Study on interlayer bonding strength and fatigue performance between cement asphalt mortar and track slab

Interlayer debonding between cement-asphalt mortar (CAM) and the track slab (TS) is a major distress in China Railway Track System-II (CRTS-II) slab ballastless tracks. Based on the actual loading mode of the CAM-TS interface under train loads, inclined shear, deep-beam bending and three-point bending fatigue tests were conducted to investigate interlayer bonding and fatigue performance. A trilinear model describing the interfacial bonding behaviour was established, and the effects of emulsified asphalt-to-cement mass ratio (A/C), temperature, loading rate, stress level and debonding length were evaluated. Shear and flexural-tensile hardening were observed, and the trilinear model effectively described the interlayer bonding behaviour. A/C was the dominant factor affecting shear and flexural-tensile strength, whereas debonding length was the dominant factor affecting fatigue life. An A/C of 0.5 provided relatively favourable interlayer bonding performance, and timely repair is recommended once interlayer debonding occurs.