LAUSR

Abstract Block cracking is a thermally-induced damage occurring in asphalt pavements. The mechanism behind the formation of this type of cracking has not been fully investigated to date. The present work focuses on developing a series of two-dimensional viscoelastic and heterogeneous micromechanical-based discrete element models to investigate the formation of block cracking in asphalt pavements subjected to thermal loads. Several different block cracking patterns are explored by varying both material properties and thermal conditions. These properties include the dimensions of pavement segments, stress relaxation capacity and aging state of the asphalt materials, spatial aging and thermal properties gradients, cooling rates and pre-existing cracks. It is observed that formation of block cracking can be separated into two steps: (1) initiation of microcracks, followed by (2) the coalescence of microcracks and channeling of macrocracks. Results showed that when microcracks propagate in a symmetric or infinitely large pavement segment, they tend to develop in arbitrary directions to form a Y-junction pattern. When growing cracks intersect, they tend to join at right angles. In general, block cracking can be categorized by its reoccurring geometrical pattern. These cracks coalesce forming rectangular and hexagonal cracks. In this study, discrete element simulation results showed that both rectangular and hexagonal shaped cracking could occur under the same assumption. It was also observed that block cracking primarily occurs in the upper one-to-two centimeters of the top material layer, which is consistent with field observations.