Smart superabsorbent polymers for self-sealing and -healing of mortar

ID No: 54 Abstract: Concrete is an important building material, due to its ease to use and relatively low cost. However, the presence of cracks endangers the durability of concrete and can result in reinforcement corrosion since a pathway for harmful particles dissolved in fluids and gases is generated. Manual repair costs can go up to half of the annual construction budget. Instead, introducing a superabsorbent polymer (SAP) during concrete mixing can create a self-sealing and -healing material. Some SAPs undergo major characteristic changes by small environmental variations. These so-called ‘smart’ polymers have the ability to sense environmental stimuli. The use of pH-responsive SAPs can be extremely useful for the envisaged application (i.e. selfsealing and self-healing of cracks). When cracks in concrete are subjected to external wetting, ingress of moisture will cause the SAP to swell. When the external fluid possesses a low ionic strength, the SAP will swell to such an extent that it completely fills the crack and slow down or even prevent the further infiltration of water. In addition, these polymers may promote autogenous healing. The proposed paper discusses the self-sealing and -healing effect of two pH-responsive SAPs. First, the SAPs have been characterized completely. They are inserted in mortar (a varying amount of SAPs expressed as SAP/C: dosage of superabsorbent polymer by weight per mass unit of cement 0.005 and 0.01). The sealing efficiency has been measured through a water permeability set-up. The results indicate that a higher fraction of SAP leads to a stronger self-sealing. Interestingly, the formation of the healing products is found at the bottom of the cracks after the water permeability measurements, indicating the self-healing effect of these SAPs. These newly developed polymers are thus promising for the targeted application. Concrete is an important building material, due to its ease to use and relatively low cost. However, the presence of cracks endangers the durability of concrete and can result in reinforcement corrosion since a pathway for harmful particles dissolved in fluids and gases is generated. Manual repair costs can go up to half of the annual construction budget. Instead, introducing a superabsorbent polymer (SAP) during concrete mixing can create a self-sealing and -healing material. Some SAPs undergo major characteristic changes by small environmental variations. These so-called ‘smart’ polymers have the ability to sense environmental stimuli. The use of pH-responsive SAPs can be extremely useful for the envisaged application (i.e. selfsealing and self-healing of cracks). When cracks in concrete are subjected to external wetting, ingress of moisture will cause the SAP to swell. When the external fluid possesses a low ionic strength, the SAP will swell to such an extent that it completely fills the crack and slow down or even prevent the further infiltration of water. In addition, these polymers may promote autogenous healing. The proposed paper discusses the self-sealing and -healing effect of two pH-responsive SAPs. First, the SAPs have been characterized completely. They are inserted in mortar (a varying amount of SAPs expressed as SAP/C: dosage of superabsorbent polymer by weight per mass unit of cement 0.005 and 0.01). The sealing efficiency has been measured through a water permeability set-up. The results indicate that a higher fraction of SAP leads to a stronger self-sealing. Interestingly, the formation of the healing products is found at the bottom of the cracks after the water permeability measurements, indicating the self-healing effect of these SAPs. These newly developed polymers are thus promising for the targeted application.