Silty Clay And Lime-soil Electrochenmical Impedance Spectroscopy Characteristics Test Research

Through indoor test, reveals the silty clay and lime soil electrochemical impedance spectrum(EIS) characteristics in different electrode pressure and different electrode area; the relation between silty clay and lime soil electrochemical impedance spectrum characteristics and the equivlent circuit parameters with its physical and mechanical properties were studied.Contact resistance and electrode characteristics influenced greatly on EIS test. With the increase of electrode pressure, the decrease of the electrode area,the tested impedance spectrum tends to a stable state. When EIS present un-Randles model, with the increase of pressure between the electrode, the decrease of electrode area, its equivalent circuit parameters of solution resistance, the charge transfer resistance is reduced, the electric double layer capacitor in increasing, material of contact resistance with the electrode pressure and electrode area is inversely proportional, establish the relationship between material impedance rate and contact resistance.EIS of silty clay with different compactive effort, water content and Na Cl content of pore water. It can be concluded that the EIS presents a quasi Randles model when the silty clay water quality content equal to 9%. However, the EIS presents a un-Randles model, attributing to the diffusion impedance of silty claydisappeared with the increasing of water quality content and NaCl quality content of pore water. Through fitting the equivalent circuit, the condition and characteristics of pore water can be characterized by the solution resistance of its parameters, and the connectivity features for silty clay pore can be characterized by charge transfer resistance. Moreover, the double layer capacitance represents the comprehensive characteristics for inside pores ion concentration of silty clay,while the diffusion impedance can reflect the density of silty clay.Based on the different age of lime soil EIS test, can acquire Nyquist diagram and Bode diagram, the corresponding equivalent circuit was used to simulate its EIS and its parameters are obtained; combined with lime-soil analysis of the internal reaction mechanism, analyzes the changing process of its parameters and the relation of the parameters with corresponding ages of lime-soil shearing strength index. The test results show that lime-soil hardening process can be divided into early and relative stability; its EIS in early present quasi Randles model, in the relative stability present non-Randles model;through the equivalent circuit simulation, it is concluded that the parameters of the circuit: the lime-soil solution resistance Rs, the lime-soil internal electric double layer CPE-T, the charge transfer resistance Rt and the diffusion impedance ZW which presents only in the early. As the growth of the age, Rs, Rt,ZW in increasing, CPE-T in decreasing; acquire the relationship between lime soil shear strength indexes and its equivalent circuit parameters.Comprehensive EIS characteristics of silty clay and lime soil, from theequivalent circuit parameters significance analysis: in the electrochemical system, solution resistance mainly manifested moisture content and pore water solution concentration and its resistance; the charge transfer resistance point on ion concentration, pore connectivity, saturation and the ability of its transfer charge; electric double layer capacitor aim at own diffusion layer capacitance and charge level, with ion charge level and its concentration and pore rate have inseparable relationship; diffusion impedance only when quasi Randles model,focused on the permeability of system, has a direct relationship with ion distribution uniformity.