Desorption of superabsorbent hydrogels with varied chemical compositions in cementitious materials

This paper examines the desorption of hydrogels synthesized with varied chemical compositions in cementitious materials. The absorption, chemical structure and mechanical response of hydrogels swollen in a cement mixture were studied. The effect of the capillary forces on the desorption of hydrogels was investigated in relation to the chemical composition of the hydrogels. In the second set of experiments, the behavior of the hydrogels in a hydrating cement paste was monitored by tracking the size and morphology evolution of hydrogels interacting with the cement paste matrix. It was shown that the changes on the surface characteristics of hydrogels as a result of interactions with the pore solution and cement particles can affect the desorption rate of hydrogels in contact with porous cementitious materials. Scanning electron microscopic examination demonstrated two different desorption modes with distinct morphologies of hydrogels depending on the chemical composition of hydrogels. The effect of the interfacial bonding between the hydrogels and the cementitious matrix and its relation to the desorption is illustrated.