Hysteretic behavior of rapid self-sealing of cracks in cementitious materials incorporating superabsorbent polymers

In this study, the hysteresis in the swelling behavior of spherical superabsorbent polymers (SAPs) on rapid self-sealing of cracks in cementitious materials under wet/dry cycles was evaluated experimentally. The results from an experiment using the tea-bag method showed that the absorption capacity of SAPs was lower in a cement pore solution compared to that in distilled water. As the SAP particles repeatedly swelled/deswelled, their absorption capacity increased until 3–cycle and then gradually decreased. The water-flow test results showed that the mean reduction ratios in water runoff through cracks for the cracked specimens containing spherical SAP particles were 0.278 and 0.367 for SAP dosages of 0.5% and 1.0% in 1–cycle, respectively. As the wet/dry cycles were repeated, however, the ratios gradually increased and converged to about 1.75 times and 1.99 times those of 1–cycle, respectively. A non-linear regression analysis was performed on the measured reduction ratios in flow rates per cycle. The modification factors for the volume fraction of a crack sealed by the swollen spherical SAP particles gradually increased and then converged with the repeated wet/dry cycles, and they were approximately 1.0259–1.0599 and 1.0657–1.0943 for the S–0.5 and S–1.0 specimens after 4–cycle, respectively. In conclusion, the experimental results indicated that SAPs can repeatedly exhibit rapid crack self-sealing performance in cementitious materials.