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Properties of Alkali-Activated Slag Paste Using New Colloidal Nano-Silica Mixing Method

1
Department of Civil Engineering, Pusan National University, Busan 46241, Korea
2
Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
*
Author to whom correspondence should be addressed.
Materials 2019, 12(9), 1571; https://doi.org/10.3390/ma12091571
Received: 22 April 2019 / Revised: 10 May 2019 / Accepted: 10 May 2019 / Published: 13 May 2019
(This article belongs to the Special Issue Testing of Cement-Based Materials)
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Abstract

Previous studies of alkali-activated slag cement (AASC) using nano-silica have mentioned mostly powdered nano-silica and binder weight replacement methods, which have a rapid decrease in fluidity, a short setting time and a low nano-silica replacement rate (< 5%). In this study, colloidal nano-silica (CNS) was used and the mixing-water weight substitution method was applied. The substitution method was newly applied to improve the dispersibility of nano-silica and to increase the substitution rate. In the experiment, the CNS was replaced by 0, 10, 20, 30, 40, and 50% of the mixing-water weight. As a result, as the substitution rate of CNS increased, the fluidity decreased, and the setting time decreased. High compressive strength values and increased rates were also observed, and the diameter and volume of pores decreased rapidly. In particular, the increase of CNS replacement rate had the greatest effect on decrease of medium capillary pores (50–10 nm) and increase of gel pores (< 10 nm). The new displacement method was able to replace up to 50% of the mixing water. As shown in the experimental results, despite the high substitution rate of 50%, the minimum fluidity of the mixture was secured, and a high-strength and compact matrix could be formed. View Full-Text
Keywords: alkali-activated slag cement; colloidal nano-silica; mixing-water; mixing method alkali-activated slag cement; colloidal nano-silica; mixing-water; mixing method
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Kim, T.; Kim, J.H.; Jun, Y. Properties of Alkali-Activated Slag Paste Using New Colloidal Nano-Silica Mixing Method. Materials 2019, 12, 1571.

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