Perpendicular-to-crack chloride ingress in cracked and autonomously healed concrete

Abstract

Cracks in reinforced concrete structures exposed to a marine environment or de-icing salts can cause major durability issues due do accelerated ingress of chloride ions. In this study, the influence of autonomous crack healing by means of encapsulated polyurethane on the chloride ingress perpendicular to cracks was evaluated. This was done quantitatively by determining perpendicular-to-crack chloride profiles by means of profile grinding followed by potentiometric titration and qualitatively through visualization of the chloride penetration front by means of the AgNO3 spray method. The resulting chloride profiles showed that the healing mechanism was able to reduce the chloride concentrations in the direct vicinity of the crack to a large extent and to reduce the perpendicular-to-crack chloride penetration, especially further away from the exposed surface. Visualization of the chloride penetration front showed some variation in crack healing. For some healed samples almost no additional chloride ingress was found compared to uncracked samples, others showed a slightly enhanced ingress at the crack location but less perpendicular-to-crack chloride penetration compared to untreated cracked samples. Generally, the reduced amount of chlorides present in the concrete matrix due to crack healing will enhance the durability and service life of concrete structures.

Critical Aspects in the Development and Integration of Encapsulated Healing Agents in Cement and Concrete

“…Generally, when tubular macrocapsules are used, in most cases, the cement paste is prepared according to the standard procedure and the capsules are placed in a specific point of the mould/specimen during casting (Hu et al 2018;Van Belleghem et al 2018aTsangouri et al 2019;Anglani et al 2020b;Lv et al 2020a). A simple procedure for the calculation of the survivability ratio of macrocapsules has been proposed (Hilloulin et al 2015;Choi et al 2017a).…”