Effect of Protein Containing Hydrogels on the Self-Healing of Cementitious Materials

This study examined the effect of hydrogels containing urease and proteins on the self-healing of cracked cementitious materials. The encapsulation of proteins and urease decreased the absorption of hydrogels. It was shown that proteins were able to release from hydrogels into the surrounding cementitious matrix. TGA, FTIR, and SEM showed increased calcium carbonate formation, and optical imaging indicated enhanced crack filling in the samples with hydrogels containing urease and proteins, compared to the control sample. This is attributed to the enhanced autogenous healing provided by water absorption/desorption of hydrogels as well as enzymatic reaction. Calcite was shown to be the dominant polymorph of calcium carbonate in the healing products. Interestingly, the mechanical strength regain was markedly higher in the samples with hydrogels containing urease and proteins compared to the control sample. Improved interfacial strength at the microstructure level enhances cohesion within healing products and adhesion between the healing products and crack surface, leading to overall increased mechanical strength regain. The electrical resistivity results were shown to be in agreement with the mechanical strength regain.