Research On Solidified Materials Mix Proportion And Solidification Mechanism Of Urban Lake’s Dredging Silt

Every year there is a large quantity of dredging silt which pollute the environment and can be solidified into good quality soil for waste reuse.Silt has a certain activity,complicated composition and high clay content,making issues like the solidification mechanism and efficient solidified materials mix proportion remain to be further researched.Taking dredging silt in Wuhan East Lake as the research object,electrical resistivity test,Nuclear Magnetic Resonance test and unconfined compressive strength test are carried out to reveal the silt macroscopic and microscopic solidification mechanism and explore efficient solidified materials mix proportion aiming at super saturated silt.The main research contents and conclusions are as follows:1.The macroscopic solidification mechanism based on the time response of resistivity.The electrical resistivity of solidified soil are measured within 72 h in a non-contacting electrical resistivity measurement device and the influence of curing age,cement content and organic matter content on the resistivity of solidified soil are analyzed.According to the characteristics points of the resistivity curve physical and chemical reaction process of silt solidification is divided into I dissolving period,II induction forming period,III hardening period,and the macroscopic solidification mechanism based on the time response of resistivity is analyzed.2.The microcosmic solidification mechanism based on the transformation of pore water.The nuclear magnetic signal amplitude-T2 curve of solidified soil is obtained by Nuclear Magnetic Resonance test,and the influence of curing age,cement content and initial moisture content of silt on the content and distribution of pore water in solidified soil are analyzed.And the microcosmic solidification mechanism based on the transformation of pore water is discussed preliminarily.As the growth of the curing age,the increase of cement content and the decrease of initial moisture content,the scope of T2 distribution of solidified soil is narrowed,relaxation peak gradually moving to the left,pore water distributing in the small pore.And the relaxation peak areas decreases gradually at the same time,meanwhile the content of pore water decreases.Besides,the main effect of curing age is to reduce the moisture content in the big pore,but cement is not only beneficial to reduce the pore water content in the big pore,but also to reduce the pore water content in the small pore.3.Solidified materials mix proportion aiming at super saturated silt.On the basis of cement solidified dredging silt,admixtures is added to analyze of the solidification effect and best dosage of fly ash,lime and super absorbent polymer.And the best proportion of solidified materials is worked out by orthogonal test of four kinds of material,offering reference to the practical engineering of low content of cement to deal with super saturated dredging silt.