Investigating the effect of hydrogel characteristics on the self-healing of cementitious materials

Despite prior studies investigating the self-healing of cementitious materials containing hydrogels, the dependence of self-healing on the properties of hydrogels has not been sufficiently explored and is poorly understood. Thus, the novelty of this paper is to examine the self-healing of cementitious materials containing multiple hydrogels with different behaviors. Thermogravimetric analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy equipped with energy dispersive x-ray spectroscopy were employed to probe the chemical characteristics of the healing products. The three-point bend test and optical microscopy were used to evaluate the mechanical strength recovery and crack filling, respectively, in the cementitious materials containing hydrogels. The healing products were shown to comprise calcium-silicate-hydrate (C-S-H), ettringite, calcium hydroxide, and calcium carbonate. The hydrogel modified paste with the highest water sorption demonstrated the highest calcium carbonate content. All hydrogel modified pastes exhibited improved strength recovery and crack filling compared to the control paste and this improvement was more pronounced in the paste with the highest water sorption.