Utilisation of expansive soils as highway embankment materials in humid environments

The objective of this paper is to propose a compaction control method that facilitates the use of expansive soil, as embankment material for highways in humid climates. Three types of expansive soils, utilised as general embankment fill in Southern China, were selected for investigating the physical, compaction, and shear strength properties. The compaction-control method was proposed based on the compaction curve revealed by the dry preparation method, associated with the corresponding soaked California bearing ratio. The site test and long-term monitoring were conducted in an embankment in Ningming, which was filled with compacted expansive soil controlled by the suggested method. The laboratory test results showed that the maximum dry unit weight obtained from the dry preparation method was less than that generated from the moist preparation method, while the optimum moisture content acquired from the dry preparation method was greater and closer to its natural moisture content. The moisture content corresponding to maximum CBR was 2% larger than the optimum moisture content. The in-situ monitoring results presented that the moisture content of the constructed embankment was close to its natural moisture content or plastic limit, the maximum settlement was 70.6 mm, and the maximum horizontal displacement was 20 mm.