Monitoring of self-healing within cementitious materials including superabsorbent polymers by means of elastic waves.

The inclusion of superabsorbent polymers to cementitious materials
enables the improvement of the self-healing ability through a more
continuous water supply. Using surface ultrasonic measurements, the
closure of cracks was monitored over time and could be correlated to
microscopic analysis, but no information regarding healing at different
depths is available. Also, the link with the regain in mechanical
performance, being the ultimate goal of a self-healing material,
should still be assessed. The sensitivity of ultrasound waves to the
elastic properties of materials suggests a quantification of the
stiffness of formed healing products, which allows to predict the
healing capacity in a non-destructive way. Additionally, ultrasonic
tomography will provide more information on the location of
effectively healed zones inside the crack by means of scanning the
entire surface. Lastly, the establishment of a contactless ultrasound
set-up will facilitate the measurements, allow for in-situ monitoring of
the self-healing mechanism and introduce the possibility of
automated evaluation.