Durability of cracked SFRC exposed to wet-dry cycles of chlorides and carbon dioxide – Multiscale deterioration phenomena

This paper describes an experimental study that comprised the exposure of cracked SFRC members to wet-dry cycles involving chloride and carbon-dioxide for two years. Results indicate that corrosion of steel fibres occurs mainly at the outer regions of the crack for cracks smaller than 0.3 mm, where the pH inside the crack drops below values of nine. The presence of chloride affected mainly the extent of corrosion. The results indicate that corrosion damage of the steel fibres does not necessarily play a dominant role on the overall deterioration of the composite; since changes in the microstructure of the matrix surrounding the crack and the fibre-matrix interface due to leaching and autogenous healing, may have a substantial impact on the long-term behaviour of the cracked composite. A conceptual deterioration model was developed, describing the deterioration and recovery mechanisms that alter the long-term mechanical performance of the cracked composite under wetting-drying conditions.