Implementation of self-healing in concrete – Proof of concept

Triggered by newly formed defects (such as cracks) in the host materials, self-healing systems have the ability to effect healing automatically and thereby delay or prevent subsequent damage. Self-healing materials have been conceptualised and researched upon in recent years but the difficulty in implementation has delayed its prevalent usage. One difficult medium in which self-healing systems has yet to be implemented widely in practice is concrete. The casting of concrete causes vibration and impact of aggregates on the self-healing system and the subsequent curing causes shrinkage and thermal stresses. In this article, the selection of the healing agent and its containment and the effectiveness of a self-healing system in concrete medium are addressed. Through the use of glass tubes (with inner and outer diameters of 4 mm and 6 mm respectively) that are filled with one-part epoxy and embedded in steel-mesh-reinforced mortar specimens, it is found that repeated autonomic healing can be achieved with an increase in strength of approximately 30% over the initial value. For protection against premature breakage, it is necessary to wrap a 6.5 mm layer of mortar around the glass tube and cure for one day before casting the main beam.