Study On Non-Uniform Deterioration Of Durability And Prevention Of Concrete After Electrochemical Restoration

The corrosion of steel bar caused by the erosion of chlorine salt is the main culprit of the destruction of concrete structure in durability.Electrochemical restoration technology which is based on electrochemical principle is an important means to improve the durability of concrete structures.There is an non-uniform phenomenon of electrical migration in the process of electrochemical restoration of concrete,and the effect of nonuniform electrical migration on the deterioration characteristics of concrete after restoration still needs further study.In this paper,by means of laboratory tests,the influence of the non-uniform electrical migration of concrete on the degradation characteristics was studied.At the same time,the control experiment of heterogeneous electrical impact is carried out based on Bidirectional electrical migration rehabilitation(BIEM)and external anticorrosive coating.The COMSOL Multiphysics software was used to simulate the internal potential and chloride ion distribution characteristics.The method of homogenization electrical migration was investigated by means of simulation,and the experiment of homogenization electrical migration test of concrete electrochemical restoration was carried out to verify the validity of the method.The main research contents of this article are as follow.(1)Three stages which include accelerating erosion,electrochemical restoration and accelerating degradation of indoor artificial simulation are involved in the process of design and maintenance.And the artificial simulation of concrete structure in reality also consists of three stages: initial chloride ion erosion,electrochemical restoration,deterioration and re-erosion.Two groups of test variables with different degrees of durability damage and different bar spacing were set up to conduct the experiment of electrochemical restoration non-uniform electrical migration effects.By tracking the concentration of chloride ions and the corrosion potential of steel bars in different stages of concrete degradation after the electrochemical detection,the effects of non-uniform electrical migration on the spatial distribution of chloride ions and the corrosion potential of the steel bars during non-uniform deterioration of concrete were investigated.(2)In order to control the effect of non-uniform electrical migration on the distribution of chloride ions and the corrosion potential of steel bars during the process of concrete deterioration,it starts from the perspective of preventing external ion intrusion and corrosion protection of steel bars.Being Based on external anti-corrosion coating and BIEM technology,the experiment of non-uniform electrical migration impact controlling was conducted to explore preventive measures for non-uniform degradation.The effect of BIEM on the corrosion potential of steel bar in the process of concrete degradation after electrochemical restoration was investigated by means of laboratory tests.At the same time,this research also in accordance with the engineering example to conduct core drilling sampling on the electrochemical restoration pier in the actual project and carry out anti-corrosion treatment on the surface of the core sample.The treated core sample was subjected to an accelerated deterioration test which is indoor high-low temperature cycle.The degradation characteristics of the coating on the surface of the core sample,the depth and extent of the chloride ion attack,and the distribution of chloride ions inside the core sample were studied to compare them under different working conditions.(3)This study uses COMSOL Multiphysic software to establish a numerical model for the non-uniform electrical migration of concrete electrochemical restoration.The numerical model was used to make numerical simulation of the internal potential and chloride ion transmission in the process of non-uniform electrical migration of pre-doped chlorine salt specimens.Being based on the method of simulation,the way of making concrete homogeneous electrical migration was investigated by changing the anode position,setting different regions of the electrical migration surface and different voltage,etc.Meanwhile,the experiment was carried out to verify the validity of the homogenization electrical migration method.