Multi-scale characterization of the self-healing behavior of long-term cement-based materials with superabsorbent polymers

This research investigates the effect of particle size and content of superabsorbent polymer (SAP) on the self-healing performance of long-term cement-based materials. Crack closure and transport properties were evaluated after curing in saturated calcium hydroxide (CH) solution and deionized water (DW). The microscopic observation, capillary water absorption, and water seepage tests were used to evaluate the self-healing behavior, while scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and thermogravimetric (TG) analysis characterized self-healing products. The results show that the addition of SAP improves the crack healing effect of mortar after curing 300 d. SAP mortar with larger particle size and 1.0% SAP content showed better self-healing performance than smaller particle size and 0.5% SAP. Self-healing was more effective in saturated CH solution than in DW. More calcium carbonate was found on the surface of SAP mortar compared to the control group. This study aims to provide a basis for the long-term application of SAP in cement-based materials.