ABSTRACT

Macro-scale fractures of asphalt mixture usually exhibit multiple failure mechanisms including aggregate cracking, interfacial debonding between bitumen and aggregate, and binder tearing; however, damage modelling through conventional continuum mechanics fails to take into consideration the effects of the small-scale physical phenomena. This study aims to introduce a micromechanical damage model for a fundamental understanding of interfacial debonding in asphalt mixtures. The bilinear Cohesive Zone Model (CZM) was incorporated into the Mori-Tanaka model and the constitutive behaviour of asphalt mixtures was predicted. The results show that the interfacial debonding exhibit a significant dependency on aggregate size. A critical aggregate size was identified, above which the damage behaviour of asphalt mixtures changes from hardening to softening. The critical aggregate size increases withmortar modulus but decreases with softening interfacial stiffness, Poisson’s ratio of the mortar and aggregate volume fraction. The interface strength and the fracture energy also have a significant effect on the fracture behaviour of asphalt mixtures. The strength of asphalt mixtures increases as the interface strength increases; it is independent of the fracture energy. Increased fracture energy can improve the fracture resistance of the asphalt mixture, while increased interface strength has an opposite effect.

摘要

沥青混合料宏观断裂通常表现出骨料开裂、沥青与骨料界面剥离、粘结剂撕裂等多种破坏机制；然而，通过传统的连续介质力学进行的损伤建模没有考虑到小尺度物理现象的影响。本研究旨在介绍一种微机械损伤模型，以便从根本上了解沥青混合物中的界面剥离。将双线性内聚区模型 (CZM) 纳入 Mori-Tanaka 模型，预测沥青混合料的本构行为。结果表明，界面剥离表现出对聚集体尺寸的显着依赖性。确定了一个临界骨料尺寸，超过该尺寸沥青混合料的破坏行为会从硬化变为软化。临界骨料尺寸随着砂浆模量的增加而增加，但随着界面刚度、砂浆和骨料体积分数的泊松比的软化而减小。界面强度和断裂能对沥青混合料的断裂行为也有显着影响。沥青混合料的强度随着界面强度的增加而增加；它与断裂能无关。增加的断裂能可以提高沥青混合料的抗断裂性，而增加的界面强度则具有相反的效果。沥青混合料的强度随着界面强度的增加而增加；它与断裂能无关。增加的断裂能可以提高沥青混合料的抗断裂性，而增加的界面强度则具有相反的效果。沥青混合料的强度随着界面强度的增加而增加；它与断裂能无关。增加的断裂能可以提高沥青混合料的抗断裂性，而增加的界面强度则具有相反的效果。