The behavior of poly(sodium acrylate-co-acrylamide) copolymer hydrogels with varied chemical compositions in artificial pore solutions with three different pH values is examined. The absorption, chemical characteristics, mechanical stiffness, and desorption of the hydrogels in contact with a porous cementitious material were investigated. It was observed that the surface characteristics of the hydrogels play an important role in the desorption of hydrogels due to the capillary forces. It was shown that in the hydrogel systems studied here, the bonding between the hydrogels and the porous cementitious material is improved with an increase in the content of acrylamide in the hydrogels, and this results in an increased desorption rate of the hydrogels.

The effect of hydrogels containing nanosilica (NSi) on the autogenous shrinkage, mechanical strength, and electrical resistivity of cement pastes was studied. The interaction between the hydrogels and the surrounding cementitious matrix was examined using thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The addition of hydrogels decreased autogenous shrinkage in the cement pastes and this reduction showed a dependence on the concentration of NSi in the hydrogels. Compressive strength and electrical resistivity were reduced in the cement pastes with hydrogels and this reduction was decreased with increased concentration of NSi in the hydrogel. A change in the phase composition of the cement paste in the region close to the hydrogel was noted, compared to the region away from the hydrogel. In a lime solution with increased pH and temperature, Ca(OH)₂ and CaCO₃ were found to form within the hydrogels; evidence of calcium-silicate-hydrate (C-S-H) formation in the hydrogels with NSi was obtained, indicating the possible pozzolanic potential of the hydrogels with NSi.