Direct characterization of steel fibre corrosion in pre-cracked ultra-high performance concrete (UHPC) with different crack widths

The potentiodynamic polarization was used to directly characterize steel fibre corrosion, and the voltammetry was used as the complement, in pre-cracked ultra-high performance concrete (UHPC), during 36 wetting-drying cycles lasted for 180 days. Cracks of 5 different widths of 0 mm, 0.25 mm, 0.50 mm, 0.75 mm and 1.00 mm were pre-produced in specimens. Results showed that steel fibre on the surface of concrete easily corroded and the effect of chloride ion on steel fibre corrosion in UHPC was mainly limited to the vicinity of crack. In this experiment, after 30 wetting-drying cycles in NaCl solution, the corrosion degree of steel fibers in UHPC with crack widths of 0.50 mm and 0.75 mm was lower than that with other widths.