Abstract:

Traditional main solidified materials (cement) and auxiliary materials (fly ash and gypsum) are used for solidifying sludge of East Lake of Wuhan. Based on the results of unconfined compressive strength test and triaxial shear test, the strength and characteristics of sludge solidified by the combination of different materials and mixture ratios are determined. Experimental results show that the role of cement is the dominant additive during solidification of sludge. The role of fly ash is equivalent to reducing the initial water content of sludge, and the early strength of solidified silt has been increased rapidly. The gypsum is conducive to the early strength formation of solidified sludge; and its role is shown throughout the solidifying process continuously. The model of stress-strain curve has been transitioned gradually from strain softening to strain hardening with the increase of water content of sludge samples which are solidified by cement only. Also the effect of the changing confining pressure on strength of solidified silt has been weakened gradually with the increasing water content. The model of stress-strain curve has been transitioned from strain softening to strain hardening because of adding auxiliary solidified material to sludge. The 20% cement, fly ash for 3 times the cement volume, and gypsum for 30% of the cement volume are the optimum mixture ratio for different water content sludge of East Lake. The research results will be contributed to the sediments treatment of East Lake as well as the foundation treatment and environmental renovation of the sludge stock yard.

Key words: sludge, solidification, strength, triaxial test