Healing of dynamic concrete cracks using acrylate-endcapped polymer precursors

The occurrence of cracks in concrete is inevitable due to its limited tensile strength. Up to now, several approaches have been used to design concrete with self-healing properties. Depending on the type of damage, different healing agents can be used. In case of dynamic cracks in structures exposed to cyclic loads, elastic healing materials can be used to cope with the crack opening and closing movement. In this study, we aimed at determining the most suitable polymer backbone to be applied for the healing of dynamic cracks. For this purpose, different polymeric precursors including siloxane- (PDMS), polypropylene glycol/urethane- (PPG), epoxy- and polyester-based (PE) have been evaluated. The healing capacity was evaluated by determining the regain in water tightness of the healed cracks using water flow tests. The strain capacity of the polymers was assessed after widening of the healed cracks in a stepwise fashion. Comparison of the sealing properties before and after each stepwise elongation shows that a strain of at least 50% could be achieved for epoxy and PDMS-based healing agents. For polyester and PPG-based precursors failure occurred due to polymer detachment. The effect of high alkalinity on the degradation of the polymerized healing agents has been also evaluated with the PPG-based precursor showing the best performance in terms of degradation. and PE the highest mass loss percentage after incubation in concrete pore solution