Taming the Expansive: Stabilizing Black Cotton Soil with Nano-Enhanced Waste Materials

Abstract

Black cotton soil, with its high shrink-swell potential, poses significant challenges for highway construction. This research investigates a novel approach to stabilize black cotton soil for subgrade applications by combining a nano-engineered chemical (Terrasil) with industrial (fly ash) and agricultural (rice husk ash) waste products. The study aims to evaluate the influence of these additives on the geotechnical properties of black cotton soil, including index properties, compaction characteristics, and strength parameters. By leveraging the synergistic effects of these materials, the research seeks to develop a sustainable and cost-effective solution for improving the engineering performance of black cotton soil while promoting the utilization of waste materials. The findings of this study will contribute to the development of more resilient and environmentally friendly highway infrastructure.

Introduction

This study explores the stabilization of black cotton soil—a problematic expansive soil prone to significant volume changes with moisture fluctuations—by using a combination of nano-engineered Terrasil, fly ash, and rice husk ash (RHA). The aim is to enhance the soil's suitability for highway subgrade applications, improving its engineering properties such as strength, compaction, and permeability.

Key Findings

• Consistency Limits: The addition of Terrasil reduced the liquid limit and plastic limit of the soil, indicating a decrease in plasticity and enhanced workability.

• Compaction Characteristics: An optimal Terrasil content of 0.06% increased the maximum dry density (MDD) to 1.53 gm/cm³ and decreased the optimum moisture content (OMC) to 23.6%, suggesting improved compaction.

• Strength Parameters: The unconfined compressive strength (UCS) and shear strength of the soil increased with the addition of Terrasil, reaching a peak at 0.06% Terrasil content.

• Permeability: The permeability of the soil decreased with the incorporation of Terrasil, indicating reduced water infiltration and potential for erosion.

Materials Used

• Terrasil: A nano-engineered chemical additive that modifies soil microstructure, enhancing strength and reducing permeability.

• Fly Ash: A byproduct of coal combustion, rich in pozzolanic materials that contribute to cementation and strength development.

• Rice Husk Ash (RHA): An agricultural waste product with pozzolanic properties, improving soil workability and strength.

Methodology

The study involved laboratory tests on untreated and treated black cotton soil samples, including:

• Index properties (liquid limit, plastic limit, plasticity index)

• Compaction characteristics (maximum dry density, optimum moisture content)

• Strength parameters (unconfined compressive strength, shear strength)

• Permeability

Treatments were applied in varying proportions to determine the optimal mix for soil stabilization.

Conclusion

This study investigated the effectiveness of Terrasil, in combination with fly ash and rice husk ash, in improving the geotechnical properties of black cotton soil. The results of the experimental program demonstrated that the addition of Terrasil, within a specific optimal range, significantly improved the engineering characteristics of the soil. A. Key findings include 1) Improved Consistency Limits: The addition of Terrasil generally resulted in a decrease in liquid limit and plastic limit, indicating a reduction in the soil\'s plasticity. This is beneficial as it can reduce the soil\'s susceptibility to volume changes due to moisture fluctuations. 2) Enhanced Compaction Characteristics: The optimal moisture content (OMC) and maximum dry density (MDD) were observed to vary with the addition of Terrasil. The results suggest that an optimal Terrasil content can be identified to achieve the desired compaction characteristics. 3) Increased Strength: The unconfined compressive strength and shear strength of the soil were observed to increase with the addition of Terrasil within a specific range. This indicates an improvement in the soil\'s load-bearing capacity and resistance to shear stresses. 4) Reduced Permeability: The permeability of the soil was observed to decrease with the addition of Terrasil. This is a significant finding as it can improve the soil\'s resistance to water infiltration and reduce the potential for erosion. Overall, the results of this study demonstrate the potential of Terrasil, in combination with fly ash and rice husk ash, as an effective stabilizer for black cotton soil. The findings suggest that the addition of Terrasil can significantly improve the engineering properties of this challenging soil type, making it more suitable for various construction applications.

References

[1] Amarjit Singh (1967). Use of lime-fly ash in soil stabilisation for roads, Jl. Of Indian RoadsCongress, vol-XXX-1,143. [2] Amos,D.F. and Wright,J.D.,1972, The effect of soil fly Ash on soil physical characteristics,Proc. Of Third Mineral Waste Utilisation Symposium, Chicago, pp. 95- 104. [3] Bell, F.G., 1993, Engineering treatment of soils, E & FN Spon Publishers, London. [4] Bhoominathan,A. and Hari,S.,1999, Behaviour of fly ash under static and cyclic loading,Proc.of Indian Geotechnical Conference, Calcutta,pp.324-326. [5] Bose, B. (2012), “Geo-engineering Properties of Expansive Soil Stabilized with FlyAsh”,Electronic Journal of Geotechnical Engineering, Vol. 17, pp. 1339-1353. [6] Cokca, E. (2001), “Use of Class C fly ash for the stabilization of an expansive soil”,ASCEJournal of Geotechnical and Geo environmental Engineering. Vol. 127, Issue 7, pp.568–573. [7] Cokca,E.,2001, Use of class-C fly ashes for the stabilisation of expansive soil, Jl.ofGeotechnical and Geo environmental engg.,vol.127,pp.568-573. [8] Gayathri, M., P. Singh, and M. Prashanth, Soil Stabilization using Terrasil, Cement andFly ash. i-Manager\'s Journal on Civil Engineering, 2016. 6(4): p. 31. [9] Hakari, U.D.and Puranik,S.C.,2010,Evaluation of swell potential and identification ofexpansive and problematic soils in civil engineering works by newly developed matrices basedon index and grain size properties, Electronic Journal of Geotechnical Engineering(EJGE),vol.15,pp.1712-1726. [10] Holtz, W. G., and Gibbs, H. J. (1956), “Engineering properties of expansive clays”Transactions ASCE. Vol. 121, pp. 641–677. [11] Indra ratna,B.,Nutalaya, P. and Kuganenthria, N.,1991, Stabilisation of a dispersive soil byblending with fly ash, Qtrly Jl. of Engineering Geology, vol.24,pp.275-290.

Copyright

Copyright © 2025 Amir Rashid Bhat, Er. Preetpal Singh Rihal. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.