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Title: Correlating Microstructural Features, Elastic, and Viscoelastic Characteristics of Synthetic C-S-H

Author(s): S. H. Aboubakr, M. L. Begaye, E. Soliman and M. M. Reda Taha

Publication: Symposium Paper

Volume: 312

Issue:

Appears on pages(s): 1-12

Keywords: C-S-H, Nanoindentation, Density, Creep.

DOI: 10.14359/51689372

Date: 10/1/2016

Abstract:
In this study we report on characterization of synthetic calcium silicate hydrate (C-S-H) produced at relatively low Cao to SiO₂ (C/S) mixture ratio of 0.7 compared with C-S-H produced at 1.5 C/S mixture ratio. Synthetic C-S-H slurry was produced by mixing calcium oxide (CaO) to micro-silica (SiO₂) with large amount of deionized water. The slurry was then dried to the standard 11% relative humidity to produce a powder C-S-H. The C-S-H powder was then compacted at compaction pressures of 300 (43.5) and 400 MPa (58.0 ksi) to produce solid C-S-H discs. Modulus-density scaling relationships of C-S-H synthesized at 0.7 and 1.5 C/S ratios were established and compared. Microstructural characterization of C-S-H including Brunauer-Emmett Teller (BET) N₂, thermogravimetric analysis (TGA), and ²⁹Si magic angle spinning (MAS) nuclear magnetic resonance (NMR) were performed. We show that porosity, water content, and silicate polymerization affected the elastic and viscoelastic properties of synthetic C-S-H. We also show that elastic and viscoelastic properties of C-S-H synthesized at 0.7 C/S ratio are more sensitive to porosity than those of C-S-H synthesized at 1.5 C/S ratio.