Study on electrochemical chloride extraction model of reinforced concrete subjected to freezing and thawing effects
Reinforced concrete structures suffer severe durability damage due to chloride salt attack and freeze-thaw cycles.Electrochemical chloride extraction can effectively solve the problem of corrosion of reinforcing steel produced by chlorine salt erosion,but its electrochemical chloride extraction mechanism was affected by freeze-thaw damage to concrete in salt-frozen areas.The electrochemical chloride extraction test was carried out on the freeze-thaw damaged concrete mixed with chlorine salt to establish the degree of freeze-thaw damage of concrete based on the relative dynamic elastic modulus,to study the mechanism of electrochemical chloride extraction of reinforced concrete after freeze-thaw cycling,and to establish a model for evaluating the efficiency of electrochemical chloride extraction of freeze-thaw damaged concrete.The results show that fly ash concrete has greater freeze-thaw damage and lower average electrochemical chloride extraction efficiency in the freeze-thaw environment compared to ordinary concrete.Concrete freeze-thaw damage increased with the number of freezes and thaws and with the amount of fly ash added,and the average concrete electrochemical chloride extraction efficiency increased with the increase of freeze-thaw damage and time.The average chlorine extraction efficiency of concrete with freeze-thaw damage is shorter than that of concrete without freeze-thaw damage,and the time required to achieve the passivation target is shorter.A model for electrochemical chlorine extraction of freeze-thaw damaged concrete was developed based on the degree of concrete damage,and the experimental values fitted well with the model.