Experimental Study On The Strength Behavior Of Cement Stabilized Mud At High/ultrahigh Water Content

Most of the land reclamation projects have to use the dredged marine mud as the filling material.However,the reclaimed ground filled with the dredged marine mud usually has high water content and extremely low strength,and as a result,construction equipments for subsequent ground improvement can hardly access to the site.Use of cement stabilization technology is able to solve the accessibility problem by forming a Cement Stabilized Mud at High Water content(referred to as HW-CSM from hereon)layer or Flocculated and Stabilized Mud at Ultrahigh Water content(referred to as UW-FSM from hereon)layer.The HW-CSM and UW-FSM are different than the traditional cement treated clay,and their engineering properties still remain unclear.Hence it is of practical importance to study the strength behavior of HW-CSM and UW-FSM.In this thesis,a series of Unconfined Compression Tests(UCTs)are first conducted to acquire the unconfined compressive strength of different HW-CSM samples with different mixing proportions and different types of cement and clay.The influencing mechanism of these factors on strength development is identified based on the UCT data.An empirical model is proposed to characterize the influence of mixing proportion and the full-stage strength development behavior.This model can provide reasonable guidance for determining the rational mix proportion in practice.Subsequently,UCTs are performed on HW-CSM samples cured under non-standard conditions to analyze the strength development behavior of HW-CSM under different curing temperatures and/or under different curing stresses.Results indicate that a higher curing temperature or curing pressure have a significant impact on the strength of HW-CSM.Based on the experimental data,two strength models are developed to characterize the curing temperature effect and the curing stress effect respectively.These models can provide reference for the adjustment of mix proportion of in-situ HW-CSM under non-standard curing conditions.Finally,a number of deposition experiments and vane shear tests are conducted on the UW-FSM samples and the Cement Stabilized Mud at Ultrahigh Water content(referred to as UW-CSM)samples.The difference in the deposition behavior and strength development characteristics between the UW-FSM and UW-CSM are compared,and the influence of effective initial water content on the strength development of UW-FSM is further studied.Results well demonstrate the feasibility and efficiency of the proposed FSCM.