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Journal of Nanomaterials
Volume 2014, Article ID 102392, 10 pages
http://dx.doi.org/10.1155/2014/102392
Research Article

Experimental Investigation and Theoretical Modeling of Nanosilica Activity in Concrete

1School of Architecture & Architectural Engineering, Hanyang University, Ansan 425-791, Republic of Korea
2Department of Architectural Engineering, College of Engineering, Kangwon National University, Chuncheon 200-701, Republic of Korea

Received 18 May 2014; Revised 16 July 2014; Accepted 27 July 2014; Published 11 August 2014

Academic Editor: Nageh K. Allam

Copyright © 2014 Han-Seung Lee et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This paper presents experimental investigations and theoretical modeling of the hydration reaction of nanosilica blended concrete with different water-to-binder ratios and different nanosilica replacement ratios. The developments of chemically bound water contents, calcium hydroxide contents, and compressive strength of Portland cement control specimens and nanosilica blended specimens were measured at different ages: 1 day, 3 days, 7 days, 14 days, and 28 days. Due to the pozzolanic reaction of nanosilica, the contents of calcium hydroxide in nanosilica blended pastes are considerably lower than those in the control specimens. Compared with the control specimens, the extent of compressive strength enhancement in the nanosilica blended specimens is much higher at early ages. Additionally, a blended cement hydration model that considers both the hydration reaction of cement and the pozzolanic reaction of nanosilica is proposed. The properties of nanosilica blended concrete during hardening were evaluated using the degree of hydration of cement and the reaction degree of nanosilica. The calculated chemically bound water contents, calcium hydroxide contents, and compressive strength were generally consistent with the experimental results.