Study On Effect Of Electrochemical Chloride Extraction And Frost Resistance After Extraction Of Reinforced Concrete Components

The durability of reinforced concrete structures is not only related to the safety of structures such as building and bridges,but also closely related to social and economic interests.The main reasons for the failure of reinforced concrete structures are as follows: one is the corrosion of reinforcement caused by chloride salt erosion and the other one is concrete damage caused by freeze-thaw cycle in cold regions.Electrochemical chloride extraction(ECE)is a new type of concrete non-destructive repair technology,which can eliminate chloride ions in reinforced concrete structures and restore the passivation of reinforcement without destroying the concrete structure.So ECE has a good application prospect.At present,there are many research results on ECE at home and abroad,but there is no related research results about the effect on the anti-freeze durability of reinforced concrete structures after ECE.Therefore,the chlorine removal effect of ECE and the effect of anti-freeze performance after ECE was studied by experiments,The main research content of this paper including the following:The effects of ECE time,fly ash dosage,water reducer and air entraining agent on ECE efficiency and residual chloride ion content were studied.The longer the ECE time is,the higher the ECE efficiency is;the more the fly ash is added,the lower the ECE efficiency is;the incorporation of the water reducer reduces the ECE efficiency;the incorporation of the air entraining agent improves the efficiency of ECE.After ECE,the chloride ion content in the vicinity of the reinforcement is the least,and the chloride ion is concentrated in the range of15~35 mm from the surface of the specimen.The effect of ECE on the corrosion potential of reinforcement was studied.During the ECE process,the corrosion potential of reinforcement increases in a negative direction.After the end of the ECE,the corrosion potential moves forward and gradually restores the passivation potential.The ECE process was simulated using Finite element software and compared with the test results.The research results show that by establishing an accurate model in the software and determining the boundary conditions,the software simulation results have higher accuracy,and finite element software can be used to predict the ECE effect.Through the rapid freezing and thawing test of concrete,the changes of frost resistance of reinforced concrete structures before and after ECE were compared and analyzed.The results show that for concrete without mineral admixture and admixture,short-term ECE slightly improves the frost resistance of concrete.With the extension of ECE time,the frost resistanceof concrete decreases gradually.The more the fly ash content is,the worse the frost resistance of the concrete is.The ECE process will cause the frost resistance of the fly ash concrete to be greatly degraded;the frost resistance of the concrete after adding the water reducer and the air entraining agent significantly improved,the frost resistance of the structure after ECE did not change much.