Influence of the bentonite on the consolidation behaviour of soil-bentonite mixtures

Consolidation is one of the most important properties of the soil-bentonite mixture, which is used as a liner material at the waste disposal site, and needs to be understood for settlement analysis. The physical, chemical and mineralogical properties of the bentonite which influences the consolidation behaviour of the bentonite also influence the consolidation behaviour of the soil-bentonite mixtures. Effect of the physical, chemical and mineralogical properties of the bentonites on the various consolidation parameters of the 15 different soil-bentonite mixtures was evaluated. The experimental result showed a significant effect of these properties on the compression index (C _c), coefficient of consolidation (c _v) and the time for the 50% of consolidation (t ₅₀) of the soil-bentonite mixtures. The C _c of the mixtures was found to be increased with the increase in liquid limit, free swelling and clay fraction of the bentonites, as well as with the liquid limit of the soil-bentonite mixtures. The c _v for all the mixtures was found to be increased with the increase in the consolidating pressure, indicating the mixtures gets consolidated at a higher rate under a higher overburden pressure. The results also showed that irrespective of the overburden pressure, the c _v decreased with the increase in the liquid limit, free swelling, clay fraction and the exchangeable sodium percentage (ESP) of the bentonite present in the soil-bentonite mixtures. Similarly, the result of t ₅₀ for the mixtures was found to be increased with the increase in the liquid limit, swelling capacity and the ESP of the bentonite present in the mixture.