The Change of Silica Tetrahedron in Cement-Silica Fume Blends Hydration

Abstract:

The change of silica tetrahedron in cement-silica fume blends hydration is critical for blended cement application. ²⁹Si solid-state magic angle spinning nuclear magnetic resonance (MAS NMR) investigations on the change of silica tetrahedron, which were Portland cement hydration, silica fume in simulated hydration and cement-silica fume blends hydration, were characterized and compared in this paper. The experimental results revealed that the amorphous silica tetrahedron structure in silica fume changed into Q¹ and Q² silica tetrahedrons, the same as silica-oxide structure of cohesive gel in the hydration of Portland cement. The coexistence of Q¹ and Q² silica tetrahedron in hydration product was beneficial to the strength increase of blend paste with silica fume. The amount of Q² silica tetrahedron in cement-silica fume blends was higher than that in Portland cement. The pozzolanic reaction of silica fume accelerated the course of the silica tetrahedron in blended paste turning into the stable state of Q² silica tetrahedron and existing principally in blended paste. That is reason that the physical properties of cement-silica fume blends are better than those of Portland cement.

• Periodical: Materials Science Forum (Volumes 743-744)
• Pages: 280-284
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.743-744.280
• Online since: January 2013
• Authors: Xiao Jun Wang, Xiao Yao Wang, Hong Fei Zhu, Xiao Ye Cong
• Keywords: Blended Cement, Nuclear Magnetic Resonance, Silica Fume (SF), Silica Tetrahedron

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