Engineering Properties Investigation of Soft Clay as Potential Subgrade Material

Abstract

Highway pavement design using soft clay soil as a subgrade is always a great challenge and can cause problems such as roadbed instability and soil settlement. To overcome this problem, the knowledge of the subgrade soil characteristic should be studied first because it needs to be considered during the design phase of pavement. This study was conducted to investigate the engineering properties of soft clay that can be used as potential subgrade material. Some soil laboratory tests were performed to establish the engineering properties of the soft clay. From the standard proctor compaction test, the results revealed that the maximum dry density and optimum moisture content are 1.58 Mg/m³ and 20.15 %, respectively. The finding from the soil-water characteristic curve (SWCC) test indicates that the SWCC did not present a residual suction. The compression modulus and pre-consolidation pressure obtained from the compacted soil sample for the consolidation test are higher than the undisturbed soil sample. Based on triaxial test results, the effective cohesion acquired from the compacted soil sample is greater than the undisturbed sample. This research provides a reference for the study of soft clay engineering characteristics.