Stabilization of Expansive Soil Using Bagasse Ash and Geopolymers to Suit as Subgrade in Flexible Pavement

Abstract

Expansive soils are considered problematic due to their sensitivity to moisture changes, leading to ground heave or settlement that damages structures and causes major economic losses. To address this, stabilization using industrial waste materials offers a cost-effective and eco-friendly solution. An eco-friendly, nontraditional stabilizer sugarcane bagasse ash (SCBA) and geopolymer was used for soil improvement. The dry soil–SCBA blend was activated with a alkaline solution composed of sodium metasilicate and sodium hydroxide in a fixed 70:30 ratio respectively. Laboratory tests were conducted to analyze the influence of varying percentages of sugarcane bagasse ash on varying percentage of geopolymers. Differential free swell Test, Modified Proctor Compaction Test, Atterberg Limits, and California Bearing Ratio (CBR) tests were performed. The Atterberg Limits, Dry Density and CBR of the Expansive soil has been improved on addition of 10% Bagasse ash and 3% Geopolymers as an optimum percentages. The present study demonstrates that the combination of industrial waste and chemical additives can be an effective, economical, and sustainable technique for the stabilization of expansive soil.

Introduction

Expansive soils, commonly known as black cotton (BC) soils, cover around 20% of India and are characterized by significant volume changes due to moisture variations. Their high montmorillonite content causes pronounced swelling when wet and shrinkage when dry, leading to cracking and structural instability. These soils, typically formed from the chemical weathering of basalt and trap rocks, exhibit high plasticity with liquid limits of 50–100%, plasticity indices of 25–65%, and shrinkage limits of 8–18%. Because of their unstable nature, they pose major challenges for foundations, pavements, and other civil engineering structures, necessitating effective stabilization techniques.

The study aims to:

1. Determine the properties of expansive soil.

2. Evaluate the effect of various dosages of Bagasse Ash (6–12%) and determine its optimum content.

3. Investigate the influence of different percentages of geopolymers (1–3.5%) on soil strength.

4. Conduct cyclic plate load tests on treated and untreated soil subgrade models.

Expansive soil samples were collected from Thummalapalli village (Andhra Pradesh), prepared, and tested. Sugarcane Bagasse Ash (SCBA) was obtained from a local sugar industry and its chemical composition was analyzed. Geopolymers made from sodium hydroxide and sodium silicate were used as eco-friendly soil stabilizers due to their strong alumino-silicate bonding and durability benefits.

Mix proportions included 6–12% Bagasse Ash for determining the optimal level, followed by adding 1–4% geopolymers to the optimally stabilized soil.

Conclusion

1) It is observed from the laboratory test results that the Differential Free Swell Index of Expansive soil has been reduced by 55% on the addition of 10% Bagasse Ash (BA) and it has been further reduced by 82% with an addition of 3 % Alkali activated geopolymer (AAG) when compared with untreated Expansive Soil. 2) It is observed from the laboratory test results that the Liquid limit of Expansive soil has been decreased by 18.6% on the addition 10% BA of and it has been further decreased by 36.38% with an addition of 3% AAG. 3) It is observed from the laboratory test results that the Plastic limit has been increased by 8.82% on addition of 10% BA and it has been further increased by 25.68% with an addition of 3% AAG. 4) It is observed from the laboratory test results that the Plasticity Index has been decreased by 38.44% on addition of 10% BA and it has been further decreased by 81.12% with addition of 3% AAG. 5) It is observed from the laboratory tests that the OMC of the Expansive soil has been decreased by 23.84% on the addition of 10% BA and it has been further decreased by 39.23% with addition of 3 % AAG. 6) It is observed from the laboratory tests that the MDD of the Expansive Soil has been increased by 7.2% on the addition of 10% BA and it has been further increased by 46.15% with addition of 3% AAG. 7) It is observed that the CBR of the Expansive Soil has been increased by 238.15% on the addition of 10% BA and it has been further increased by 443.42% with addition of 3% AAG. The addition of Bagasse ash and Geopolymers improved particle bonding and reduced the plasticity of Expansive soil , leading to a notable increase in CBR strength. These enhancements siginificantly boosted the soil load bearing capacity, making the treated Expansive soil suitable and durable for use as a effective pavment subgrade material.

References

[1] Niken Silmi Surjandari, Noegroho Djarwanti, Nafisah Umri Ukoi ENHANCING THE ENGINEERING PROPERTIES OF EXPANSIVE SOIL USING BAGASSE ASH. Civil Engineering Department, Engineering Faculty, Sebelas Maret University, Jl. Ir. Sutami 36A Surakarta 57126, Central Java, INDONESIA [2] Amit S. Kharade, Vishal V. Suryavanshi, Bhikaji S. Gujar, Rohankit R. Deshmukh. Waste product ‘bagasse ash’ from sugar industry can be used as stabilizing material for expansive oils Assistant Professor, B.E Students, Department of Civil Engineering, TKIET, Warananagar, Maharashtra, India. [3] Hayder Hasan, Liet Dang, Hadi Khabbaz, Behzad Fatahi and Sergei Terzaghi Remediation of Expansive Soils Using Agricultural Waste Bagasse Ash. University of Technology Sydney (UTS), Sydney, AustraliaARUP, Australasia Geotechnics. [4] Srinivasa Reddy K and Sai Vivek P BTECH-Student, Dept. of Civil Engineering, K L University, Guntur, A.P, INDIA. Syam Chambrelin K, Associate Professor, Dept. of Civil Engineering, K L University, Guntur, A.P, INDIA. STABILIZATION OF EXPANSIVE SOIL USING BAGASSE ASH. [5] Himani Saini [1], Jitendra Khatti [2], Dr. Biswajit Acharya [3] STABILIZATION OF BLACK COTTON SOIL BY USING SUGARCANE BAGASSE ASH.[1] M. Tech Student, Civil Engg. Dept, University Department, RTU, Kota [2] Ph.D. Scholar, Civil Engg . Dept, University Department, RTU, Kota [3] Associate Professor, Civil Engg. Dept, University Department, RTU, Kota. [6] C. Rajakumar and T. Meenambal Experimental Study of Bagasse Ash Utilization for Road Application on Expansive Soil. Department of Civil Engineering, Karpagam College of Engineering, Coimbatore, Tamil Nadu, India. Department of Geotechnical Engineering, Government College of Technology, Coimbatore, Tamil Nadu, India. [7] IS: 2720 (Part 16)-1987, \"Laboratory Determination of CBR\", Bureau of Indian Standards, New Delhi. [8] IS: 2720 (Part 5)-1985, \"Determination of Liquid and Plastic Limit\". Bureau of Indian Standards, New Delhi.

Copyright

Copyright © 2025 Dr. D. Koteswara Rao, M. Hillari. 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.