An Experimental Investigation on the Geoengineering Properties of Pond Ash-Bentonite Mixes

Abstract

An engineered landfill necessitates an impervious barrier to control the intrusion of groundwater into the landfill facilities and migration of leachate to the surrounding ground. The liner material should have sufficient shear strength along with highly impermeable. This paper aims at investigating certain features of a novel material that may serve as a landfill liner material as a substitute to sand-bentonite mixture. In this investigation, bentonite was blended with coarse pond ash ranging from 0 to 30% by weight of the total material in 5% intervals. The compaction characteristics, strength behavior, and permeability characteristics of these mixes are evaluated. It is observed that with bentonite content varied from 20 to 30%, the average hydraulic conductivity reduces from 3 × 10⁻⁷ to 9 × 10⁻⁹ cm/s for samples compacted to MDD at OMC corresponding to a compactive effort of 595 kJ/m³. However, when the samples are compacted with 2674 kJ/m³ energy; the hydraulic conductivity as mentioned above is achieved at a bentonite content of 15%. With the gradual addition of bentonite the cohesion of the mixture increases whereas the angle of internal friction decreases. Hence, it is concluded that sand-bentonite mixes can effectively be replaced by pond ash-bentonite mixture in the landfill liners.