The bauxite beneficiation process in the Amazon generates a significant amount of tailings, which were historically stored in large basins without a designated purpose. One of these materials is clay obtained from the bauxite washing process, which is rich in Al₂O₃ minerals, primarily gibbsite and kaolinite, and currently lacks practical applications. This study aimed to explore an application of this tailing in the production of low-temperature geopolymers, considering its material characteristics and availability. Geopolymer synthesis was conducted following a Doehlert-type experimental design to evaluate the properties of the raw materials. The tailing was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetry-differential scanning calorimetry (TG-DSC), X-ray fluorescence (XRF), and inductively coupled plasma optical emission spectroscopy (ICP-OES), whereas the geopolymers were characterized by XRD, FTIR, and mechanical compressive strength testing. The mineralogical composition of the bauxite tailings consists of 45% of low-ordered kaolinite, 34% of gibbsite, and 21% of other minerals. Compressive strength values of the geopolymer produced ranged from 8.99 to 41.89 MPa, a good value for the type of geopolymer produced. The best compressive strength results were obtained at a low Na/Al ratio (0.5–0.6) and low curing temperature, which favors the application of the material for the synthesis of geopolymer, contributing to lower energy consumption and lower CO₂ emissions compared with usual geopolymers.

Alkali-activated materials (AAMs) are emerging materials with enhanced properties, including high compressive strength, low shrinkage, adjustable curing rates, resistance to acids and fire, and low thermal conductivity. These materials are synthesized by reacting aluminosilicate-rich precursors with highly alkaline solutions. Given these advantageous characteristics, this study investigates the synthesis of AAMs using bauxite washing clay from the Amazon region. Specimens were prepared with bauxite washing clay and a 1.3 M NaOH solution. The raw material was characterized by using X-ray diffraction (XRD), thermal analysis (TGA-DSC), Fourier transform infrared spectroscopy, and X-ray fluorescence. The specimens were further analyzed by XRD and tested for compressive strength, water absorption, apparent porosity, and acid leaching using HNO₃. The bauxite washing clay sample primarily comprises aluminum- and silica-rich minerals such as kaolinite and gibbsite, making it a suitable precursor for alkali activation. The synthesized specimens demonstrated low water absorption (18.61% ± 0.25) and significant mechanical strength (25.83 MPa ± 1.33). Regarding the potential release of metals and metalloids, the highest concentrations were observed for Al, Si, and Na - key elements in geopolymer formation.