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

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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: Special Publication

Volume: 312

Issue:

Appears on pages(s): 1-12

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

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.