Abstract: A large amount of dredged sludge is generated in the process of many large-scale dredging projects in China, so how to dispose of dredged sludges with high water content, low bearing capacity and strong contamination have always been a practical engineering problem that needs to be solved. In this paper, the activated MgO-GGBS is used to solidify the sludge, and the mechanical properties of the solidified sludges are evaluated through the unconfined compression test; and combined with XRD, SEM and other microscopic tests, the changes of the mineral composition and microscopic morphology of solidified sludges are analyzed to reveal the solidification mechanism of the activated MgO-GGBS solidified sludges. The results showed that: the strength of the activated MgO-GGBS solidified soil increased significantly with the increase in the content of activated MgO, GGBS, and the growth of the age of maintenance, in which the content of alkaline exciters has a great influence on the strength of the solidified sludge, and the deformation modulus of the solidified sludge, E50, and the compressive strength of the solidified sludge showed a linear relationship between the alkaline additive content and the deformation modulus of the solidified sludge, E50, as well as the relationship between the compressive strength of the solidified sludge and the pH of sludge with the increase of the activated MgO additives. The more alkaline components consumed by the reaction as the growth of the maintenance time, and then the lower the PH; a large number of needle-rock-like crystals and the gelatinization product generation are the major reasons for the significant increase in the physico-mechanical properties of the solidified sludge with the activation of MgO-GGBS.

Key words: Solidified Dredged Sludges, Blast Furnace Slag, Physical and Mechanical Properties, Microscopic Mechanism