Improvement on the mechanical properties of CA mortar and concrete composite specimens in high-speed railway by modification of interlayer bonding

In this study, polymer latex and expansive agent were employed to modify the interfacial bonding relationship between cement asphalt mortar (CA mortar) and concrete in high-speed railway. The mechanical properties of composite specimens with different interlayer bonding were systematically investigated by testing their flexural strength and failure modes. The effects of temperature on the mechanical properties of the composite specimens were also discussed. Results indicated that the addition of both polymer latex and expansive agent increased the interfacial bonding strength owing to their improvement on microstructure. Due to the increase of interlayer bonding, the failure modes of composite specimens transformed from an incompatible failure to a compatible failure, and their flexural strength significantly increased. The effects of polymer latex on the mechanical properties were greater at a higher mass ratio of asphalt to cement (A/C) whereas the effects of expansive agent were larger at a lower A/C. After temperature cycles, the composite specimens presented the incompatible failure mode and their flexural strength dropped sharply. The presence of expansive agent aggravated the temperature effects. In contrast, polymer latex weakened the temperature effects due to its superior modifications on interlayer bonding at high A/C values. It is believed that polymer latex and expansive agent can be selectively used in practice to enhance the mechanical properties and the serviceability of slab track. (C) 2019 Elsevier Ltd. All rights reserved.