Damage Mechanisms of Cement–Asphalt Interface Within Semi‐Flexible Pavement Materials Under Fatigue State

ABSTRACT Semi‐flexible pavement material (SFPM) is an asphalt paving composite that incorporates cement‐based grout injected into the large voids of asphalt concrete. The damage to the interface under fatigue conditions is a primary concern for SFPM, primarily due to the weak interfacial bonding between cement and asphalt. Therefore, it is essential to understand the damage mechanisms of the cement–asphalt interface under fatigue conditions. The fatigue characteristics of SFPM are investigated using semi‐circular bending tests. Subsequently, microscopic damage mechanisms are examined through scanning electron microscopy, energy dispersive spectroscopy, and nanoindentation tests. The effects of asphalt binder and interfacial modifiers on interface damage are also analyzed. Results indicate that high‐viscosity asphalt exhibits the optimal interfacial thickness, strong adhesion, a minimal number of interfacial micropores, high interfacial strength, and superior fatigue resistance. Additionally, the incorporation of emulsified asphalt promotes the continuous precipitation of hydration products within the asphalt phase, thereby enhancing fatigue resistance.