Prediction of compressibility and hydraulic conductivity of bentonitic mixtures

Abstract

Compressibility and hydraulic conductivity are the key parameters to ensure the structural integrity of landfill liner. The compressibility and hydraulic conductivity of compacted pond ash–bentonite and sand–bentonite mixes were determined from conventional consolidation tests. The results showed that both the compression index and coefficient of volume change increase, whereas the coefficient of consolidation decreases with an increase of bentonite content in the mix. Empirical models are proposed to predict the compression index and hydraulic conductivity of bentonitic mixtures from the basic soil parameters (specific gravity, liquid limit, void ratio and shape parameter), which have been compared and validated with existing models and experimental data sets. The compressibility characteristics of sedimented slurry and compacted mixes do not follow similar trends; therefore, two distinct empirical models are proposed in this study. The observed compression index values of the compacted specimens fall in the range of ± 20% from the line of equality, whereas the deviation is within ± 15% for sedimented slurry. Similarly, the estimated hydraulic conductivity values fall within ± 20% of the values predicted by the proposed empirical equation. Thus, the proposed empirical models may be used to predict the compressibility and hydraulic conductivity of compacted bentonitic mixtures.