Molecular Dynamics Study On The Structure And Properties Of Cementitious Material Hydration Products

Calcium silicate hydrate is an amorphous material which generated by hydration of C3 S and C2 S, and it is also one of the main hydration products of Portland cement,which accounts for two-thirds of the cement hydration products, and is a major source of reinforcement properties of cement, concrete and other cement-based materials.Besides, it is also the main source of some macro properties of cement-based materials,includinghardening, shrinkage, sticking. Due to various hydration products of cement, it is impossible to extract calcium silicate hydrate for analysis,, so many scholars have tried to use different methods to synthesis of calcium silicate hydrate and use computer simulation method to study and explore the microscopic structure of calcium silicate hydrates.This paper synthesizes calcium silicate hydrate based on different calcium silicon ratio, temperature and time, respectively by using hydrothermal synthesis method, and studied influence of different synthesis conditions on phase, microstructure and polymerization degree of the calcium silicate hydrate..Results showed that with increasing of calcium silicon ratio, temperature and time, different minerals such as tobermorite, xonotlite and Truscottite gradually occur, and the surface of synthesized calcium silicate hydrate tend to become compact.Calcium silicate hydrate mainly takes its [SiO4]4- combination state for characterization, with increasing of temperature,, the peak of Q1 and Q2 moved towards high wavenumbers, so the degree of polymerization increases with temperature. And with the increase of calcium silicon ratio and reaction time, can reduce calcium silicate hydrated polymerization degree.Because the complex structure and species diversity of calcium silicate hydrate, inthis paper, we applied advanced means of computer simulation to simulate tobermorite structure as initial structureaccording to Taylor hypothesis, and discussed the modules,cell size and mechanical properties applicable to the calcium silicate hydrate,We established 11 ?tobermorite structure as the initial model in Material Studio software,and applied the force field of two different modules to optimize the initial structure.According to the energy balance analysis, crystal cell parameters and mechanical properties, it is believed that 11 ?tobermorite can be used as the structure of the amorphous calcium silicate hydrate initial structure, and the selected force field in two modules both have ideal results, application of Forcite module can make the initial structure balance faster.Since calcium silicate hydrate is amorphous structure, annealing process of heat treatment process was applied for simulation and amorphous calcium silicate hydrate was obtained.