Evaluation of Ponded Ash as a Sustainable Backfill Material

Abstract

The main aim of this research is to evaluate the applicability of ponded ash in the production of backfill material. Many experiments were conducted to analyze both fresh and hardened characteristics of backfill material developed from various ponded ash–sand ratio, cement, and air foam contents. Then, the behavior of the material in the actual field experiment was investigated through light falling weight deflectometer and excavation tests. All mixtures yielded excellent flowability performance, ranging from 2 to 25 mm. The compressive strength was found to increase as ponded ash and cement contents increased, but the strength decreased with an increase in air-foam content or number of freeze–thaw cycles. From the actual on-site experiment results, it is feasible to use up to 1% ponded ash in the backfill material as an economical alternative to the compacted granular fill.