Experimental investigation of the electro-chemical characteristics of SFRCs under the effect of chloride ion intrusion

Steel fiber-reinforced concrete (SFRC) has been recognized for its excellent durability in severe corrosive environments and its ability to improve the mechanical performance of concrete. However, the anti-corrosion mechanisms of steel fibers towards the embedded rebar have not been clarified, and a design that reflects the inherent electro-chemo-mechanical performance of SFRC has yet to be established. To understand the electro-chemical properties, accelerated corrosion tests induced by chloride penetration were conducted in this study using transparent porous materials with embedded steel fibers and rebars, which enabled visualization of the whole polarization areas. The experimental results indicate that steel fibers delay onset of rebar corrosion and inhibit subsequent corrosion progression. Mechanisms of anti-corrosion owing to fibers are explained as: (1) When a difference in chloride ion concentration arises between surface layers and the interior, the anodic reaction gets dominant in the surface layer, but meanwhile, the cathodic reaction dominates inside where reinforcing bars are located, and: (2) A corrosion protection system appears when dispersed steel fibers affects the rate of corrosion current around the rebars. Consequently, a rebar macro-cell circuit would be hardly formed. • An experiment of SFRC corrosion with pseudo concrete. • Macro-cell corrosion induced by chloride ion penetration. • Observation and measurement of electro-chemical properties. • Mechanism of anti-corrosion effect of fibers towards rebar.