This study investigates the effect of early age curing on microstructural evolution of cement paste with nano-additives using advanced beamline techniques. Early age hydration dynamics of Portland cement paste with nano-silica and nano-alumina was examined using quasi-elastic neutron scattering (QENS), ultra small angle X-ray scattering (USAXS), small angle X-ray scattering (SAXS), and wide angle X-Ray scattering (WAXS). Cement mixes were made of Ordinary Portland Cement and up to 2.00% by dry weight of nano-additives. Up to 2.00% by dry weight of nano-additives were added to Ordinary Portland Cement.<br/><br/>QENS results showed that the concentration of the nano-silica influenced the bound water index and self-diffusion coefficients of hydration water confined in the pores of the cement matrix. Furthermore, the seeding effect leading to nucleation effect of gels was also observed during the course of hydration, providing an insight into the optimum dose of nano-silica. The evolving morphology during the course of hydration was examined by USAXS, SAXS, and WAXS. Scans were taken 2 hours, 7 days, and 56 days after batching. Addition of nano-alumina led to formation fractal disks of calcium alumino silicate hydrate (C-A-S-H) gel along with the densified calcium-silicate-hydrate (C-S-H) gel, whereas addition of nano-silica formed additional C-S-H. This work shows that the concentration of nano-silica had significant influence on the morphology and surface area during early stage of hydration. Advanced beamline characterization techniques were useful in providing providing an insight into the effect of additives on the hydration mechanism, including the early-stage initiation, dissolution, and gelation processes, as well as the subsequent polymerization and hardening processes.

Hydration dynamics and morphology of cement pastes with engineered nano additives studied via advanced beamline techniques

253rd National Meeting (2017)

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