Evolution of aggregate skeleton in asphalt mixture at meso-scale by DEM and topology

Asphalt mixture, the most common material used for road surfacing, is prone to various forms of distresses, such as rutting and fatigue. In asphalt mixtures, the aggregate skeleton acts as the primary load-bearing structure. However, its structural changes are challenging to quantify at the macro scale. In this study, aggregates were classified into three categories: disruption aggregate (DA), main skeleton aggregate (MSA) and central large aggregate (CLA). Then, algebraic connectivity (La), effective average coordination number (Kn) and clustering coefficient (Ci) were used to quantitatively characterise their structural properties. Furthermore, an uniaxial compression test was conducted using DEM to analyse structural evolution of the aggregate skeleton at three stages: initial loading, peak stress and failure. It was found that during loading, DA contacts were lost, weakening inter-particle connections; MSA saw a decrease in Kn and an increase in unstable particle proportion, reducing bearing capacity; and CLA experienced a decline in local aggregation, damaging structural uniformity, all leading to progressive failure. This study analysed the evolution of the aggregate skeleton structure under uniaxial compressive loading and evaluated the progressive failure of the inter-particle contact structure throughout the loading process.