Evaluation of static segregation of cemented gangue-fly ash backfill material using electrical resistivity method

Static segregation of a cemented gangue-fly ash backfill material (CGFBM) presents a harmful impact on its mechanical and pipeline transportation performances. To evaluate the static segregation of a CGFBM in real time, electrical resistivity (ER) method is proposed by monitoring the ER change at different depths. The static stabilities of various mixtures with different mass concentrations of 74%, 76%, 78%, 80%, and 82% are evaluated in terms of the ER characteristics and derived segregation index (SI). Results showed that: for mixtures with relatively low mass concentrations (74% and 76%), the SI gradually decreases with increasing elapsed time after casting. 0.85 is the critical value. The CGFBM with a SI smaller and larger than 0.85 can be considered to have a low and high stability, respectively. The feasibility of the ER method is verified by bleeding test and image analysis method. (C) 2020 Elsevier Ltd. All rights reserved.