Modeling deterioration of cementitious materials exposed to calcium leaching in non-isothermal conditions

摘要

The paper presents a new mathematical model of hydro-thermo-chemo-mechanical behavior of cementitious materials exposed to contact with the deionized water. For analyzing the calcium leaching process, an equation describing kinetics of the process is used instead of an equilibrium curve commonly used in previous isothermal models. This allows taking directly into account the temperature dependence of characteristic times of calcium leaching from different components of concrete what affects the process kinetics, especially that with a relatively fast decrease of the concentration of calcium in pore water. Constitutive relationships describing the transport and strength properties of concrete during chemical degradation at non-isothermal conditions are discussed. The governing equations of the model and boundary conditions are expressed in terms of the state variables: gas pressure, capillary pressure, temperature, calcium concentration and displacement vector. Numerical solution of the model equations with the Finite Element Method, as well as several examples of application of the model for analysis of some test problems, are presented.