Mathematical modeling of the colmatation of concrete pores during corrosion

Building Materials

Pore colmatation plays a positive role, since the decrease in the permeability of cement concrete due to the deposition of insoluble corrosion products in the pores leads to a slowdown in corrosion processes. The mathematical model of concrete pore colmatation based on the mass transfer equations is given, which allows to estimate the depth of corrosion damage of concretes in media of various degrees of aggressiveness. The presented model describes the rate of advance of the deposition zone of corrosion products depending on the conditions of the corrosion process. Mathematical models of the kinetics and dynamics of mass transfer accompanied by a decrease in permeability during chemical corrosion of cement stone are presented. Equations are obtained for determining the rate of advancement of the colmatation zone and the thickness of the colmatant layer during concrete corrosion. The dependence of the rate of clogging of pores and capillaries and the thickness of the sediment layer on the change in mass transfer characteristics, taking into account the porosity of the bedding layer, is shown. Graphic dependences of the rate of advancement of the colmatage zone and the thickness of the layer of corrosion products are obtained at the established porosity of the layer for cases of linear and exponential changes in the mass diffusivity coefficient over time. The obtained graphic dependences show that the intensity of the colmatation process decreases, and also illustrate a significant decrease in the intensity of the process with a slight decrease in the porosity of the sediment layer.