A study on the performance of alkali-activated materials prepared by thermochemical treatment of ladle furnace slag

• Published in: Construction & building materials 2024-01, Vol.411, p.134560, Article 134560
• Main Authors: Fang, Minghang, Yi, Yuanrong, Ma, Wenqing, Lin, Yue, Li, Jie, Liu, Wei
• Format: Article
• Language: English
• Subjects: Chemical resistance; Compressive strength; Geopolymer; Heat resistance; Ladle furnace slag; Thermal activation
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2023.134560

In this paper, the effects of different calcination temperatures, flux types, and their corresponding additions on the thermal activation effect of the Ladle furnace slag (LFS) were investigated. A comparative analysis of the properties of the LFS-based geopolymer before and after thermal activation was carried out from a macroscopic perspective. The results showed that the 12CaO·7Al2O3(C12A7) in the LFS is more amorphous after thermal activation, leading to a prolongation in the setting time. When the calcination temperature reached 800 °C, the γ-C2S showed signs of transformation to β-C2S. This, in turn, undoubtedly enhanced the hydration properties of the LFS, as demonstrated by the compressive strength of the samples. In this regard, the compressive strengths of G-H-800, G-H-S5, and G-H-C10 after 28 days were 18.25 MPa, 18.47 MPa, and 24.38 MPa, respectively. They were found to be higher than those of the untreated sample G-Unheated at 8.0 MPa. In addition, the evaluation of the chemical resistance properties showed that the thermally-activated LFS-based geopolymer had good corrosion resistance in both NaCl and NaOH solutions, especially at high concentrations. The compressive strength loss rates of G-Unheated were 33.70% and 29.92% at NaCl and NaOH solution concentrations up to 2 mol/L, respectively. The lowest compressive strength loss rates of 9.21% and 17.83% could be achieved by LFS-based geopolymer after thermal activation under the same conditions. Nevertheless, the results of the high temperature resistance test showed that the compressive strength of the samples all increased at a temperature of 200 °C. However, when the temperature rose to 400 °C, the compressive strength of the samples decreased, except for G-Unheated, which showed a 2% increase in compressive strength. As the temperature was increased further, the compressive strengths of all samples were diminished. •Mineral rows of LFS can be optimized and modified by rapid air cooling after thermal activation.•LFS thermally activated geopolymer can achieve even better properties.•The addition of fluxes can further enhance the properties of geopolymer.