Study on Stabilization of Expansive Soil Using Fly Ash and Lime

Abstract

Expansive soil covers over 51.8 million hectares of land area in India (mainly Black Cotton soil). The basic trait of these expansive soils is that they are highly hard while dry but lose all of their strength when wet. Because of this attribute of expansive soils, these soils provide issues all around the world that geotechnical engineers must address. Soil stabilization, which is frequently utilised in foundation and road pavement constructions, is one of the most significant features for construction purposes; this is because such a stabilization regime increases engineering qualities of the soil, such as volume stability, strength, and durability. The problematic soil is removed or replaced throughout this operation is completed;The current study attempts to stabilise black cotton soil from Shivnath River Pulgaon Durg Bhilai utilizing fly ash sourced from JayPee Cement Limited Bhilai . Expansive soils are stabilized using different quantities of this Mixture, such as 10%, 20%, 25% . Because fly ash has no plastic characteristic, the plasticity index (P.I.) of clay-fly ash mixtures decreases in value as the fly ash component increases. Finally, the addition of fly ash reduces the flexibility of the expanding soil while increasing its workability by modifying its grain size and colloidal response. 3 trials of different composition are prepared and tested.

Introduction

The foundation is essential for any land-based construction, and its strength heavily depends on the soil quality. Understanding soil properties and improving them through stabilization is crucial. This study focuses on stabilizing expansive soils using fly ash and lime in various proportions to enhance soil properties for construction.

Literature Review:
Previous studies have shown that fly ash improves the properties of black cotton and expansive soils by reducing liquid and plastic limits, increasing shrinkage limits, and improving the California Bearing Ratio (CBR). Combining fly ash with lime and other additives like blast furnace slag and gypsum significantly reduces soil swelling and increases compressive strength.

Materials and Methodology:

• Expansive soils shrink and swell with moisture changes, causing structural damage.

• Fly ash, a byproduct from coal-fired power plants, acts as a pozzolanic binder.

• Lime improves soil plasticity, reduces swelling, and enhances stability by chemical reactions with clay minerals.

Soil samples were collected near Shivnath River, Durg, and subjected to mechanical and additive stabilization methods using lime and fly ash mixtures.

Tests Conducted:

• Sieve Analysis

• Atterberg Limits (liquid and plastic limits)

• Modified Proctor Test (to find optimum moisture content and maximum dry density)

• California Bearing Ratio (CBR) test (to assess strength)

Results:

• Sieve analysis showed suitable grain size distribution for the soil.

• Modified Proctor test indicated the optimal soil stabilization mix is 10% lime, 15% fly ash, and 75% soil, achieving maximum dry density and optimum moisture content.

• CBR values increased significantly with the addition of lime and fly ash, indicating improved soil strength; from 8.74% in original soil to 22.7% in the stabilized mixture (10% lime, 25% fly ash, 65% soil).

Conclusion

Based on the results obtained and comparisons made in the present study, the following conclusions can be drawn: 1) The addition of fly ash initially reduced the Maximum Dry Density (MDD) value of the black cotton soil. It then increased as the fly ash concentration in the soil-fly ash combination increased. The highest MDD value was found in a soil combination with 15% fly ash content by weight that is 2.41 gm/cm3. Following that, the MDD levels constantly declined. 2) In un-soaked California Bearing Ratio (CBR) tests of soil with varied fly ash content, the CBR steadily climbed with the rise in fly ash content until its value reached 20% by weight of the overall mixture; it then declined. 3) For CBR 3 trials are performed and the CBR of that trial is taken whose CBR% at 2.5 mm penetration is greater than 5mm penetration. 4) CBR value of original soil sample is increasing hense we can conclude that this soil of composition mixture of 10% lime 25% Fly Ash and 65% soil sample is stable and good for relevant construction. As a result, using fly ash and lime as an addition reduces swelling while increasing the strength of the black cotton soil.

References

[1] Bose, B. (2012), “Geo-engineering Properties of Expansive Soil Stabilized with Fly Ash”, Electronic Journal of Geotechnical Engineering, Vol. 17, pp. 1339-1353. . [2] Kumar, A., Walia, B.S., and Bajaj, A. (2007), “Influence of Fly Ash, Lime and Polyester Fibers on Compaction and Strength Properties of Expansive Soil”, Journal of Materials in Civil Engineering, Vol. 19, Issue 3, pp. 242-248. [3] Malik, A., and Thapliyal, A. (2009), “Eco-friendly Fly Ash Utilization: Potential for Land Application”, Critical Reviews in Environmental Science and Technology, Vol. 39, Issue 4, pp. 333-366. [4] Misra, A., Biswas, D., and Upadhyaya, S. (2005), “Physico-mechanical behavior of self-cementing class C fly ash-clay minerals”, J. Fuel, Vol. 84, pp. 1410-1422. [5] Nath., P., and Sarker, P. (2011), “Effect of Fly Ash on the Durability Properties of High Strength Concrete”, Procedia Engineering, Vol. 14, pp. 1149-1156. [6] Phanikumar, B.R. and Sharma, R. S. (2004), “Effect of Fly Ash on Engineering Properties of Expansive Soil”, Journal of Geotechnical and Geoenvironmental Engineering. Vol. 130, Issue 7, pp. 764-767. [7] Nikumar, B.R., and Sharma, R. (2007), “Volume Change Behavior of Fly AshStabilized Clays”, Journal of Materials in Civil Engineering, Vol. 19, SPECIAL ISSUE: Geochemical Aspects of Stabilized Materials, pp. 67–74.

Copyright

Copyright © 2025 Shubham Gupta, Shivam Mishra, Ankur Chaturvedi, Narayan Singh, Dr. Umank Mishra, Dr. Kruti Jethwa . 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.