PREDICTING THE DURABILITY OF CONCRETE STRUCTURES WITH REGARD TO MASS TRANSFER AND PORE COLMATATIONS DURING CORROSION

Abstract

The object of research is the corrosion process of destruction of concrete and reinforced concrete structures in aggressive media. The purpose of the investigation is to establish a set of relationships and ratio between the characteristics of this process and various external and internal factors that affect the growth of corrosion. To solve the tasks set on the basis of the obtained experimental data, the method of mathematical modeling of corrosion processes was applied. The theories of physical and chemical transformations and heat and mass transfer laws suggest that different stages of corrosion can be simulated by differential equations of interrelated heat and mass transfer with boundary conditions. They are defined by arbitrary functions of initial transfer potentials and nonlinear boundary conditions of all known types. The possibilities of developed physical and mathematical models of mass transfer in the processes of studying corrosion of various types are demonstrated. They allow to evaluate the concentration of the transported component throughout the thickness of the concrete structure and in the biofilm itself at any time, as well as the concentration of "free" calcium hydroxide in the liquid phase. As a result, it is succeeded to predict the durability and reliability of concrete structures with a minimum error. The proposed author's model of the destruction of cement concretes, taking into account the colmatation of pores and capillaries, ensures the adequacy of judgments about the kinetics of mass transfer processes during corrosion of the II type.