Laboratory Investigation on Strength Behavior of Gravel Soil Stabilized with Bitumen Emulsion and Cement

Soil is a fundamental material in all types of civil engineering construction, particularly in road infrastructure where the strength and durability of the subgrade soil are critical. When the natural subgrade does not meet the required strength criteria, stabilization becomes necessary to improve its engineering properties. This study focuses on enhancing the strength characteristics of gravelly soil using Medium Setting (MS) cationic bitumen emulsion, with Ordinary Portland Cement (OPC) as a secondary stabilizing agent. The experimental program involves a series of laboratory tests including specific gravity, grain size distribution, Atterberg limits, Modified Proctor Compaction, and California Bearing Ratio (CBR) tests under various conditions. Four distinct mixing scenarios were evaluated, varying the proportions of bitumen emulsion and cement, as well as curing durations. The influence of these parameters on the maximum dry density and CBR values of the stabilized soil was analyzed. Results indicate that the inclusion of 3% bitumen emulsion along with 2% cement, followed by a curing period of 5 hours, yields the most significant improvement in strength. This combination resulted in a notable increase in maximum dry density and up to a 50% improvement in CBR value compared to untreated soil. These findings confirm that the combined use of bitumen emulsion and cement can effectively enhance the load-bearing capacity of gravel subgrade, offering a cost-effective and sustainable solution for road construction.