More effective and sustainable use of natural resources besides the mitigation of environmental impacts induced by their extraction could be achieved by reusing construction and demolition (C&D) materials. C&D materials are increasingly being used in pavement bases/subbases as a reliable alternative to virgin quarry materials. The behaviour of flexible pavements under dynamic loads conveyed from traffic load can be evaluated in the laboratory by the repeated load triaxial test (RLT). This research study aims to evaluate the macro- and micro-mechanical interaction and underlying mechanisms of the behaviour of unbound recycled concrete aggregate (RCA) materials under RLT test using discrete element method (DEM) and to compare the simulated results with experimental results. In this research a DEM numerical software was used to develop a novel stress-controlled test method for modelling the RLT test, using a flexible membrane boundary with spherical particles linked through linear contact model. During the simulation, the axial recoverable deformations were monitored to determine the resilient modulus (M_R) at each of the 16 loading-unloading stress level sequences. Furthermore, the micro-mechanics of the RCA samples were investigated using anisotropy tensor of fabric, contact orientation, contact force network and coordination number (CN). Laboratory RLT tests were conducted to verify the robustness of the DEM model. In general, both quantitative and qualitative agreements were attained between the physical tests and the numerical DEM simulations. The results of the micro-scale analyses revealed that the response of the RCA sample during the cyclic test was almost elastic. In other words, the almost-elastic behaviour was not accompanied by a significant change in the material fabric, rather was accompanied by a variation in the magnitude of the contact forces without variation in the contact force network and CN.

除了减轻自然资源开采带来的环境影响外，还可以通过重复使用建筑和拆除（C＆D）材料来实现对自然资源的更有效和可持续的利用。C＆D材料正越来越多地被用作人行道采石场材料的可靠替代品。可以在实验室中通过反复载荷三轴试验（RLT）来评估在由交通载荷传递的动态载荷下的柔性路面性能。这项研究旨在评估使用离散元方法（DEM）在RLT试验下未结合的再生混凝土骨料（RCA）材料的宏观和微观力学相互作用以及其行为的潜在机理，并将模拟结果与实验结果进行比较。在这项研究中，使用DEM数值软件开发了一种新的应力控制测试方法，该方法用于模拟RLT测试，该方法使用带有通过线性接触模型链接的球形颗粒的柔性膜边界。在模拟过程中，监测轴向可恢复变形以确定弹性模量（M_R）在16个加载-卸载应力水平序列中的每个序列上。此外，使用织物的各向异性张量，接触取向，接触力网络和配位数（CN）研究了RCA样品的微观力学。进行了实验室RLT测试以验证DEM模型的鲁棒性。通常，物理测试和数值DEM模拟之间都获得了定量和定性的协议。微观分析结果表明，RCA样品在循环测试过程中的响应几乎是弹性的。换句话说，几乎弹性的行为没有伴随着材料织物的显着变化，而是伴随着接触力大小的变化而没有接触力网络和CN的变化。