Hydrogels can be used to internally cure concrete which has been shown to increase the growth of hydration products and therefore increase strength. This concrete is also more environmentally viable as more durable concretes reduce need for future production. Crosslinked polyacrylamide (PAM) hydrogels produced by inverse suspension polymerization have previously seen success in concrete strengthening. This polymerization method involves the suspension of PAM components in water droplets in a continuous organic solvent phase. A major benefit of this polymerization technique is particle size control, which can be difficult in bulk samples prepared in solution polymerization where the size distribution is often large. Size control and uniformity are useful for controlling water release properties and limiting the size of potentially weakening void spaces. The incorporation of silica into PAM has been shown to increase the presence of calcium-silicate-hydrate (CSH) which is a major hydration product and strengthening agent of concrete. This has previously been attempted with silica nanoparticles which did show increased CSH growth. However, silica was only found on the surface of hydrogel particles and caused instability issues in inverse suspension polymerization. Instead, a silane-containing molecule, 3-(Trimethoxysilyl)propyl methacrylate (TPM), was incorporated into the PAM matrix which acted as a crosslinker incorporating silica. This method of integration leads to higher uniformity and creation of potential nucleation sites for the formation of CSH. PAM-TPM was synthesized in both solution and inverse suspension polymerization. FTIR on hydrogel samples showed a characteristic Si-O peak indicating successful TPM integration. Additionally, PAM-TPM integrated concrete was compression tested and microstructural analysis was performed to analyze hydration product growth. Results from these experiments will be presented and analyzed to evaluate the effectiveness of PAM-TPM for the internal curing of concrete and promotion of CSH growth.

Inverse suspension polymerization of poly{acrylamide-co-[3-(Trimethoxysilyl)propyl methacrylate]} hydrogels for internal curing of cement

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