ABSTRACT

The mechanical performance of asphalt mixtures with high air void content – like Permeable Friction Courses (PFC) – is significantly affected by climate-related processes. Previous studies have demonstrated that ravelling (i.e. the loss of aggregates from the surface of the PFC) is related to the quality of the stone-on-stone contacts within the microstructure of these mixtures. Since the material located at these contacts is asphalt mortar, the durability of the mixtures strongly depends on the mechanical properties of this phase. This paper evaluates, for the first time, the coupled effects of ageing and moisture on the mechanical and fracture properties of the asphalt mortar of a typical PFC. The climatic conditioning processes included short and long-term ageing and dry-wet-dry moisture vapour cycles. The linear viscoelastic and fracture properties of the PFC mortar specimens were characterised using Dynamic Mechanical Analyser (DMA) and Semi-Circular Bending (SCB) tests. The results showed that ageing impacted the dynamic modulus of the mortar, while moisture had a negligible effect on this property. Also, the coupled effects of long-term ageing and moisture cycles reduced the fracture energy and other fracture parameters of the mortar between 2 and 10 times with respect to the short-term ageing condition in dry state.

摘要

具有高空隙率的沥青混合物的机械性能——如渗透摩擦过程 (PFC)——受到气候相关过程的显着影响。先前的研究表明，散开（即 PFC 表面的骨料损失）与这些混合物的微观结构内的石对石接触的质量有关。由于位于这些接触点的材料是沥青砂浆，因此混合物的耐久性很大程度上取决于该相的机械性能。本文首次评估了老化和水分对典型 PFC 沥青砂浆的力学和断裂性能的耦合影响。气候调节过程包括短期和长期老化和干-湿-干湿气循环。使用动态机械分析仪 (DMA) 和半圆弯曲 (SCB) 测试来表征 PFC 砂浆试样的线性粘弹性和断裂性能。结果表明，老化影响砂浆的动态模量，而水分对此性能的影响可以忽略不计。此外，长期老化和水分循环的耦合作用使砂浆的断裂能和其他断裂参数相对于干燥状态下的短期老化条件降低了 2 到 10 倍。