Simulation Of Cement Hydration And Prediction Of The Elastic Modulus Of Cement Paste

Cement-based materials are a kind of complicated porous materials and have been widely used in various fields. Therefore, it is of important theoretical significance and practical value to study their macroscopical physical and mechanical properties. Through the computer simulation of cement hydration, the cement paste model is obained. With various numerical methods, the quantitative relationship between the macroscopical physical and mechanical properties and microstructure of cement paste can be established, which will provide a theoretical basis for the optimal performance design of cement-based materials.A fast Fourier transform method is discussed in detail for predicting the elastic modulus of one-dimensional heterogeneous materials. The convergence and precision of the method is analyzed. This method is further extended to the prediction of elastic modulus of two-dimensional porous materials. In comparison with the analytical solution of the elastic modulus of materials with circular pores, the validity of this method is verified. The effects of pore shapes, the arrangement of pores, and the Poisson’s ratio of the solid phase on the elastic modulus of porous materials are evaluated in a quantitative manner.By introducing the Rosin-Rammler cumulative distribution function and the periodic boundary conditions, the initial distribution of cement particles is implemented. According to the principles of hydration kinetics, three concentric circles are used to represent the unhydrated cement, hydration products, and air layer of each cement particle. Interference coefficients are introduced to consider the interactions between cement particles. By comparing the simulated degree of hydration of cement paste with experimental results, the validity of this method is verified. The effects of the water/cement ratio, maximum cement diameter, and temperature on the degree of hydration are evaluated in a quantitative manner.Based on the simulated microstructure of cement paste, a fast Fourier transform method for predicting the elastic modulus of cement paste is discussed. Equidistant pixels are selected the iteration method is used to solve the macroscopical elastic modulus of cement paste. Finally, the validity of the method is verified with the experimental results reported in the literature. The effects of the water-cement ratio, maximum cement diameter, and temperature on the elastic modulus of cement paste are evaluated quantitatively.