Simulation Of Hydration And Microstructure Formation Of Composite Cement And Electrochemical Verification

The research of early age cement concrete can not only predict the change of microstructure strength of cement concrete during the hydration process,but also predict the strength and service performance of cement concrete structure.However,the hydration variability and complexity of cement and mineral admixtures lead to difficulties in research.With the development of science and technology,there are some new techniques to measure cement hydration,and computer can be used to simulate cement hydration and its microstructure change.Therefore,on the basis of previous studies,it is necessary to study cement hydration,microstructure changes and macroscopic physical properties,explore the electrical properties of cement,build cement hydration model,and predict the macroscopic physical properties and construction performance of concrete.In order to study these problems,relevant hydration models and experiments was established in this paper.The research contents are as follows:(1)According to the hydration dynamic model of cement and its mineral admixtures,the hydration and growth models of cement and mineral admixtures are established,and the hydration equations considering the growth,diffusion of particles and the interaction between particles are solved.According to the particle size distribution of cement particles and concrete mix ratio,the random particle model of mineral admixture concrete is established.Combined with the hydration dynamic model and the random particle model,a hydration model considering particle contact was established.The hydration degree of cement clinker and mineral admixture in hydration process can be simulated and the content of hydration products can be calculated by using MATLAB software editing model.(2)Using the hydration model of mineral admixture concrete,the variation rule of hydration degree and phase content in the hydration process were analyzed,and the influence of different water-cement ratio and mineral admixture content on hydration degree and phase content of cement and mineral admixture were further analyzed.(3)Using the established hydration model of mineral admixture concrete,combined with the chemical shrinkage and autoshrinkage model,the shrinkage model during cement hydration was established,which could simulate the chemical shrinkage and autoshrinkage of cement clinker in hydration process.(4)The strength test of cement slurry and cement mortar was carried out to analyze the influence of water-cement ratio and mineral admixtures on the compressive strength in the hydration process.The electrochemical impedance spectroscopy(EIS)tests of cement slurry and cement mortar were carried out to analyze the variation of electrochemical parameters with hydration time under different water-cement ratios and different mineral admixtures.The theory of strength estimation under different water-cement ratio and different mineral admixtures were predicted by impedance change rate,which provided additional technical support for nondestructive testing.