Comprehensive evaluation of self-healing of concrete with different admixtures under laboratory and long-term outdoor expositions

This project presents the evaluation of the self-healing of fibre reinforced concretes containing various admixtures (crystalline admixture CA, expansive agent CSA, superabsorbent polymer SAP) and combinations. They were exposed to several laboratory conditions (water immersion, wet/dry cycles ambient air for 3 months, water flow for 1 week) and to a long-term outdoor exposure for 1 year. Self-healing capacity was assessed by water permeability measurements, mechanical recovery, visual observations and microscopic analyses on the same specimen. This paper presents the mechanical behaviour and microstructure of the healing products, and the correlations with the water permeability measures presented in previous research. The results showed that a high healing of cracks based on water permeability did not necessarily lead to a high mechanical recovery. The highest Strength Regains (109% in average) were obtained for specimens exposed outdoor that presented the lowest Healing Ratios (71% in average). The local density of the healing products may govern the Healing Ratio, while the type of healing products and their extent in the crack depth may control the Strength Regain. Finally, the SAP mix showed overall the best self-healing performance, regarding both durability and mechanical properties.