The Performance of the Improved Clay Soil on Road Subgrade

Abstract

Abstract The poor fillings of embankments cause insufficient strength and excessive deformation to road subgrade. This study took a kind of onsite over-wet red clay soil as the research sample with lime and cement as additives to improve it, which could be used as the subgrade filling. Laboratory experiments scanning electron microscopy (SEM), California bearing ratio (CBR), water absorption, and unconfined compressive strength (UCS) were conducted to analyze the performance of the improved soil. The results showed that the improved clay soil had rich fibrous components, enabling the UCS values of the improved soil to reach greater than 0.6 MPa on average at 6% proportion by weight, which meant a higher strength compared to plain soil. The variation of maximum dry density value and optimum water content value on compaction curves indicated that the improved red clay soil could reduce its sensitivity to water, making it easy to be compacted. With the increase in additive proportion, the CBR values increased while water absorption potential decreased significantly, showing that the improved soil was likely to hold stable humidity for the subgrade without becoming too humid or too dry. The application to road subgrade in the field proved good practicability and performance of the improved clay soil.