For indoor applications such as tunnels and warehouses, no. For outdoor applications such as pavements some minor rusting may occur. Experience in highways and industrial pavements indicate that while individual fibers corrode at the surface, staining of the concrete surface does not occur. Overall aesthetics and serviceability are maintained even with the presence of individual fiber corrosion. Indoor Applications-Surface fibers in typical indoor tunnels or manufacturing floor applications remain bright and shiny under normal environmental conditions.
Outdoor Applications Without cracks-experience has shown that concrete specified with a 28-day compressive strength over 3000 psi, mixed with standard water/cement ratios, and installed with methods that provide good compaction, limit the corrosion of fibers to the surface skin of the concrete. When surface fibers corrode, there is no propagation of the corrosion more than 0.008” beneath the surface. Since the fibers are short, discontinuous, and rarely touch each other, there is no continuous path for stray or induced currents between different areas of the concrete. Outdoor Applications With cracks-laboratory and field-testing of cracked SFRC in environments containing chlorides has indicated that the cracks in concrete can lead to corrosion of the fibers passing across the crack. However, small cracks (crack widths < 0.008”) do not allow corrosion of steel fibers passing across the crack. If the cracks wider than 0.008” and are limited in depth, the consequences of this localized corrosion are not structurally significant.