Ion-responsive self-healing concrete with sensing capability for enhanced sulfate resistance

To address the deterioration of concrete structures caused by severe sulfate corrosion in western regions, which leads to reduced durability and safety, a self-sensing and self-healing anti-corrosion microcapsule with sulfate ion responsiveness was designed using polyacrylamide (PAM) as the core material and ionic liquids (ILs) as the shell material. The optimal stirring temperature and duration for microcapsule preparation were determined based on measurements of particle size distribution, ion-responsive behavior, and encapsulation efficiency. The microcapsules were incorporated into concrete at dosages of 1 %, 2 %, and 3 % of the cementitious material, and their effects on dynamic elastic modulus, pore structure, and sulfate ion concentration were examined. The mechanism was elucidated, and the sulfate corrosion rate of concrete after 480 days of indoor exposure was evaluated. The results indicate that when the stirring temperature is maintained at 70 °C and the stirring duration is 24 h, the microcapsules exhibit a uniform particle size distribution and the highest encapsulation efficiency. However, the temperature has minimal influence on the ion-responsive rate. The incorporation of microcapsules reduced the early-stage dynamic elastic modulus of concrete but significantly improved it at later stages compared to the control group. Based on the variation in relative dynamic elastic modulus, the sulfate corrosion process of concrete was divided into a performance enhancement phase, a degradation phase, and a deterioration phase, with the degradation and deterioration phases significantly delayed by the incorporation of self-sensing and self-healing microcapsules. The addition of microcapsules significantly reduced the proportion of harmful and more harmful pores, decreased the sulfate ion penetration depth, and enhanced the corrosion resistance of concrete. The findings provide a novel solution for enhancing sulfate corrosion resistance in concrete exposed to saline soil environments in western regions.