Evaluation of crack self-sealing in flexural concrete members with SAPs by chloride ion penetration resistance

Self-sealing concrete is a technology to repair cracks using swelling properties of superabsorbent polymers (SAPs) without external work. Many studies have been conducted on SAPs as selfsealing materials that fill cracks in concrete. However, because each study evaluated self-sealing performance using different experimental methods, each study reported different results. Therefore, a standardized test method to evaluate the self-sealing performance of SAPs is needed. This study evaluated the self-sealing performance of cementitious materials with SAPs through water absorption, chloride ion penetration, and water flow tests and analyzed the correlations between the results. Two SAPs with different particle sizes were used, and their contents were set to 0.3%, 0.5%, and 0.7% depending on the binder weight. The experimental results revealed that the selfsealing performance improved with increasing particle size and SAP content. In the water absorption test, the amount of water absorbed by the surface of the original specimen and that absorbed through cracks were measured. However, the influence of the self-sealing ability of the SAPs on the total water absorption rate could not be clarified. A chloride ion penetration test was conducted to measure the chloride ion penetration depth directly, and the corresponding results indicated that the self-healing ability of the SAPs enhanced the resistance of the cementitious materials against the penetration of harmful ions. Finally, a water flow test was performed, and the results revealed that the short-term self-sealing performance of SAPs can be evaluated relatively independently.