Chloride Transport Characterisation in Self-healing Concretes

It is essential to evaluate the deterioration of concrete structures in a chloride-laden aggressive environment, which may lead to the corrosion of embedded reinforcement and eventually to the loss of the integrity of the concrete structure. Several tests are available in the literature that evaluates the ingress of deleterious chemical species into the concrete matrix, but an uncracked state of concrete is largely considered in these tests. This work demonstrates the testing of concrete samples from full-scale beam elements, the introduction of cracking imitating the realistic crack specifications, and analysis for service life evaluation for cracked concretes. The autogenous property of crack healing in concrete is amplified by the addition of self-healing agents - crystalline admixture and bacteria. This study highlights that the presence of cracks in concrete significantly influences the chloride ingress profile. Two-fold diffusion of ions occurs - one perpendicular to the exposed surface and the other perpendicular to the crack walls. It is reported that the cracked and uncracked migration coefficients through and across the crack are highly affected by its existence, not necessarily controlled by the crack width at the surface. Consequently, the service life evaluation for a cracked concrete element needs to be adapted to account for the influence due to cracking.