Experimental Study On Curing Effect Of Cement And Soil Curing Agent On Dredged Sludge

The dredged mud from this paper was taken from the river dredging project of Qinglian section of Jiangyou City.,Using cement and soil curing agent to solidify dredged sludge,Considering the effects of curing agent dosage and curing age,Conducted compaction test,direct shear test,unconfined compressive strength test,CBR test,water stability test and heavy metal precipitation test,The curing effect of curing agent on silt is studied from three aspects:mechanical properties of solidified silt,water stability and precipitation of heavy metals.Mainly achieved the following conclusion:?1?It is known from the compaction test of silt,The soil has the highest dry density at the optimum moisture content,The best compaction effect.?2?The CBR test,direct shear test and unconfined compressive strength test are used to study the mechanical properties of the silt after solidification and whether it meets the engineering requirements.According to the test results,The mechanical properties of the solidified silt have been significantly enhanced,Cement has better curing effect than soil curing agent,It works better when two curing agents are added at the same time.With the increase of the amount of curing agent and the length of curing age,The cohesive force,internal friction angle and compressive strength of the silt have just begun to grow faster.Then continue to grow but decrease,The CBR value of the silt after curing meets the minimum strength requirement of the roadbed filler,The optimum dosage of the composite curing agent is 2%soil curing agent+5%cement,The amount of cement should not be too high,Most economical in this dosage,At the same time,It is recommended that the time of maintenance age be as much as 7¹4 days in the project.?3?Unsolidified sludge has poor water stability,Collapsed in contact with water,The water stability of the silt is significantly enhanced after solidification,When the amount of curing agent is constant,With the extension of the age of maintenance,The unconfined compressive strength of the test piece increases after soaking,Faster growth at 7 days of age,Then as the maintenance age continues to extend,Its compressive strength increases less,At a certain time of age,Increasing the amount of curing agent can improve the unconfined compressive strength of the test piece after soaking.?4?The solid metal precipitation test of the silt after solidification is carried out by the acetic acid buffer solution method,Heavy metal content was determined by atomic absorption spectrometry.The test results show,Both cement and soil curing agents are effective in solid metal ions in solidified silt,With the increase of curing agent dosage and curing age,The heavy metal ions precipitated in the filtrate gradually decrease,Finally,the amount of heavy metal precipitation gradually stabilizes.The precipitation of heavy metals ion Pb²⁺,Cr³⁺and Zn²⁺did not exceed the limit of hazardous waste specified,Used as roadbed filler will not cause secondary pollution of surrounding soil.