The impacts of silane functionalized hydrogels on early-age nucleation and growth of cement hydrates

Composite alkoxysilane-crosslinked polymer hydrogels were synthesized and investigated for their ability to react with cementitious mixtures and affect the morphology and growth of cement hydrates. Hydrogels were characterized through FTIR, gravimetric swelling tests, and scanning electron microscopy as synthesized and in cementitious environments such as pore fluid and cement paste. The impact of the composite gels on overall cement hydration was analyzed through isothermal calorimetry. CryoSEM offered unique insights into early age hydrate formation and the interactions between hydrogels and fresh cement paste. Conventional hydrogels exhibited growth dominated hydrate formation at early ages and macrovoid formation at later ages in the cement paste. Silane containing gels showed the ability to dissolve in alkaline cementitious mixtures and diffuse into cement paste. Furthermore, the silane containing gels contributed to microstructural refinement by facilitating nucleation dominated hydrate growth and reduced the overall volume of hydrogel-related macrovoids in the cement matrix.