Fracture characteristics of cement-stabilized macadam using three-point bending test

Semi-rigid base is the main component of highway pavements in China and is prone to cracking damage under vehicle loading and environmental effects. In this paper, three-point bending (TPB) tests on prefabricated cracked specimens of CSM beams were conducted to study the damage evolution and fracture characteristics of cement-stabilized macadam (CSM) under different loading rates. The acoustic emission (AE) technique and scanning electron microscope (SEM) analysis were utilized. The results indicate that the fracture energy and fracture toughness of CSM were enhanced at increasing loading rates, and the amplitude distribution of AE events became wider and more energetic. The damage modes of CSM can be classified into interface transition zone (ITZ) damage, cement mortar damage, and aggregate damage. The fracture surfaces were mainly ITZ damage. The brittle structure of CSM was caused by incomplete hydration of cement particles in ITZ. This study can provide a better understanding of the fracture mechanism of CSM at different loading rates. The findings can also guide the design, construction, operation and maintenance of semi-rigid roadbed pavement structures.