Sedimentation of the fine-grained dredged slurry in the marine environment

Dredged slurry is used widely around the world for land reclamation as an important way to alleviate the lack of available land. This method involves hydraulically dredging slurry with extremely high water content to the site where soil is to be formed via sedimentation and consolidation. Therefore, a fundamental understanding of slurry sedimentation, especially in the marine environment, is very important if reclamation construction is to be done securely and economically. This paper investigates slurry sedimentation through laboratory sedimentation tests, considering the effects of the marine environment. It is found that (i) the sedimentation behavior of slurry prepared using seawater is significantly different from that of slurry prepared using distilled water and (ii) other hydrochemical conditions including salt (cation) types and concentrations also affect sedimentation behavior. A sedimentation model is proposed that is capable of quantitative characterization through defining several parameters associated with sedimentation type and sedimentation stabilization. The microscopic mechanism of sedimentation is revealed through scanning electron microscopy and zeta-potential measurements. Although specific to land reclamation construction in Tianjin, China, this study enhances the general understanding of slurry sedimentation affected by hydrochemical environments.