Physicochemical treatment of dredged clay slurry waste for land reclamation purpose

Abstract

Application of chemically solidified dredged marine clay as land reclamation fill can not only mitigate the issue of local scarcity of ideal filling material, but also allow significant volumes of unwanted marine clay arising from dredging to be disposed economically and ecologically. Nevertheless, treatment efficiency of pure chemical solidification at extra-high water content is very low or even marginal. This study aims to develop a new physicochemical method (PCM) for efficient treatment of dredged clay slurry waste at extra-high water content. It is essentially to reduce the equivalent water content by the flocculation component in the initial curing stage and solidify the dewatered clay slurry by the chemical solidification component in the later curing stage. A number of laboratory experiments are performed on clay samples treated by both the pure chemical method (CM) and PCM. Comparison results show that, when the initial water content of the dredged clay slurry is higher than 300%, the undrained shear strength of PCM treated marine clay slurry is 8 times larger than that of CM mix with the same content of chemical solidification component. This demonstrates well the feasibility and efficiency of PCM for land reclamation purpose.