Effects of flue gas desulfurization gypsum incorporation and curing temperatures on magnesium oxysulfate cement

• Published in: Construction & building materials 2022-09, Vol.349, p.128718, Article 128718
• Main Authors: Li, Moxian, Gu, Kang, Chen, Bing
• Format: Article
• Language: English
• Subjects: Curing temperature; Flue gas desulfurization gypsum; Magnesium oxysulfate cement; Mechanical properties; Microstructure
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2022.128718

•Flue gas desulfurization gypsum is used to add to magnesium oxysulfate cement.•The macro and micro effects of the flue gas desulfurization gypsum admixture and curing temperature on magnesium oxysulfate cement was discussed.•Under 40 °C curing, MOSC exhibited an increase in strength as well as a significant improvement in water resistance. In this study, the industrial solid waste flue gas desulfurization gypsum (FGDG) was incorporated to the magnesium oxysulfate cement (MOSC). The study mainly focused on the effects of different dosages of FGDG and the initial curing temperature on characteristics of MOSC. The mechanical properties of MOSC were evaluated with compressive strength, softening coefficient and volumetric stability. The microstructure and hydration product composition of the cements were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed that with the increase of FGDG dosing, MOSC showed a trend of decreasing compressive strength. However, 40 °C curing can improve the compressive strength of MOSC. The 28-day compressive strength of MOSC could reach up to 56.6 MPa under 40 °C curing, which was 12.5 % higher than that under 20 °C curing, and the softening coefficient could reach 0.99. Besides, it was confirmed by SEM and XRD that the curing at 40 °C curing contributed more to the generation of hydration product 5 Mg(OH)2·MgSO4·7H2O in MOSC, and the structure showed compactness. The microstructural analysis was consistent with the results of mechanical property tests.