Modeling rapid self-sealing of cracks in cementitious materials using superabsorbent polymers

The aim of the study involves quantitatively evaluating rapid self-sealing of cracks in cementitious materials incorporating superabsorbent polymers (SAPs). To this end, the study proposes a model to predict changes in the amount of water runoff through cracks over time when spherical SAPs in cementitious materials exhibit rapid swelling by absorbing the first water ingress after the occurrence of cracks. X-ray computed tomography analysis demonstrates that the swelling of SAPs in the cracks of the specimens by distilled water was less than that in a free state. The water flow test results indicate that the ratio of water runoff over time decreases sharply in SAP-added specimens immediately after the commencement of the water flow test. Additionally, the reduction ratio of the flow rate for the specimens with a crack width range of 0.24–0.36 mm corresponds to 0.343–0.519, 0.524–0.716, and 0.631–0.826 in specimens S-0.5, S-1.0, and S-1.5, respectively. A nonlinear regression analysis was performed on the results of the water flow test, and this reveals that the modification factor for the volume fraction of cracks sealed by the swelling of spherical SAPs corresponds to 0.7056, 0.6642, and 0.6574 for SAP 0.5%, SAP 1.0%, and SAP 1.5%, respectively.