Durability of self-healing ultra-high-strength reinforced micro-concrete under freeze-thaw or chloride attack

The durability of an innovative self-healing micro-concrete in aggressive environments simulated by freeze-thaw cycles and salt spray test is studied. Tests are conducted on an ultra-high-strength reinforced micro-concrete that incorporates an autonomous self-healing mechanism based on the reaction of an epoxy compound enclosed within silica microcapsules and amine functionalised silica nanoparticles distributed within the cementitious matrix. The effect of aggressive environments is analysed in the self-healing micro-concrete and in a reference micro-concrete stored for 28 d in laboratory conditions after cracking, for crack widths of 150 and 300 μm. The results of capillary water absorption tests, complemented by electron microscopy analysis, confirm the enhanced durability of the autonomously self-healed material in both the freeze-thaw and the salt spray tests, as compared to the reference micro-concrete. In conclusion, the innovative self-healing mechanism is expected to increase the service life of structures in humid, cold climates and chloride-containing environments.