Abstract
Land reclamation forms one of the major civil engineering activities in Singapore. As the cost of sand is high, clay is being used as fill material. Contrary to conventional practice of mixing such clay into slurry to be pumped as a hydraulic fill, clay lumps were successfully used directly as fill in some reclamation projects. While in most of the cases the inter-lump voids are filled with water, in some occasions the inter-lump voids are filled with clay slurry, due to the presence of thick layer of very soft clay slurry in the seabed. The influence of the presence of clay slurry on the compressibility behaviour is evaluated in this paper by comparing with the case of a lumpy fill with the inter-lump voids filled with water. The study showed that the presence of slurry reduces the permeability of the system and consequently the rate of settlement. However, the end state of the system is not significantly affected.