Degradation Of Concrete Properties Under Stray Current Based On Reinforcement Corrosion And Calcium Ion Dissolution

With the rapid development of social economy and cities,the facilities of electric power systems such as rail transit,power stations and substations,which are vital to people’s livelihood,play an increasingly important role in the construction and development of cities.Concrete has become the main raw material for the construction of these facilities because of its good economy,moldability and durability.However,the impact of stray current corrosion generated by the aforementioned power systems on their own concrete structures is a problem that people must face.Most of today’s studies on the degradation of concrete performance under the action of stray currents do not consider the combined effect of reinforcement corrosion and calcium ion dissolution on concrete performance.However,in the stray current environment,the concrete structure in saturated water environment,the reinforcement corrosion and calcium ion dissolution behavior is occurring simultaneously.Therefore,it is of practical importance to study the effect of the joint action of reinforcement corrosion and calcium ion dissolution on the concrete performance in stray current environment.In this paper,the deterioration of concrete properties under the action of stray currents is studied based on the behavior of reinforcement corrosion and calcium ion dissolution in concrete,and the main research contents are as follows:(1)From the theoretical point of view,the effects of reinforcement rust swelling and calcium ion dissolution on the compressive strength of concrete under stray current environment were analyzed,and the theoretical degradation model of concrete compressive strength under the action of reinforcement rust swelling was obtained,and the main factors affecting the change of concrete compressive strength under stray current environment were obtained through summary analysis.(2)The effects of concrete strength grade,reinforcement diameter,voltage magnitude and energizing time on reinforcement rusting,calcium ion dissolution and concrete compressive strength were studied by conducting energizing acceleration tests in a simulated stray current environment.The study showed that the higher the concrete strength grade and the larger the diameter of the reinforcement,the smaller the degree of reinforcement corrosion,calcium ion dissolution and concrete strength loss;the higher the energizing voltage,the more serious the degree of reinforcement corrosion and calcium ion dissolution,and the greater the concrete strength damage;finally,the prediction model of concrete compressive strength under stray current environment was obtained using the test data.(3)Using X-ray diffraction and electron microscope scanning methods,the microstructure of the corroded concrete was studied,which showed that due to the effect of calcium ion dissolution,Ca(OH)2 dissolved inside the concrete after the current corrosion,and the structure became loose.And when the voltage is larger,Ca(OH)2 dissolution and structural loosening is more serious.(4)The interaction between reinforcement corrosion and calcium ion dissolution inside concrete under stray current environment was investigated.The analysis of the measured corrosion current,concrete resistivity,steel corrosion rate and calcium ion dissolution rate showed that there is mutual influence between steel corrosion and calcium ion dissolution.