Dynamic Electrochemical Model of Steel Corrosion in Concrete Microenvironment under Multifield Action of Heat-Moisture-Chlorine

Abstract

This study utilized a heat-moisture coupling model to characterize the internal microenvironment of concrete and establish the relationship between environmental temperature, humidity, external chloride ions, corrosion potential, corrosion current density, and rust layer thickness distribution on steel surface. The model enables dynamic characterization of steel depassivation, corrosion propagation, and rust layer expansion under natural climate environments. The development of temperature, humidity, chloride ions concentration, and corrosion current density in concrete under a time-varying environment was verified by experiment and the data obtained from literature. The research results show that taking heat-moisture coupling into account is necessary in steel corrosion modeling. Temperature and humidity are nonuniformly distributed in concrete leading to nonuniform distribution of chloride ions diffusivity. The growth rate of chloride ions concentration responds to environment temperature change more rapidly than humidity change. Under a time-varying environment, corrosion current density may increase briefly due to the increase of environment temperature and humidity.