Geotechnical characterization of fly ash composites for backfilling mine voids

Abstract

Abstract Backfilling of mine voids is mandatory to avoid subsequent ground stability problems in the form of subsidence. River sand and mill tailings have been widely used since a long time as backfilling materials. However, with a strict regulation banning river sand mining in India, research for developing alternative engineering materials substituting sand has gained importance. In the present study four fly ash composite materials (FCMs) was developed from the fly ash obtained from a captive thermal unit of Rourkela Steel Plant (RSP). The main constituent of the composite were fly ash, lime and gypsum. Detailed physical, and engineering properties were determined for the FCMs. Significant increases in the compressive strength were obtained after 56 days of curing time. A detailed SEM studies was undertaken to account for the increase in strength with time. The fly ash composite developed from RSP has potential to be used as substitute to sand for backfilling the mine voids.