Self-repair of thermal cracks in concrete sandwich panels

Although the use of insulated concrete sandwich panels results in more energy-efficient buildings, the presence of this insulation layer can induce thermal cracks. As cracks form a preferential path for aggressive agents to enter and degrade the concrete matrix, and as they are not wanted in this application from an aesthetical point of view, they need to be treated. The aim of this study was to seal the cracks in concrete sandwich panels invisibly in an autonomous way. Therefore, the efficiency of various encapsulated healing agents was compared by inducing thermal cracks in concrete sandwich panels, thus causing capsule breakage and the release of the agents into the cracks. It was shown that encapsulation of both polyurethane and a water-repellent agent can result in a reduction in the water uptake by cracks. However, only when a water-repellent agent was released cracks were healed in an almost invisible way. This study has shown that the self-healing approach involving encapsulated polymer-based healing agents can also be applied to concrete sandwich panels, although more research will be needed to meet the specific healing requirements of this application.