Preliminary analysis of non-destructive test methods to evaluate the self-healing efficiency on the construction site

In the last decades major advances have been made in the development of self-healing concrete which is able to heal its own cracks without the need for traditional repair interventions, thereby increasing its durability and service life. Recently, more and more self-healing technologies have been applied in demonstrator projects. These demonstrator projects have made it evident that we need to develop new testing methodologies to evaluate the self-healing performance, as many laboratory test methods cannot be applied on structural elements on the construction site. In the current study different non-destructive test methods have been used to analyse the self-healing performance of concrete beams. These beams were cracked in a three-point bending setup. Part of the beams had a cast-in vascular network allowing the crack to be healed via the injection of polyurethane. The healed beams were compared to the reference beams without the vascular network by applying different test methods: microscopy, concrete moisture content, resistivity, air permeability, water permeability, and ultrasound. Based on the results of these methods which were obtained under laboratory conditions, it was found that the concrete moisture content and the resistivity only provided limited value in terms of conclusions for self-healing. All test methods were also applied to concrete walls on site. Based on this last measuring campaign, recommendations are provided for quantification of the self-healing efficiency on the construction site.