Simultaneous Evaluation of Montmorillonite and Na/Ca Content for Assessing Unstabilized and Stabilized Natural Expansive Soils for Geoengineering Applications

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发表日期：

2024年11月12日

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Peddireddy Sreekanth Reddy,
K Anand Goud,
Bendadi Hanumantha Rao,
Krishna R. Reddy

摘要

The potential of natural expansive soils (NES) to substitute for highly swelling bentonite soils (BS) due to their similar properties is largely unexplored. The present study attempts to propose new engineering applications for NES. The novelty of this research lies in considering the combined montmorillonite content (MMC) and chemical parameters. Additionally, the study examines the efficacy of various additives in reducing swelling and improving the strength of stabilized soils. For this purpose, both the additive content and the inherent chemical properties of the soils and additives, are considered together. This combination has not been explored in previous studies. Under chemical parameters Cation Exchange Capacity (CEC) and calcium (Ca)/sodium (Na) ratio are considered. The analysis of results clearly shows that it is essential to consider montmorillonite content and chemical parameters together, as they significantly influence the macro-behavior of NES. The study suggests that when MMC, (Ca/Na)_L.S, and total CEC are (a) below 12% and 0.38, and 23 meq/100 g, NES are suitable as geomaterials, (b) in the range of 12–41%, 0.39–0.91, and 23–50 meq/100 g, NES require stabilization for practical implications, and (c) above 41%, 0.91–1.08, and 50 meq/100 g, NES are ideal as barrier materials. Regarding additive performance, the analyses reveal that most pre-treated and many post-treated NES did not meet the requirements for use as geomaterials. It is found that NES that exhibit a high to very high degree of expansion, even after amending with a suitable stabilizer, are the best substitutes for BS as a barrier material. Demonstrating the connection between micro-level parameters and the macro-behavior of NES is vital for researchers and field engineers to efficiently design structures to be built in or on expansive soils and to explore alternative uses for these soils.