Review article

The paper examines the mechanism of temperature-moisture gradient formation in the contact zone between a carbonated concrete substrate and a repair layer under forced electrode heating. The experimental program included the preparation of sand concrete specimens of strength class B35, accelerated carbonation, and subsequent electro-contact heating with continuous monitoring of temperature and electrical resistance over time. The results demonstrate that forced heating leads to the formation of a non-stationary temperature field accompanied by moisture redistribution and changes in the electro-physical properties of the material. Temperature increase results in a rise in the partial pressure of water vapor, which generates the driving force for directed moisture transport within the capillary-porous structure. There has been developed a mathematical model of non- stationary heat and mass transfer accounting for Joule heat generation and diffusive moisture transport. Comparison of the numerical and experimental results shows satisfactory agreement: the coefficient of determination ranges from 0.90 to 0.98, while the relative error does not exceed 6 %. It is demonstrated that forced electric heating can be considered as a factor of mass transfer intensification and formation of favorable conditions of repair compound adhesion to carbonized base.