Assessment of steel fiber corrosion in self-healed ultra-high-performance fiber-reinforced concrete and its effect on tensile performance

This study evaluated steel fiber corrosion and tensile behaviors of plain and self-healed ultra-high-performance fiber-reinforced concrete (UHPFRC) exposed to 3.5% sodium chloride (NaCl) solution. The degree of steel fiber corrosion was quantitatively evaluated via energy dispersive X-ray spectroscopy (EDS) and atomic force microscopy (AFM) image analyses. Test results indicate that, even after a 20-week immersion in the NaCl solution, only few steel fibers located near the surface of the non-cracked UHPFRC samples were slightly corroded, and they insignificantly affected the tensile behavior. A slightly better tensile performance was achieved by self-healing process, and it was further improved after exposure to the NaCl solution for a longer duration due to the moderately corroded steel fibers through the partially self-healed cracks. The surface roughness of the pulled-out steel fibers from the composites increased due to the self-healing and corrosion processes, relevant to the enhanced tensile performance, and by increasing the immersion duration.