The Investigation of Nano Silica in the Cement Hydration Process

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Title: The Investigation of Nano Silica in the Cement Hydration Process

Author(s): J. Belkowitz and D.L. Armentrout

Publication: Special Publication

Volume: 267

Issue:

Appears on pages(s): 87-100

Keywords: calorimetry; cement hydration; compressive strength; nano-silica; scanning electron microscopy; x-ray diffraction.

Date: 10/1/2009

Abstract:
With the advent of nano technology, materials have been developed that can be applied to high performance concrete mix designs. Nano silica reacts with calcium hydroxide to develop more of the strength carrying structure of cement paste, calcium silica hydrate. In this paper, predictive relationships have been developed to distinguish the strength benefits when using different sizes of nano silica in cement paste. An extensive regime of experimental analysis was carried out to determine the effect of nano silica in the cement paste. Through these experiments the heat of hydration of multiple cement mix designs were measured. After that, the concentration of calcium hydroxide was recorded through X-ray diffraction. Then, the crystallographic structures were examined through scanning electron microscopy. Finally, the compressive strength was determined for each cement paste mixture. Through these experiments it was found that as the silica particles decreases in size and incorporate a wider gradation of sizes, the calcium silicate hydrates became more rigid; this increased the compressive strength.