Potential Use of Coal Mine Overburden Waste Rock as Sustainable Geomaterial: Review of Properties and Research Challenges

Abstract

Coal is the cheapest and thus the preferred energy source in developing countries. A huge volume of coal mine waste rock, which is known as overburden (OB), is generated due to the surface mining of coal. Due to convenience and the restricted space, the OB is dumped adjacent to the mining area in huge tracts of usable land at large heights. The OB contains a wide range of particles that range from silt–clay size to large fragments of rock that are distributed randomly, which makes open dumping unsafe. Failure of the OB dump slopes causes considerable loss of life and property and disrupts mining operations. This state-of-the-art review highlights the severity of the problems that are associated with OB dumps and the potential to use OB as geomaterial for construction to avoid dumps and address the scarcity of natural geomaterials (e.g., sand and gravel) in the construction industry. Several studies reported OB characterization for on-site stability and reclamation or use as a construction material. Based on these studies, the physical, chemical, mineralogical, geotechnical, and geoenvironmental characteristics of the OB and their spatial and temporal variation are critically assessed. The OB properties vary widely based on the composition and gradation; however, previous studies clearly demonstrated the potential for using OB as a sustainable geomaterial, bridging the safety and sustainability problems of the mining and construction industries simultaneously. Comprehensive characterization and quantification of sustainability to overcome the current challenges when using OB as a sustainable construction material are highlighted in this study. This will help new researchers and practitioners worldwide validate their experimental results and devise solutions to mitigate the problems associated with OB in potential civil engineering applications. The question of how to replace traditional construction materials with efficient substitutes is crucial if we have to sustainably meet the demands of the upcoming decade. Different industrial wastes might hold the key to solving this issue on a widespread basis. When possible, suitable supplements might be employed to render these wastes construction ready. It is necessary to analyze the possibility of these wastes being utilized as construction material. Several laboratory investigations and small-scale field research have shown that various industrial wastes could be used in construction projects. Coal mine OB could be a significant supply of substitute construction materials as an alternative to various industrial wastes. However, very few research studies have examined the use of OB as a construction material. Comprehensive characterization and quantifying sustainability to overcome the current challenges of OB as a sustainable construction material are highlighted in this study. This study’s results could help new researchers and practitioners worldwide validate their experimental results and devise solutions to mitigate the problems associated with OB as a sustainable geomaterial for potential civil engineering applications.