Application of cement-solidified mud to filling projects can mitigate the local scarcity of sand and gravel filling material and dispose of significant volumes of dredged mud. Nevertheless

when the dredged mud is at extra-high water content (>300%)

the treatment efficiency of pure chemical solidification becomes very low. However

such problems can be effectively solved by treating mud slurry using the physicochemical composite method. As the quicklime has both the effect of flocculant and solidification agent

using quicklime to replace part of the cement may further increase the treatment efficiency. In this paper

the effect law of the replacement ratio of quicklime on physicochemical composite treatment of dredged mud slurries was studied via vane shear tests

and its solidification mechanism was revealed by XRD and FESEM tests. The results show that quicklime significantly impacts on the physicochemical composite treatment effect

and there is an optimal replacement ratio. Under this optimal replacement ratio

the quicklime can exert the dual effects of flocculation and solidification

which effectively increases the earlier and later strength of the treated mud specimens. From the microscopic test results

the treated mud samples at this optimal replacement ratio produce the highest amount of CSH/CAH/CASH

ettringite and other hydrated cementitious materials with the smallest pore gap. Therefore

quicklime can be used to replace part of the cement during the physicochemical composite treatment of dredged mud slurries in the actual project.