Investigation of Mode II Fracture Behavior of Alkali-Activated Mine Tailings

Abstract

ABSTRACT Reuse of mine tailings (MTs) rich in aluminum oxide and silicon dioxide to produce a geopolymer using an alkali activator is a sustainable approach to reduce the MTs’ environmental hazard. The fracturing behavior of mine tailing-based alkali activated materials under mode II loading has been largely unexplored. In this study, the mode II fracture tests have been adopted to examine the double-edge notched Brazilian disk (DNBD) geopolymer specimens under diametral loading. A mixture of MTS (85% wt.), class F fly ash (FA) (15% wt.), and 10 M NaOH solution with solid/liquid ratio of 14% was prepared, and using a cylindrical mold, specimens were cast and then cured at 70 °C. Mode II fracture toughness, the evolution of the crack tip opening and sliding displacement and the shear and minimum principal strain behavior were examined through strain mapping using the Digital Image Correlation (DIC) technique. The results showed that although DNBD is intended to provide pure mode II loading, mixed mode fracturing was observed, as there was still some crack surface opening. The study highlights the need for further investigation to fully understand the nature of mixed-mode fracture behavior in DNBD specimens and its implications for material characterization. With the rise in demand for mineral excavation and processing, significant quantities of mine tailings (MTs) are produced annually around the world. MTs are the waste rocks that are left over after the extraction of valuable metals has been completed during the mineral processing. As a result, there is a growing concern on how to manage the increasing amounts of MTs that are generated, and how to utilize them effectively. Based on the different phases, MTs can be stored either in impounding lakes for slurries or waste piles for solids (Kiventerä et al., 2018). Given their abundance and potential impact on the environment, it is important to explore ways to reuse these materials. MTs that contain sufficient quantities of aluminosilicates can be efficiently transformed into sustainable building materials by subjecting them to the process of alkaline activation and geopolymerization. The geopolymerization process creates a strong and durable material that can be used in various construction applications, including the manufacturing of bricks, tiles, and concrete (Davidovits, 2020; Muñoz Velasco et al., 2014; Provis & Van Deventer, 2009). Therefore, the utilization of MTs as a resource for construction materials can offer economic and environmental advantages (Singh et al., 2015; Zhang, Hedayat, Bolaños Sosa, Huamani Bernal, et al., 2021; Zhang, Hedayat, Han, et al., 2022; Zhang, Hedayat, Perera-Mercado, et al., 2022).