Rapid determination of critical chloride content in cement-based composites

The critical chloride content (C_crit) is a necessary parameter for estimating the time-to-corrosion initiation in reinforced concrete structural elements exposed to chloride ions. However, the experiments that are typically used to determine C_crit in real concrete specimens are extremely time-consuming (several months or years) due to the slow diffusion of chloride ions through concrete. A new experimental method, called Rapid Corrosion Initiation (RCI), for fast estimation of C_crit is proposed in this article. This method employs an electric field inside small-scale reinforced concrete beam specimens to accelerate the chloride ion migration through concrete. The macro-cell current technique is used to monitor the corrosion activity. The acid-soluble chloride content at the reinforcement-concrete interface is measured using silver-nitrate titration. The estimated C_crit range using the RCI method is in good agreement with that reported in the literature using conventional methods. The C_crit for initiating corrosion of reinforcement embedded in a Strain Hardening Cementitious Composite (SHCC) matrix is also determined in this study using the RCI method.