محمد مقصودی

This study aims to analyze the effect of Ferro-silicomanganese slag (FSMS) as a precursor in systems with 8M and 12M NaOH concentration (NC) in the presence of 10% Ca(OH)2 (CH) and in combination with different percentages of the ground granulated blast furnace slag (GGBFS) on the performance of alkali-activated gels. Twelve mixtures were evaluated, including binary and ternary FSMS, GGBFS, and CH mixtures. The mechanical, transport and microstructural properties of alkali-activated materials were assessed through compressive strength, modulus of rupture, UPV, and modulus of elasticity, sorptivity, and surface electrical resistivity, as well as RCMT, XRD, FTIR, FESEM, and EDS tests. According to the findings, altering the NC had a minimal impact on the mechanical properties of GGBFS/CH-based binary mixtures. However, raising the NC from 8M to 12M resulted in a nearly 100% increase in compressive and modulus of rupture, a 20% increase in the UPV test, and a 40% increase in the modulus of elasticity of FSMS-based binary mixtures. The optimal amount of FSMS in ternary mixtures compared with GGBFS/CH-based binary mixtures resulted in comparable sorptivity and increased modulus of rupture and modulus of elasticity. In the matrix of GGBFS-based binary mixtures, the morphology of the dominant alkali-activated gel is different compared to ternary mixtures. FESEM and EDS results show that the dominant alkali-activated gel morphology with Ca/Si about 0.75 is a 3D aluminosilicate structure with a cross-linked network. Moreover, with Ca/Si about 1.4, the morphology of the gel is globule-shaped. Meanwhile, increasing the amount of GGBFS in the ternary mixtures raised the tortuosity of the gel network.