Hydraulic Conductivity of Fly Ash–Montmorillonite Clay Mixtures

Sujit Kumar Pal, Ambarish Ghosh

Indian Geotechnical Journal 43(1): 47-61

2013


ISSN/ISBN: 0971-9555
DOI: 10.1007/s40098-012-0033-3
Accession: 036650503

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Abstract
This study presents the hydraulic conductivity characteristics of fly ash mixed with varying percentages of montmorillonite clay. Fly ash produced by thermal power plants may contain different toxic metals and creates environmental problems like leaching and dusting; leaching of these metals may contaminate the ground water. To mitigate these problems attempts have been made to find out possible application of fly ash as safe construction materials like fill materials, liners and covers. Previous studies show scarcity of data on the hydraulic conductivity characteristics of fly ash montmorillonite clay mixes. Nine different types of fly ash samples collected from different thermal power plants of Eastern part of India have been mixed with varying percentages (i.e., 0, 20, 30, 40, and 50 %) of montmorillonite clay on dry weight basis of mixes. Total 45 numbers of mixes have been tested. Falling head hydraulic conductivity tests have been carried out, compacted at maximum dry density (MDD) and optimum moisture content (OMC) obtained from standard Proctor (AASHO) compaction tests. The values of hydraulic conductivity for specimens of mix with 50 % montmorillonite clay decrease to the range of 10?10 10?11 m/s from the range of 10?06 10?07 m/s of fly ash alone. Effects of flow period, montmorillonite clay content, MDD, OMC, liquid limit, plasticity index, initial void ratio, initial degree of saturation and free swell index on hydraulic conductivity of fly ash montmorillonite clay mixes have been discussed. The values of hydraulic conductivity decrease with increase of flow period, liquid limit, plasticity index, MDD, initial degree of saturation and free swell index, and with decrease in initial void ratio of mixes. Mixes of fly ash and montmorillonite clay may find potential application as liner material.

Hydraulic Conductivity of Fly Ash–Montmorillonite Clay Mixtures