Abstract: Alkali-Activated Slag-Based Engineered Cementitious Composites (AAS-ECC) combines the high toughness advantage of ECC with the rapid hardening, early strength development and low-carbon properties of alkali-activated slag cementitious materials, making it a high-performance repair material with great potential. However, the interfacial bonding mechanism between AAS-ECC and concrete substrate as well as the high-temperature degradation mechanism remain unclear. To address this, 90 composite specimens of ordinary concrete repaired with AAS-ECC were subjected to high-temperature resistance tests, interfacial splitting tensile strength tests after high-temperature exposure, and microscopic analysis tests. The influence mechanisms of AAS-ECC water-binder ratio and matrix strength grade on the interfacial bonding strength of composite specimens under different temperature conditions were investigated. The results show that the interfacial splitting tensile strength of the repaired specimens decreases with the increase of AAS-ECC water-binder ratio. It exhibits a variation law of first increasing and then decreasing with the rise of temperature. Increasing the strength grade of ordinary concrete can enhance the interfacial bonding strength of the repaired specimens. The research results provide data support for the extended application of AAS-ECC in repair engineering and high-temperature environments.

Key words: engineered cementitious composites, patching materials, high temperature, interface splitting tensile strength, micro-analysis