Influences of flocculant and retarder on solidification efficiency of cement in treatment of dredged mud slurry

It is usually necessary to build a working platform on the surface of the dumping site of dredged mud slurry for the purpose of rapid improvement of the dumping site so as to shorten the period of land occupation. Nevertheless, most of the existing methods for building the working platform need cumbersome manual work under extremely adverse conditions, and thus show very low construction automation and speed. To resolve this problem, a new method is proposed, i.e., the flocculation-solidification combined method (FSCM) for building the working platform based on the conventional cement stabilization method (CCSM). A series of laboratory model tests are performed to demonstrate the feasibility and necessity to substitute CCSM for FSCM in treatment of dredged mud slurry at extra high water content. Effort is also made to gain an insight into the influences of flocculant dosage and retarder dosage on the solidification efficiency of cement in treatment of mud slurry. The results indicate that FSCM is able to dramatically enhance the solidification efficiency of cement in treatment of mud slurry. When the optimal dosage of flocculant is added, the undrained shear strength produced by FSCM is at least 4.8 times larger than that produced by the corresponding CCSM. Moreover, introducing retarder into FSCM can further intensify the physical sedimentation/consolidation process, and thus promote the strength development at later curing age. In comparison with a FSCM case without adding retarder, the corresponding FSCM case with the optimal dosage of retarder shows a much higher undrained shear strength.