A Novel Method of Self-Healing in Cementitious Materials by Using Polyacrylic Hydrogel

Cementitious materials are the most widely used in the construction. However, cementitious materials have defects such as low tensile strength which is easy to cause the formation of cracks. In recent years, with the research and application of smart materials, intelligent cementitious materials with self-sensing, self-diagnosis and self-healing functions have received extensive researcher’s attention. In this paper, a polyacrylic hydrogel that could be utilized for self-healing of cementitious materials was designed, and the three-dimensional network structure of the hydrogel controlled the release rate of encapsulated repair agent. The phosphate-incorporated hydrogel was filled into cement slurry to prepare self-healing cementitious materials. After the cement sample cracked and water penetrated into the crack, the phosphate was released from hydrogel. Phosphate reacted with the calcium in the pore solution to form hydroxyapatite type minerals which healed the crack. The self-healing cementitious material is in a position to heal cracks of 300 μm in width. After healing for 28 days at 20oC and 95% of RH, the compressive strength of precracked specimens could reach 85% of that of intact ones.