Evaluation of self-healing in cementitious materials with superabsorbent polymers through ultrasonic mapping

The maintenance and repair of concrete infrastructure covers an increasing portion of the annual construction budget. For this reason, self-healing cementitious materials have been investigated thoroughly in literature. One way to achieve an effective self-healing composite is by promoting their inherent repair ability through the inclusion of superabsorbent polymers (SAPs). Thanks to their large absorption capacity upon contact with water, SAPs allow to preserve the humidity inside the cracks for a longer period of time, which is essential to promote the autogenous healing process. In order to encourage the application of SAPs for self-healing purposes, adequate assessment techniques should be at hand in order to evaluate a SAP's effectiveness for self-repair. Whereas various methods, such as water permeability tests and microscopic analysis, are used to assess a material's self-healing potential, mechanical tests are needed to determine the regain in mechanical performance. Due to the destructive nature of these methods, the monitoring of the self-healing mechanism over time is practically impossible. In the present research, a non-destructive testing methodology based on ultrasonic wave through transmission was investigated, due to its sensitivity to the elastic properties of the material under study. By means of ultrasonic mapping, the interior was visualized and allowed to determine the degree and uniformity of healing along the depth for different healing times for the first time in literature.