯 常温再生得到试件 PＲA-1、PＲA-2 和 PＲA-3; 以大孔隙聚氨酯混合料( PPM ) 和开级配抗滑磨耗 层( OGFC ) 为对照，测试 PＲA 的劈裂强度、孔隙率、抗冻性、马歇尔稳定度和抗剥落性． 结果表 明: PＲA-1 的劈裂强度约 1． 8 M Pa，马歇尔稳定度较大，但抗冻和抗剥落性低于 OGFC，性能接近 PPM ; PＲA-2 受沥青影响，劈裂强度( 约 1． 0 M Pa) 和马歇尔稳定度略低，抗冻和抗剥落性优于 PＲA-1，性能接近 OGFC; PＲA-3 受沥青和再生剂影响，强度和稳定度过低，不具有使用意义． 因 此聚氨酯应用于 ＲAM 的可行性与预处理方法密切相关，其中抽提沥青和普通热拌处理方法具 有一定应用意义，但不推荐在 PＲA 中掺入再生剂．