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Title |
Effects of Magnesium and Sulfate Ions on the Sulfate Attack Resistance of Alkali-activated Materials
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Authors |
박광민(Kwang-Min Park) ; 조영근(Young-Keun Cho) ; 신동철(Dong-Cheol Shin) |
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DOI |
https://doi.org/10.4334/JKCI.2017.29.4.415 |
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Keywords |
alkali-activated materials ; sulfate resistance ; ground granulated blast furnace slag ; fly ash ; magnesium ion |
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Abstract |
The purpose of this study is to investigate the effect of sulfate (SO4 2-) and magnesium (Mg2+) ions on sulfate resistance of Alkali-activated materials using Fly ash and Ground granulated blast furnace slag (GGBFS). In this research, 30%, 50% and 100% of GGBFS was replaced by sodium silicate modules (Ms(SiO2/Na2O), molar ratio, 1.0, 1.5 and 2.0). In order to investigate the effects of Mg2+ and SO4 2-, compression strength, weight change, lengh expansion of the samples were measured in 10% sodium sulfate (Na2SO4), 10%, 5% and 2.5% magnesium sulfate (MgSO4), 10% magnesium nitrate (Mg(NO3)2), 10% [magnesium chloride (MgCl2) + sodium sulfate (Na2SO4)] and 10% [magnesium nitrate (Mg(NO3)2 + sodium sulfate (Na2SO4)] solution, respectively and X-ray diffraction analysis was conducted after each experiment. As a result, when Mg2+ and SO4 2- coexist, degradation of compressive strength and expansion of the sample were caused by sulfate erosion. It was found that the reaction of Mg2+ with Calcium Silicate Hydrate (C-S-H) occurred and Ca2+ was produced. Then the Gypsum (CaSO4? 2H2O) was formed due to reaction between Ca2+ and SO4 2-, and also Magnesium hydroxide (Mg(OH)2, Brucite) was produced by the reaction between Mg2+ and OH-.
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