Stabilization of an Expansive Soil with Addition of Bitumen and Cement

Abstract

This study examined the effectiveness of stabilizing Expansive soil with combination of bitumen emulsion and cement. The research employs laboratory-scale model studies to simulate the behavior of expansive soil subjected to varying levels of bitumen and cement stabilization. Clayey soils naturally shrink and swell, which can have a major impact on buildings due to differential settlements. In semi-arid and arid regions of the world, expansive soils present a significant maintenance challenge for geotechnical engineers. Soil samples were obtained from bore hole 1 below 3M ground level, located at Ambedkar Colony, Tirupathi in Andhra Pradesh, and laboratory experiments such as dry density, Atterberg limits, Swelling, unconfined compression tests and California bearing ratio test (CBR) were performed with and without varied Bitumen percentages (2%, 4% ,6 %) and (2 %) Cement percentage. Experimental results indicate that the incorporation of bitumen and cement enhances the mechanical properties of expansive soils, reducing settlement and improving stability. Additionally, the study evaluates the long-term performance and environmental impacts of bitumen and cement stabilization techniques.

Introduction

The document studies the stabilization of expansive soils, which exhibit high swelling, shrinkage, and compressibility, causing serious geotechnical problems in construction. To improve soil performance, the study explores the use of bitumen and Ordinary Portland Cement (OPC) as stabilizing agents. These materials aim to enhance soil strength, reduce plasticity, and improve stability for foundations, embankments, and pavements.

The literature review shows that many researchers have successfully used cement, lime, and bitumen—either individually or in combinations—to improve properties like unconfined compressive strength (UCS), California Bearing Ratio (CBR), swelling potential, and permeability. Most studies report that increasing stabilizer content generally improves soil strength and reduces expansiveness.

The experimental work uses highly expansive clay collected from Tirupati, India, characterized by very high liquid limit, high plasticity index, and low strength. VG30 bitumen and OPC 53-grade cement are used as stabilizers. Laboratory tests such as Atterberg limits, compaction (OMC and MDD), and UCS are conducted to evaluate soil behavior.

Results show that both bitumen and cement reduce soil plasticity by lowering liquid limit and modifying plastic limit behavior. Compaction characteristics improve with increased stabilizer content, with optimum performance observed at specific mix proportions. UCS also increases with curing time and additive content, indicating improved strength and durability.

Conclusion

In this study, an expansive soil is stabilized with different amounts of bitumen, primarily consisting of cement. The objective of this research is to assess the effect of bitumen and cement mix on the unconfined compressive strength and CBR of the soil. Based on the results the following conclusions are made. Addition of bitumen and cement in varying percentages resulted in the increase of optimum moisture content (OMC) and an increase in the maximum dry density (MDD) up to 4% of bitumen + 2% of cement. Later on, with the increase in the admixture content beyond 4% of Bitumen + 2% cement the optimum moisture content is decreased. When higher contents of bitumen and cement are added, the amount of water adsorbed by the stabilizer in the mixing stage may get expelled under the compactive effort thus contributing to the decreased in MDD at higher stabilizer content and reduces after the addition of 6% of stabilizer. Similarly, The maximum value of UCS was obtained as 665 Kpa at 4% of bitumen and 2% of cement content which is 7 times than that of virgin soil.The samples attain significant strength and the gain depends on amount of binder and curing period.Similarly ,The maximum value of CBR was obtained as 25 % at 4% of bitumen and 2% of cement content which is 6 times than that of virgin soil.SEM and XRD studies confirm the formation of reaction products such as C–S–H and calcium hydroxide, which contributed to strength development in the stabilized soil.

References

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Copyright

Copyright © 2026 Lakshmi Manasa Gandikota, K. Mallikarjuna Rao. 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.