Synthesis and Characterization of Polymer-Silica Composite Hydrogel Particles and Influence of Hydrogel Composition on Cement Paste Microstructure
| Autor: | Kendra A. Erk, Matthew J. Krafcik, Baishakhi Bose |
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| Rok vydání: | 2018 |
| Předmět: |
Materials science
Polymers and Plastics microstructure 0211 other engineering and technologies 02 engineering and technology macromolecular substances complex mixtures chemistry.chemical_compound Materials Science and Engineering 021105 building & construction Materials Chemistry Calcium silicate hydrate Hydrogel particles internal curing Curing (chemistry) Civil and Structural Engineering Acrylic acid Cement chemistry.chemical_classification Metals and Alloys technology industry and agriculture Polymer nanosilica 021001 nanoscience & nanotechnology superabsorbent polymer high-performance concrete Superabsorbent polymer Chemical engineering chemistry Mechanics of Materials Ceramics and Composites Pozzolanic reaction Cementitious 0210 nano-technology chemical admixtures |
| Zdroj: | School of Materials Engineering Faculty Publications |
| Popis: | The objective of this research is to define the fundamental structure-property relationships of water-swollen polymer hydrogel particles that are employed as internal curing agents in cementitious mixtures, in addition to reporting a novel synthesis procedure for combining pozzolanic materials with hydrogel particles. Solution polymerization was performed to incorporate amorphous nanosilica particles within acrylic-based polymer hydrogel particles of varying chemical compositions (i.e., monomer ratio of acrylic acid (AA) to acrylamide (AM)). Experiments were designed to measure the absorption capacity and kinetics of hydrogel particles immersed in pure water and cementitious pore solution, as well as determine the impact of particles on cement paste microstructure. While majority-AM hydrogel particles displayed relatively stable absorption values during immersion in pore solution, majority-AA hydrogel particles desorbed fluid over time, most likely due to the interactions of multivalent cations in the absorbed solution with the anionic polymer network. Interestingly, the addition of negatively charged nanosilica particles accelerated and enhanced this desorption response. When incorporated into cement paste, majority-AM hydrogel particles encouraged the formation of calcium hydroxide and calcium silicate hydrate within the void space previously occupied by the swollen particles. When nanosilica was added to the hydrogel particles, a 53 % increase in the number of hydrogel voids containing hydrated product was observed for the 17 % AA hydrogel particles, and a 140 % increase was observed for the 83 % AA hydrogel particles. These results suggest that the combination of nanosilica with polymeric hydrogel particles provides a favorable environment for the pozzolanic reaction to proceed and that nanosilica aids in the replenishment of hydrogel void space with hydrated cement phases. |
| Databáze: | OpenAIRE |
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