Alkali-Activated Binders Based on Tungsten Mining Waste and Electric-Arc-Furnace Slag: Compressive Strength and Microstructure Properties

Abstract

The valorization and reusing of mining waste has been widely studied in recent years. Research has demonstrated that there is great potential for reusing mining waste for construction applications. This work experimentally investigated the strength development, pore structure, and microstructure of a binary alkali-activated binder. This is based on tungsten mining waste mud (TMWM) and electric-arc-furnace slag (EAF-Slag) using different proportions of TMWM (10, 20, 30, 40, and 50 vt.%). The precursors were activated using sodium silicate (Na2SiO3) and potassium hydroxide (KOH 8M) as alkaline activator solution with solid:liquid weight ratio = 3. Pastes were used to assess the compressive strength of the blended binder and their microstructure. The reaction products were characterized by X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), and Fourier transform infra-red (FT-IR) spectroscopy, while the porosity and the pores size properties were examined by mercury intrusion porosimetry (MIP). The results show that the partial replacement of TMWM with EAF-Slag exhibited better mechanical properties than the 100TM-AAB. A maximum strength value of 20.1 MPa was obtained in the binary-AAB sample prepared with 50 vt.% TMWM and EAF-Slag. The pastes that contained a higher dosage of EAF-Slag became more compact with lower porosity and finer pore-size distribution. In addition, the results obtained by SEM-EDS confirmed the formation of different types of reaction products in the 100TM-AAB, 100FS-AAB, and the binary-AABs mixtures such as N-A-S-H, C-A-S-H and (N, C)-A-S-H gels frameworks in the system as the major elements detected are Si, Al, Ca, and Na.

Evaluation on the Mechanical Properties of Ground Granulated Blast Slag (GGBS) and Fly Ash Stabilized Soil via Geopolymer Process

“…This is significant to the change in the matrix structure of the geopolymer bonds affected by the addition of GGBS and fly ash [ 45 , 46 ]. The altering peaks which shift the wavenumbers of Si–O–T asymmetric stretching and Si–O–T bending vibration, from 996.62 to 1013 cm −1 and 678.78 to 784 cm −1 of geopolymer soil samples indicated that the stabilization/solidification process of the geopolymer is a chemical reaction and the geopolymerization is active at room temperature [ 60 ]. This finding is in line with a previous study conducted by Sedira et al [ 60 ] that reported a shift in peaks to increase the wavenumbers of Si–O–T asymmetric stretching and Si–O–T bending vibration, clearly indicated that the alkali-activated could cause an increase in the compression strength.…”

“…The altering peaks which shift the wavenumbers of Si–O–T asymmetric stretching and Si–O–T bending vibration, from 996.62 to 1013 cm −1 and 678.78 to 784 cm −1 of geopolymer soil samples indicated that the stabilization/solidification process of the geopolymer is a chemical reaction and the geopolymerization is active at room temperature [ 60 ]. This finding is in line with a previous study conducted by Sedira et al [ 60 ] that reported a shift in peaks to increase the wavenumbers of Si–O–T asymmetric stretching and Si–O–T bending vibration, clearly indicated that the alkali-activated could cause an increase in the compression strength. This finding proves that the geopolymerization method effectively increases the mechanical and physical properties of the soil based on the increase in compressive strength of the geopolymer soil with GGBS and fly ash.…”

Cement-based mortars production applying mining residues treated with an electro-based technology and a thermal treatment: Technical and economic effects

“…mortar, concrete), for binder and aggregate partial replacement in building materials. Alkali activated products [8] and pozzolanic materials [9] were successfully produced with tungsten mining residues. The durability of conventional products may be enhanced in terms of resistance to abrasion and acid attack due to a lower water absorption [10].…”