Stabilization of Expansive Soil Using Gum Arabic and Quarry Dust for Sustainable Highway Subgrade Application

Abstract

Aim: Expansive soils, characterized by their significant volume changes with moisture fluctuations, pose substantial challenges in highway construction due to their tendency to cause pavement distress and structural instability. This study investigates the potential of using a combination of Gum Arabic, a natural and biodegradable resin, and quarry dust, an industrial by-product, as sustainable alternatives for stabilizing expansive soils in highway subgrade applications. Methodology: Laboratory experiments were conducted on expansive soil samples treated with varying proportions of Gum Arabic and quarry dust. The geotechnical properties assessed included Atterberg limits, compaction characteristics, California Bearing Ratio (CBR), and Shear strength. Results: The soil was initially characterized as an inorganic clay of medium plasticity (CL) with a plasticity index of 29.46%, linear shrinkage of 10.71%, and specific gravity of 2.01, indicating high swell potential and poor suitability for engineering applications in its natural state. Stabilization was carried out using varying proportions of gum arabic (2%–8%) and stone dust (5%–20%) all expressed as percentages by dry weight of soil. CBR results showed that the optimum improvement occurred at 4% gum arabic and 10% stone dust, achieving a 14-day CBR of 9%, compared to 4.15% in the untreated compacted soil. Shear strength was also enhanced, with the maximum shear strength of 33.12 kN/m² recorded at 2% gum arabic and 5% stone dust, driven by increased apparent cohesion. Conclusion: The study concludes that moderate dosages of gum arabic and stone dust can significantly improve the strength characteristics of expansive soils, making them more suitable for subgrade applications. However, performance depends on proper dosage selection and adequate curing.