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Volume change behavior of lime treated gypseous soil — influence of mineralogy and microstructure

Jha, Arvind Kumar / Sivapullaiah, P.V.

Abstract Series of oedometer tests and micro-analytical studies (XRD, SEM and EDAX) have been carried out to investigate the influence of varying gypsum content on swell, compressibility and permeability of lime treated montmorillonitic soil after curing for different period. Immediate swell is observed on inundation of compacted samples with water and continuously increased with gypsum content. However, changes in swell are found to be marginal with curing. This is attributed to the formation and growth of ettringite crystals by ionic reactions of aluminum–calcium–sulfate in the presence of water which is confirmed through detailed micro-analysis. The higher swell in uncured specimens and gradual reduction in swell with increase in curing periods are due to relative dominance of formation and growth of ettringite and cementitious compounds, respectively. Also, the ionic reaction products are found to bear a significant influence on the compressibility and permeability behavior.

Highlights • Effect of curing on swell behavior of lime treated gypseous soil. • Compressibility behavior of lime treated gypseous soil at different curing periods. • Permeability of lime treated soil with gypsum content and change in void ratio. • Detailed micro-analytical (XRD, SEM and EDAX) studies of uncured and cured samples. • Mechanism of volume change behavior of lime treated gypseous soil.