Mesoscopic Investigation of Conventional and Weakly Bonded Cement Stabilized Macadam Based on Discrete Element...

Road engineers still face a critical challenge in improving the crack resistance of cement-stabilized macadam (CSM) base courses. This study employs the discrete element method (DEM) with realistic aggregate morphologies from X-ray computed tomography to model normally bonded and weakly bonded CSM. The mesoscopic parameters of normally bonded models were calibrated against laboratory unconfined compressive strength (UCS) tests, and a weakening ratio of bond strength (Wr_bs) was introduced to define the weakly bonded model. The results show that UCS decreases monotonically with the reduction in Wr_bs and the increase in Rr_ca. The maximum strength reduction reaches 26.3% at the extreme condition of Rr_ca = 100% and Wr_bs = 50%. Despite this reduction, the UCS of weakly bonded specimens remains compliant with Chinese specifications for base course materials when designed with appropriate parameters. Notably, weakly bonded specimens exhibit a more dispersed crack distribution and a more gradual energy dissipation process. This mechanism is associated with a reduced tendency for macroscopic crack initiation and propagation, suggesting the potential of weakly bonded CSM to enhance crack resistance. This work provides a mesoscopic theoretical foundation for the engineering application and sustainable development of weakly bonded CSM in pavement base courses.