Cross-linkable polyethers as healing/sealing agents for self-healing of cementitious materials

To date, the potential of several types of polymeric materials as healing agents for self-healing of concrete has already been investigated. Generally, for self-healing concrete with encapsulated polymeric healing agents, the curing mechanism is triggered upon contact with moisture/air or upon reaction with a second component provided by additional capsules. The present work explores the use of in-situ curable hydrogels formed as a result of the elevated pH of the cementitious matrix, via a Michael-type addition reaction, as potential healing/sealing materials for concrete applications. For this purpose, a variety of acrylate-endcapped urethane-based precursors were synthesized and combined with a thiol-based cross-linker. Various properties including the viscosity, the curing time, the swelling capacity and the cross-linking efficiency have been evaluated. The potential of the developed materials to seal concrete cracks was assessed through manual injection. The results indicate that the cross-linking reaction can readily occur in-situ due to the alkaline environment of the cementitious matrix and that the hydrogels exhibit favorable sealing properties.