ABSTRACT

Porous asphalt concrete (PAC) constitutes large air voids and coarse aggregate, forming a unique aggregate structure. The open pore structure is advantageous in creating space for stormwater runoff to infiltrate into an underground basin and reduce tyre-road noise. However, this aggregate structure compromises the load-carrying capacity and deformation resistance of the mixture. Achieving balance between permeability and bearing capacity of PAC has been a major concern. This study evaluates effects of the aggregate structure on bearing capacity and the deformation resistance of PAC. Gradation-based framework was first applied to examine different gradations of PAC. Discrete-element models of PAC with varying gradations were developed to evaluate its performance and characteristics of aggregate skeleton. A laboratory wheel track test was conducted to validate findings from the DEM analysis. It was found that gradation that meets the interlock check of the framework produced a mixture with optimal performance. More coarse aggregate provides additional strength but lacks sufficient smaller-sized particles to form a new skeleton when it breaks down. More fine aggregate diminishes the load-carrying capacity and deformation resistance of the mixture as no stable skeleton could be formed.

摘要

多孔沥青混凝土（PAC）由大孔隙和粗骨料构成，形成独特的骨料结构。开孔结构有利于为雨水径流创造空间以渗入地下盆地并降低轮胎路面噪音。然而，这种骨料结构损害了混合物的承载能力和抗变形能力。实现 PAC 的渗透性和承载能力之间的平衡一直是一个主要问题。本研究评估了骨料结构对 PAC 的承载能力和抗变形能力的影响。基于等级的框架首先应用于检查不同等级的 PAC。开发了具有不同等级的 PAC 的离散元模型，以评估其性能和聚合骨架的特性。进行了实验室轮轨测试以验证 DEM 分析的结果。发现满足框架联锁检查的级配产生了具有最佳性能的混合物。更粗的骨料提供了额外的强度，但在分解时缺乏足够的较小尺寸的颗粒来形成新的骨架。更细的骨料会降低混合物的承载能力和抗变形能力，因为不能形成稳定的骨架。