Mode I Fracture Behavior of Lightweight Concrete Made of Mine-Tailings-Based Aggregates

The exploration of mode I fracture behavior in lightweight concrete (LW-concrete) made from mine-tailings-based aggregates holds great significance in the realm of construction materials. This research is vital, as it offers crucial insights into the structural integrity of the material and its suitability for diverse applications. The utilization of mine tailings (MTs), abundant in aluminum oxide and silicon dioxide, and their transformation into lightweight aggregates (LWAs) signifies an environmentally responsible approach to address the environmental impact of MTs while reducing disposal costs. This study explored the fracture behavior of LW-concrete composed of mine-tailings-based aggregates, particularly under mode I loading. This aspect necessitates a comprehensive examination of this innovative material. Mode I fracture tests were performed on three-point bending beam specimens to better understand the fracture behavior. Using alkali-activation and palletization techniques, LWAs were produced using a blend of 30 wt.% fly ash type F and 70 wt.% MTs. The concrete mix incorporated a combination of coarse LWAs and natural, normal-weight fine aggregates. Specialized molds were employed for the direct casting of notched beam specimens, which were subsequently subjected to three-point bending tests after the curing process. The study revealed a mode I fracture toughness of 434.88 kNm^1/2, a crack tip opening displacement (CTOD) of 90.28 μm, and the characteristics of the fracture process zone (FPZ) measuring 2.88 mm, with comprehensive analysis conducted using Digital Image Correlation (DIC). 1. INTRODUCTION Natural aggregates find widespread applications in civil engineering and construction industry. They hold significant importance in the manufacturing of concrete (Guo et al., 2020), building roads (Ryms et al., 2015), surfacing asphalt (Qian et al., 2013), and other related applications. However, since natural resources are scarce and their utilization may have adverse environmental effects (Tabsh & Abdelfatah, 2009), there is an increasing interest in manufacturing lightweight aggregates (LWAs) utilizing waste materials like mine tailings (MTs) (M. Asadizadeh et al., 2023b, 2023a; Mostafa Asadizadeh et al., 2023, 2024; Yliniemi et al., 2017).