Study on Characteristics and Application of High Plastic Clay Filling for In-service Highway

Clearing the engineering characteristics of high plastic clay and its engineering application are the basis for rational use of high plastic clay to fill the embankment. In this study, a series of water content tests, relative density tests, liquid and plastic limit tests, the grain size analysis tests, compaction and California Bearing Ratio (CBR) tests were carried out based on high plastic clay of diseased subgrade along west-section of Hainan Beltline Freeway. The relationships between CBR and water content, coarse particle content and compaction energy were studied. The results indicated that water content, coarse particle content, and compaction energy had significant effect on CBR, and water content is the main impact factor on CBR values. The maximum CBR water content was greater than the optimal water content by 4% to 5%. The performance of CBR and dry density had obvious distinction under different consistency and compaction energy. The equilibrium water content of high plastic clay subgrade during highway running period was near the plastic limit, which is 6% to 13% higher than the optimal water content. Base on the indoor test results, the problems related to the application of high plastic clay in subgrade filling were analyzed considering the characteristics of highway engineering and climate in Hainan province. It was concluded that high plastic clay could be directly used for embankment filling when the compaction energy conducted under the maximum CBR water content.