Research On The Effect Of Load And Saturation On Oxygen Diffusion And Steel Corrosion In Coral Concrete

The deterioration of concrete structures is closely related to the transmission process of harmful substances such as moisture,oxygen,and chloride ions in the environment.The influence of oxygen and moisture on the rate of steel reinforcement corrosion in concrete is particularly significant.However,in practical engineering,concrete structures are subject to different loads and work in environments with varying air humidity,resulting in different levels of water saturation inside the structure.The coupling effect of these two factors has a detrimental impact on the diffusion of oxygen and the corrosion of steel reinforcement in concrete structures.Therefore,this thesis improves the oxygen diffusion measurement device,determines the influence of sustained load and different water saturation levels on the oxygen diffusion rate of coral concrete,calculates the oxygen diffusion coefficient of coral concrete based on experimental data,and analyzes the impact of sustained load and different saturation levels on the oxygen diffusion in coral concrete.Using the obtained oxygen diffusion coefficient,a coral concrete oxygen diffusion coefficient model is established under different conditions using COMSOL Multiphysics numerical simulation software,which simulates and analyzes the oxygen diffusion process in coral concrete.The simulation data is then compared with the experimental data to verify the accuracy of the established oxygen diffusion model.Finally,the free chloride ion concentration inside the coral concrete specimens is measured,and the corrosion current density of steel reinforcement inside the coral concrete under different oxygen concentrations and environmental humidity levels is determined using the polarization resistance method.The thesis concludes with an analysis of the impact of oxygen concentration and environmental humidity on the corrosion of steel reinforcement inside coral concrete.The main research contents of this thesis are as follows:(1)Concrete test blocks of C30 coral concrete were cast,and the compressive strength values were measured using a pressure testing machine.This provided the basis for subsequent experiments in which a sustained load was applied to determine the effect on the oxygen diffusion of coral concrete.(2)Improved the apparatus for measuring the concrete oxygen diffusion coefficient and calculated the oxygen diffusion coefficient of coral concrete under different sustained load intensities and different water saturation levels through experiments using the improved device.Analyzed the impact of sustained load intensity and water saturation level on the oxygen diffusion in coral concrete.Compared the oxygen diffusion coefficient of coral concrete with that of ordinary concrete,and analyzed the reasons for the difference in oxygen diffusion coefficient between coral concrete and ordinary concrete.(3)Using the oxygen diffusion coefficient of coral concrete obtained from experiments,the internal oxygen transport process in coral concrete under different sustained loads and water saturation levels was simulated using COMSOL Multiphysics software.The oxygen transport laws inside the coral concrete and the influence of load and water saturation on the oxygen diffusion in coral concrete,as well as the diffusion mechanism,were analyzed.The simulation data was compared and validated against the oxygen diffusion data obtained from experiments,which demonstrated the accuracy of the coral concrete oxygen diffusion model.(4)Casting coral concrete test blocks with steel bars and determining the free chloride ion concentration inside the coral concrete test blocks through experiments.An artificial oxygen environment box was designed to change the oxygen concentration and environmental humidity inside,and the corrosion current density of steel bars in the coral concrete test blocks cured for 6 months under different oxygen concentrations and environmental humidity was measured using the polarization resistance method.The influence of oxygen concentration and environmental humidity on the corrosion rate of steel bars in coral concrete was analyzed,and the impact laws of oxygen concentration and environmental humidity on steel bar corrosion were summarized.