Abstract：Making land by dredger fill provides a novel idea to solve the problem of lacking economic construction land in coastal area of Southeast China；but it is still a technical question to consolidate dredger fill foundation quickly and economically. Testing study that uses fly ash as additive to treat dredger fill slurry and to consolidate dredger fill foundation is carried out to find an efficient consolidation method. A number of experiments proves that the engineering geological properties of consolidated dredger fill has been improved. With the increase of the quantity of fly ash in dredger fill，the bearing capacity and shear strength of consolidated dredger fill are enhanced；and characteristics of consolidation are improved. There is close relationship between the changes of microstructure characteristics and improvements of engineering geological property. The structure type of consolidated dredger fill changes from flocculent structure to skeleton-flocculent structure，equivalent diameter of structure units becomes bigger，and a part of structure units became granular structure. The changes of microstructure directly lead to improvement of engineering geological property. It can be concluded that treating dredger fill slurry with fly ash is feasible and economical.
