Buildings (Mar 2025)
Effect of Mix Design Parameters on the Properties of Dam Sediment/Slag-Based Geopolymer Mortars
Abstract
This study focuses on the use of dredged sediment (SD) from the dam for the synthesis of a geopolymer. The samples investigated in this work were prepared by mixing micronized and calcined sediment and ground granulated blast furnace slag (GGBFS), at different percentages (10%, 20%, 30%, 40%, and 50%). Furthermore, the influence of the molarity of the NaOH solution, which was used as an activator, as well as the impacts of the (SD/GGBFS) and (SiO2/Al2O3) ratios, and the use of different activator solutions, were also examined. In addition, the effects of the curing temperature and porosity were explored The results revealed that among the NaOH concentrations studied (6M, 8M, 10M, 12M, and 14M), 12M was identified as the optimal concentration, and the optimum SD/GGBFS ratio was 70/30. In addition, variation of the ratio (SiO2/Al2O3) allowed the identification of specific proportions for different binders. Indeed, a ratio (SiO2/Al2O3) equal to 4.45 offered an optimum compressive strength of 24.86 MPa, which is significantly higher than the 13.7 MPa obtained for the geopolymer based on sediment with a SiO2/Al2O3 ratio of 3.12 and 12M NaOH. Moreover, the curing temperature of 40 °C, for a period of 48 h, gave a mechanical strength value that was higher than that obtained at room temperature. Similarly, the optimal formulations led to a significant reduction in total porosity, especially when the molarity of the NaOH solution was high, with a GGBFS percentage of 30% achieving an optimal porosity value of 12.5%. Likewise, the X-ray diffraction, infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) analyses confirmed the formation of geopolymers with a compact structure, which paves the way for the development of innovative and sustainable eco-construction materials with a low-carbon footprint.
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