Beaudoin – Nanostructural Metamorphosis and Engineering Behavior of C-S-H in Hydrating Cement Systems

R. Alizadeh, J. J. Beaudoin, and L. Raki

Institute for Research in Construction , National Research Council Canada

Hydration studies of C3S-synthetic C-S-H systems were conducted using quantitative 29Si MAS NMR.  Two types of C-S-H were identified – one that emanates from the surface of C3S grains and one that nucleates on the synthetic C-S-H particles. In addition to the accelerating effect of the C-S-H seeds (varying C/S ratio) the C-S-H product that forms on the synthetic C-S-H surfaces results in a nanostructural metamorphosis i.e. the nucleated C-S-H has a higher degree of polymerization than the C-S-H forming on C3S surfaces. The process is dependent on the C/S ratio of the synthetic C-S-H addition. A model for the growth and interaction of the nucleated C-S-H with the seeds is presented. Data obtained from DTA , SEM and Isothermal Calorimetry are used to support conclusions based on NMR results. Discussion of tailoring C-S-H formation in cement-based materials is presented.  DMA results for synthetic  C-S-H support  arguments for the layered nature of C-S-H in hydrated Portland cement and are central to strategies pertaining to the tailoring of C-S-H formation for the enhancement of engineering performance.




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