Physical and mathematical modelling of the mass transfer process in heterogeneous systems under corrosion destruction of reinforced concrete structures

摘要

The article presents the equations of "free calcium hydroxide" mass transfer describing the liquid corrosion of cement concretes. The boundary value problem of "free calcium hydroxide" mass conductivity in dimensionless variables is obtained. Also, in order to obtain a solution to the boundary value problem of mass conductivity, it is proposed to use a combined approach, which consists in the fact that at the beginning of each microprocess an analytical solution is obtained, and then the whole process is gradually calculated on a computer. It should be noted that the method gives good results if it is carried out in conjunction with the Laplace integral transformation method. In addition, the Laplace transform often makes it possible to obtain a solution in two forms: at Fom >0,1 and Fom0,l, this is the advantage of using this transformation. The solution of the boundary value problem of mass conductivity is obtained, which allows to find not only the profiles of dimensionless and dimensional concentrations of "free calcium hydroxide" in concrete thickness, but also makes it possible to determine the value of this value gradient at the phases interface. The obtained solution allows further determining the time of reaching the critical concentration of "free calcium hydroxide" at the phases interface, corresponding to the beginning of high-basic components decomposition, and hence moving on to the further stages of study and corrosion processes modeling, which is confirmed by the graphical dependencies presented in the paper.