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Title |
Effects of Magnesium on Sulfate Resistance of Alkali-activated Materials
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Authors |
박광민(Kwang-Min Park) ; 조영근(Young-Keun Cho) ; 라정민(Jung-Min Ra) ; 김형석(Hyung-Suk Kim) |
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DOI |
https://doi.org/10.11112/jksmi.2017.21.1.109 |
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Keywords |
알칼리 활성화 결합재 ; 고로슬래그 ; 플라이애시 ; 황산염 저항성 ; 마그네슘 Alkali-activated materials ; Ground granulated blast furnace slag ; Fly ash ; Sulfate attack ; Magnesium |
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Abstract |
This paper describes the investigation into the durability alkali-activated materials(AAM) mortar and paste samples manufactured using fly-ash(FA) and ground granulated blast furnace slag(GGBFS) exposed to a sulfate environment with different GGBFS replace ratios(30, 50 and 100%), sodium silicate modules(Ms[SiO2/Na2O] 1.0, 1.5 and 2.0). The tests involved immersions into 10% sodium sulfate solution(Na2SO4), 10% magnesium sulfate solution(MgSO4), 10% magnesium nitrate solution(Mg(NO3)2) and 5% magnesium nitrate(Mg(NO3)2 + 5% sodium sulfate solution+ Na2SO4). The evolution of compressive strength, weight, length expansion and microstructural observation such as x-ray diffraction were studied. As a results, in case of immersed in Na2SO4, Mg(NO3)2 and Mg(NO3)2+Na2SO4 shows increase in long-term strength. However, for samples immersed in MgSO4, the general observation was that the compressive strength decreased after immersion. The most drastic reduction of compressive strength and expansion of weight and length occurred when GGBFS or Ms ratios were higher. Also, the XRD analysis of samples immersed in magnesium sulfate indicated that expansion of AAM caused by gypsum(CaSO4 ? 2H2O) and brucite(MgOH). The results showed that, an additional condition Mg2+ in which SO42- is the presence of a certain concentration, sulfate erosion has to be accelerated.
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