Author(s)

Andrea Hartmann¹, David Schulenberg², Josef-Christian Buhl¹

¹Institut für Mineralogie, LUH, Hannover, Germany.
²Institut für Baustoffe, Bauphysik und Bauchemie, TUHH, Hamburg, Germany.

Calcium-Silicate-Hydrate-phases (CSH-phases) are important binding agents of building materials. The synthesis of CSH phases and their structural characterization was done to investigate the crystallization in dependence of an increasing CaO/SiO₂ ratio (C/S ratios) from 0.41 up to 1.66 at temperatures in the crossover region of tobermorite to xonotlite (180℃ and 230℃). Parallel runs with the same C/S ratio but on the one hand with constant mass of quartz and variation of lime and on the other hand under reverse conditions (constant mass of lime but variable amounts of quartz) were performed at both temperatures. The aim was to clarify the connections of crystallization mechanism and kinetics of phase formation with structure, crystallinity and morphology of the CSH’s in the mentioned C/S ratio for both temperatures in the tobermorite-xonotlite crossover region. The parallel experiments with different mass ratios of the educts are important to study the influence of time evaluation of supersaturation within the solution under the peculiarities of the retrograde solubility of lime but accelerated solubility of quartz. The products were characterized by XRD, SEM/EDX, FTIR and ²⁹Si MAS NMR spectroscopy (using the Q-site nomenclature [1]). The experiments could clarify some important connections of crystallization process and the reaction pathway.

CSH-Phases, Tobermorite, Xonotlite, C/S Ratio, ²⁹Si MAS NMR Spectroscopy

Hartmann, A. , Schulenberg, D. and Buhl, J. (2015) Synthesis and Structural Characterization of CSH-Phases in the Range of C/S = 0.41 - 1.66 at Temperatures of the Tobermorite Xonotlite Crossover. Journal of Materials Science and Chemical Engineering, 3, 39-55. doi: 10.4236/msce.2015.311006.