Stabilization of Soil Using Grinded Rice Husk Powder for Pavement Application

Abstract

This study examined the effectiveness of ground rice husk powder (GRHP) as a sustainable stabilizing material for improving the engineering properties of lateritic soil intended for pavement subgrade applications. Laboratory investigations were conducted on natural soil and soil samples stabilized with varying GRHP contents of 0%, 2%, 4%, 6%, 8%, and 10%. The experimental programme included Atterberg limits, Standard Proctor compaction, soaked California Bearing Ratio (CBR), and Unconfined Compressive Strength (UCS) tests. The results revealed a continuous reduction in liquid limit and plasticity index with increasing GRHP content, indicating reduced soil plasticity and improved stability. Compaction results showed a decrease in optimum moisture content and an increase in maximum dry density, with optimum performance achieved at 8% GRHP. Similarly, CBR and UCS values increased significantly with the addition of GRHP, attaining peak values of 19.6% and 166.7 kN/m², respectively, at 8% GRHP, before showing a slight decline at higher contents. These findings demonstrate that GRHP enhances the strength and load-bearing capacity of lateritic soil. The study concludes that ground rice husk powder is an effective, economical, and environmentally friendly soil stabilizer, with an optimum content of 8%, suitable for pavement subgrade improvement.

Introduction

Pavement infrastructure plays an important role in transportation and economic development. In many developing countries, pavements are constructed directly on natural soil, making the strength and engineering properties of the subgrade soil critical for pavement durability and performance. Weak soils, especially lateritic soils common in tropical regions, often lead to settlement, deformation, and premature pavement failure. Although traditional stabilization methods using materials such as cement, lime, and fly ash improve soil strength, they can be costly and environmentally harmful. As a result, researchers are exploring sustainable alternatives such as agricultural waste materials.

This study investigates the use of ground rice husk powder (GRHP) as an eco-friendly stabilizing agent for improving the properties of weak lateritic soils used in pavement subgrades. Soil samples were collected from Otuocha in Anambra State, Nigeria, an area known for frequent pavement failures. The soil was mixed with different proportions of GRHP (2%, 4%, 6%, 8%, and 10%) and tested using standard geotechnical tests including Atterberg limits, Standard Proctor compaction, California Bearing Ratio (CBR), and Unconfined Compressive Strength (UCS).

The results showed that increasing GRHP content reduced soil plasticity, indicating improved stability and lower swelling potential. Compaction tests revealed that optimum moisture content decreased, while maximum dry density increased up to 8% GRHP, indicating better particle packing. Strength tests also showed significant improvement: both CBR and UCS values increased with GRHP addition, reaching peak values at 8% GRHP before slightly decreasing at 10%.

Overall, the study concludes that ground rice husk powder effectively improves the plasticity, compaction, strength, and load-bearing capacity of lateritic soils, with 8% GRHP identified as the optimum stabilizer content. The findings highlight GRHP as a cost-effective, sustainable, and environmentally friendly material for pavement subgrade stabilization, while also promoting the beneficial use of agricultural waste.

Conclusion

This study evaluated the effectiveness of ground rice husk powder (GRHP) as a stabilizing agent for improving the engineering properties of lateritic soil intended for pavement subgrade applications. Laboratory investigations conducted included Atterberg limits, Standard Proctor compaction, California Bearing Ratio (CBR), and Unconfined Compressive Strength (UCS) tests. The results showed a progressive reduction in soil plasticity with increasing GRHP content, indicating improved soil stability. Compaction characteristics revealed a decrease in optimum moisture content and a corresponding increase in maximum dry density, with optimum performance achieved at 8% GRHP. Similarly, both CBR and UCS values increased significantly with GRHP addition, attaining peak values at 8% GRHP before exhibiting a slight reduction at higher stabilizer contents. These findings confirm that ground rice husk powder is an effective and sustainable stabilizing material, with 8% GRHP identified as the optimum content for enhancing the performance of lateritic soil as a pavement subgrade.

References

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Copyright

Copyright © 2026 Anene, W. C., Aniemeka, C. K., Chukwuebuka, I. W., Nwosu, C. P. A., Okide, K. F.. 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.