Mitigation Strategies for Strength Reduction in Lime-Stabilised Sulphate Bearing Kuttanad Marine Clays

Presence of sulphates in lime-stabilised soils can lead to a reduction in long term strength, which can have adverse effects on construction and engineering projects. The present study focuses on addressing the challenges posed by sulphate content in lime-stabilised Kuttanad marine clays. By introducing 6% lime and 4% sulphates (sodium sulphate and lithium sulphate) to untreated clay, the research aims to investigate the effect of sulphates in these clays. To mitigate sulphate-related issue, barium hydroxide, in both its pure laboratory form and the commercial variant “baryta,” was employed to develop an effective mitigation strategy for strength reduction. Unconfined compression tests were conducted on lime-treated clay both with and without additives, immediately after preparation and over 1 week, 1 month, 3 months, 6 months, 1 year and 2 years of curing. Test results indicated that both sodium sulphate and lithium sulphate negatively impact the strength gain of lime-stabilised clay, with lithium sulphate having a more detrimental effect. There was a consistent improvement in shear strength with the addition of both barium hydroxide and baryta. The results of SEM and XRD analysis also align with the above findings. When twice the predetermined quantity of baryta was added, it outperformed pure barium hydroxide in terms of shear strength enhancement. The cost-effective nature of baryta, being a mere quarter of the price of pure barium hydroxide, makes it a viable alternative for addressing the strength loss in lime-stabilised sulphate bearing Kuttanad marine clays.