Synthesis of one-part geopolymers from alkaline-activated molybdenum tailings: Mechanical properties and microstructural evolution

Abstract

One-part geopolymers, an easily prepared and environmentally friendly cement alternative, play a significant role in mitigating CO2 emissions. Abundant in silicon and aluminum, molybdenum tailings present an ideal precursor for one-part geopolymers, particularly when addressing low reactivity limitations. In this study, molybdenum tailings undergo alkaline hydrothermal activation to serve as a precursor for synthesizing one-part geopolymers in conjunction with slag. With an 80% slag admixture, the compressive strength of the one-part geopolymer using activated molybdenum tailings reaches 44 MPa in 28 d, notably surpassing the strength of untreated tailings. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetry (TG) elucidate that amorphous C-A-S-H and N-A-S-H gels predominantly contribute to the strength. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyses reveal that activated molybdenum tailings act as alkali exciters and reaction materials, filling the gel product as microaggregate and forming a dense microstructure.