Self-healing of Fibre Reinforced Concrete Containing an Expansive Agent in Different Exposure Conditions

While most studies about self-healing concrete investigated several healing conditions such as water immersion, humid chamber and wet/dry cycles, very few assessed the self-healing capacity of concrete in realistic outdoor condition. Furthermore, self-healing capacity is usually determined with a single testing procedure (mechanical or permeability measurements), sometimes with visual observations. Hence, this project aimed to evaluate, through mechanical and water permeability tests, as well as optical and microscopic observations on the same specimens, the self-healing capacity of high performances fibre reinforced concretes (HPFRC) containing different admixtures. This paper focuses on the water permeability evolution of two HPFRC (water to binder ratio of 0.43 and 0.75%-vol of steel macrofibres), one control and one containing calcium sulfoaluminate-based expansive agent (CSA), under different laboratory and outdoor conditions. Prisms were pre-cracked at 28 days by means of a 3-point bending test and then exposed to laboratory conditions (air, water immersion and wet/dry cycles) for 3 months and outside for one year. The results showed a better self-healing performance of the CSA HPFRC in wet/dry cycles compared to water condition. For the control HPFRC, the opposite is observed. Self-healing of outdoor prisms is slower than in laboratory (6 months outside corresponds to around 2 weeks in water immersion for CSA). Self-healing performance of the CSA HPFRC is better than the control mix in outdoor condition.