Chloride penetration resistance in sound and micro-cracked concretes through different experimental techniques

Concrete resistance to chloride penetration is one of the main design parameters for the assessment of reinforced concrete structures durability in chloride-contaminated environments, and it is usually determined through one of the accredited accelerated tests in uncracked configuration. In this study, the resistance to chloride penetration was evaluated on six different concrete types, in uncracked and load-induced micro-cracked configurations, subject to pure diffusion and considering two different analysis techniques, colorimetric and potentiometric titration. Results showed that in uncracked conditions, good correlation subsisted between the diffusion coefficients evaluated through the two techniques. In cracked configuration (micro-cracks 10-75 µm wide and 5-45 mm deep) with both techniques a significant increase in chloride diffusion coefficient was detected for concretes with lower w/c ratio, suggesting that the effect of cracks may be more pronounced for more impervious concretes.