Experimental Evaluation of Gravel Sub-Base Stabilization for Sustainable Road Infrastructure

Stabilized gravel is increasingly recognized as a vital component in modern road construction, particularly for sub-base layers where strength, durability, and cost-efficiency are critical. This research presents a detailed laboratory investigation into the mechanical performance of gravel stabilized using a blend of cement, lime, and fly ash. The primary objective was to identify an optimal mix design and assess the structural improvements achieved through stabilization. The study involved standard laboratory testing procedures, including Modified Proctor Compaction, California Bearing Ratio (CBR), and Unconfined Compressive Strength (UCS) tests. The optimum mix was determined to consist of 6% cement, 4% lime, and 10% fly ash by dry weight of the gravel. Test results revealed a remarkable improvement in the mechanical behavior of the stabilized gravel. The CBR value reached 110%, substantially exceeding the minimum threshold of 80% typically required for sub-base applications. Similarly, the UCS of the stabilized mixture showed a significant increase compared to that of the untreated gravel, indicating enhanced load-bearing capacity and structural reliability. Overall, the findings affirm that the incorporation of cement, lime, and fly ash can transform conventional gravel into a high-performance sub-base material suitable for flexible pavement systems. This stabilization approach not only improves mechanical properties but also promotes sustainability through the reuse of industrial by-products. Further field-based studies are recommended to evaluate the long-term performance of the stabilized gravel under varying climatic and traffic conditions. Keywords: Gravel Stabilization, Sub-base Layer, Cement-Lime-Fly Ash Mix, California Bearing Ratio (CBR), Unconfined Compressive Strength (UCS), Sustainable Road Construction, Pavement Engineering, Soil Stabilization, Industrial Waste Utilization, Flexible Pavement Design