ABSTRACT

The effects of polymer modification on the durability of Polymer Modified Bitumens (PMBs) still remain relatively unclear due to partial understanding of the combined effects of ageing and loading on damage accumulation. This paper investigates the effects of laboratory ageing on the damage tolerance of cross-linked SBS and EVA modified bitumens measured using the Linear Amplitude Sweep (LAS) test and corroborated with the morphology of the PMBs. The PMBs were prepared with three polymer concentrations (i.e. 2%, 4% and 6%). In general, ageing affects the capacity of bitumens to maintain integrity to damage and reduces their time-temperature susceptibility. The damage tolerance is derived from the combination of the two mechanisms as a function of the bitumen’s strain level. At low strain levels, typical of thick pavements, ageing enhances the damage tolerance. Contrarily, at higher strain levels, it provides the opposite effect. SBS improves the damage tolerance of the base bitumen as a function of polymer concentration and dispersion. However, the polymer chain undergoes oxidative degradation and its effect reduces with ageing. EVA forms a polymer network with a low oxidative susceptibility that contributes, at low strain, to maintaining or improving the damage tolerance with ageing as a function of the polymer concentration.

摘要

由于对老化和负载对损伤累积的综合影响的部分了解，聚合物改性对聚合物改性沥青 (PMB) 耐久性的影响仍然相对不清楚。本文研究了实验室老化对使用线性振幅扫描 (LAS) 测试测量的交联 SBS 和 EVA 改性沥青的损伤容限的影响，并证实了 PMB 的形态。用三种聚合物浓度（即 2%、4% 和 6%）制备 PMB。一般来说，老化会影响沥青保持完整性以防损坏的能力，并降低其时间-温度敏感性。损伤容限源自两种机制的组合，作为沥青应变水平的函数。在低应变水平下，典型的厚路面，老化增强了损伤耐受性。相反，在更高的应变水平下，它提供了相反的效果。SBS 提高了基础沥青的损伤容限，作为聚合物浓度和分散的函数。然而，聚合物链会发生氧化降解，其效果会随着老化而降低。EVA 形成具有低氧化敏感性的聚合物网络，该网络有助于在低应变下保持或提高随聚合物浓度变化的老化损伤容限。