A review on the geotechnical response of fly ash-colliery spoil blend and stability of coal mine dump

Abstract

Regressive coal mining to meet rising electricity demand has resulted in increased dumps of colliery spoil (CS) and fly ash (FA). These dumps must be adequately managed to avoid environmental hazards. Considering their loose deposition, they fail to attain geotechnical and geometrical stability. The present review article attempts to investigate the stability behaviour of FA-CS blend dumps in terms of geotechnical parameters. It also emphasizes studies that focus on determining the optimum percentage of FA to be used along with CS as a blend. Moreover, it also highlights resource management, implementation, and improvement of the FA-CS blend thereby enhancing geotechnical parameters, viz., compaction, unconfined compressive strength (UCS), calfornia bearing ratio (CBR), and shear strength. These studies have shown that the usage of around 20% of FA by weight in blend with CS, has improved geotechnical properties by 2.5 times their original value. Based on the review performed it is inferred that the blend of FA and CS can be laid effectively in exhausted mining sites and can be used in the construction of roads to these mining sites. • Presented recent state-of-the-art on colliery spoil. • Reviewed past studies related to unstable colliery spoil dump. • A blend of fly ash and spoil proved to be an effective ground improvement approach. • Documented studies related to the geotechnical performance of fly ash- spoil blend. • Safe and environmentally sustainable disposal. • Discussed the future potential of the fly ash-spoil blend in geotechnical engineering.