Volume Change Behavior of Fly Ash–Montmorillonite Clay Mixtures: Fid-Bau Portal

Volume Change Behavior of Fly Ash–Montmorillonite Clay Mixtures

Pal, Sujit Kumar / Ghosh, Ambarish

Abstract

This paper presents the consolidation and swelling characteristics of fly ash–montmorillonite clay mixes. Nine types of fly ash samples collected from different thermal power plants of the Eastern part of India have been used in this study. The amount of montmorillonite clay added to each fly ash sample is 10, 20, 30, 40, and 50%. The compression index ( $c_{c}$ ) of the fly ashes indicates that the rate of consolidation is very fast. With an increase in montmorillonite clay content from 0.0 to 50%, the compressibility of the fly ash–montmorillonite clay mix increases, irrespective of the type of fly ash. The value of the compression index ( $c_{c}$ ) of montmorillonite clay indicates that the embankments and fills made of fly ash–montmorillonite clay mixtures (i.e., 30, 40, and 50% of montmorillonite clay in the mix) and the structures constructed on such fills would suffer large deformation, whereas fly ash and fly ash mixed with 20% montmorillonite clay would not suffer large deformation. Specimens used for consolidation tests were compacted at the optimum moisture content (OMC) and the maximum dry density (MDD) obtained from standard Proctor compaction tests. Fly ash samples are nonswelling in nature, and the free swell index increases as the percentage of montmorillonite clay increases in the mixtures. Effects of the type of fly ashes, montmorillonite clay content in the mixes, permeability, and plasticity of fly ash–montmorillonite clay mixtures on compressibility of fly ash alone or in combination with montmorollonite clay mixes have been discussed herein. The effect of the percentage of montmorillonite clay and the plasticity index on the free swell index has also been highlighted.