Electrochemical Impedance Spectroscopy Study Of Hydration Process Of Cement-based Material

Cement-based materials such as concrete are extremely widely used in modern buildings and their roles are irreplaceable.The hydration process is a complex process including physical changes and chemical reactions,and the hydration process is closely related to the microstructure and mechanical properties.Therefore,the research on the hydration process of cement-based materials is particularly important,and it has always been a hot spot for scientific researchers;In engineering practice,the structural quality inspection must be carried out in accordance with the current regulations promulgated by the country,and the compressive strength of the standard test piece is used to inspect and evaluate the quality.The existing detection methods,including rebound method,ultrasonic method,ultrasonic-rebound integrated method,micro method and model method,have many shortcomings,so better nondestructive method of compressive strength testing is also a hot topic for scholars.In this paper,EIS is used to study the above problems,and an electrochemical impedance spectroscopy study on the hydration process and compressive strength of cement-based materials is carried out.The main research contents and research conclusions are as follows:(1)The hydration process of cement paste and cement mortar are studied,also the relationship between EIS and compressive strength.and a new equivalent circuit model is proposed to analyze the EIS,impedance parameters and seepage in each period of the hydration process.The structural parameters are analyzed;according to the impedance and phase angle in the and the seepage structure parameters obtained according to the EIS the relationship between the EIS and the compressive strength is analyzed,and the relationship between the EIS and the compressive strength is obtained;(2)The hydration process of fly ash-cement composite system,slag-cement composite system,fly ash/slag composite-cement composite system,metakaolin-cement composite system,and the relationship between EIS and compressive strength were carried out.In the study,the characteristics of EIS in the hydration process of each system,the influence of admixtures on the hydration process,and the differences in the influence process and mechanism of each admixture were obtained.The relationship between seepage structure parameters and compressive strength obtained from EIS;(3)the electrochemical impedance spectroscopy method is proposed to test the compressive strength of cement-based materials of cement paste,cement mortar and fly ashcement composite systems The pore structure is used as a bridge Use EIS to explore the pore structure at various hydration ages,and combine the existing models of the relationship between a variety of pore structures and compressive strength to analyze,verify and screen out the most suitable model.The model converts the relevant information of electrochemical impedance spectroscopy to obtain the compressive strength of cement-based materials,and obtains a new continuous and non-destructive testing method for compressive strength.