ABSTRACT

Blending charts are widely used in the design of recycled asphalt mixes. The amount of recycled binder in the total blend (R/T) can be enhanced by the addition of rejuvenator. The present study investigated two methods of blending approaches. In approach 1, different levels of rejuvenator were added to the recycled binder and R/T was determined for a selected virgin and target binder grade. Approach 2 consisted in determining the rejuvenator content for a selected R/T and virgin binder grade. Nine different binder blends targeted for the same viscosity were synthesised using the two approaches. Blends synthesised using approach 2 accommodated higher R/T. Rutting and oxidative ageing potential of the binder blends was investigated using MSCR experiment and Glower–Rowe’s (G–R) parameter respectively. Blends synthesised using approach 2 exhibited higher non-recoverable creep compliance, poor recovery characteristics and high-stress sensitivity. The rejuvenated recycled asphalt blends endured longer ageing hours before reaching the threshold levels of crack initiation expressed using the G–R parameter. Even though the blending approach 1 incorporated lower levels of RAP than approach 2, from the performance space diagram, it can be found that blends had almost equal rutting and ageing resistance with the target binder grade.

摘要

混合图表广泛用于再生沥青混合料的设计。通过添加再生剂可以提高总混合物中回收粘合剂的量 (R/T)。本研究调查了两种混合方法。在方法 1 中，将不同水平的再生剂添加到回收的粘合剂中，并针对选定的原始和目标粘合剂等级确定 R/T。方法 2 包括确定所选 R/T 和原生粘合剂等级的再生剂含量。使用这两种方法合成了针对相同粘度的九种不同的粘合剂混合物。使用方法 2 合成的混合物适应更高的 R/T。分别使用 MSCR 实验和 Glower–Rowe (G–R) 参数研究了粘合剂共混物的车辙和氧化老化潜力。使用方法 2 合成的共混物表现出更高的不可恢复蠕变顺应性、较差的恢复特性和高应力敏感性。恢复活力的再生沥青混合料在达到使用 G-R 参数表示的裂纹萌生阈值水平之前经受了更长的老化时间。尽管混合方法 1 包含的 RAP 水平低于方法 2，但从性能空间图中可以发现，混合物具有与目标粘合剂等级几乎相等的抗车辙和老化性能。