A Study on the Optimal Mixture Ratio for Stabilization of Surface Layer on Ultra-Soft Marine Clay

Recently, as large constructions on the coast increase, application of a surface layer stabilization method, which is one of the improvement methods for dredged soft clay, have increased. However, there are few studies about this method. The purpose of this study is to clarify characteristics of ultra-soft marine clay and hardening agent, and to evaluate an optimal mixture ratio of hardening agent through the laboratory tests according to design of experiments. Laboratory test results were verified by statistical analysis and pilot tests. Laboratory tests were performed with hardening agents and test soils by the design of experiments, and regression equations according to relation of hardening agents materials and unconfined compressive strength were derived from the tests. Regression equations also verified its applicability to field by pilot tests. From the results of tests, it was found that hardening agent materials such as cement, slag, fly-ash, inorganic salts, häuyne, gypsum, etc. affect compressive strength. It was defined that optimal mixture ratio which satisfies the required compressive strength from the statistical analysis. Also, it was compared that the effect of ground improvement by cements and hardening agents through the pilot tests. This study will serve data for design or construction criteria of stabilization of surface layer on ultra-soft marine clay.