Power plant ash as a backfill material for subsidence mitigation and mining district recovery: a review and case study in Zonguldak, Turkiye

Abstract

This study investigates the use of fly ash (FA) as a sustainable backfilling material in underground coal mining in Zonguldak, Türkiye, aiming to reduce land subsidence, enhance void stability, and support ecological recovery. Laboratory analyses assessed FA’s physical, chemical, and hydraulic properties, while Darcy and channel-flow tests simulated drainage behaviour. Findings show FA is mainly fine-grained (94% < 0.5 mm) with hydraulic conductivity of 0.02–0.03 cm/s and high SiO₂, Al₂O₃, Fe₂O₃ contents (> 70%), indicating strong pozzolanic potential. Strength tests confirmed FA–cement blends effective, highlighting FA’s role in sustainable mining and circular economy.