The Electromigration Of Sea Sand Chloride Ion In Mortar And Its Effect On Reinforcement Corrosion

Due to the shortage of sand and stone resources in the world,more and more attention has been paid to the development and utilization of sand and stone.Our country has abundant sea sand resources.The development and utilization of them is an important strategy to ensure the rapid development of our country’s economy and construction projects.However,the chloride ions contained in sea sand can cause corrosion of steel bars and cause structural degradation hazards.At present,the sea sand is mainly used by water washing.However,due to the lack of research on the migration of sea sand chloride ions in concrete and the corrosion caused by it,the standard requirements for the chloride ion content in sea sand after washing are different.As a result,the current development and utilization of sea sand is seriously insufficient.At present,sea sand is mainly used by washing and desalinating it.However,due to the lack of research on the migration of sea sand-type chloride ions in concrete and the corrosion caused by it,the standard requirements for the chloride ion content in sea sand after washing are different.This has led to a serious shortage of sea sand development and utilization.In order to be able to use sea sand scientifically and rationally,the first problem that must be solved is to explore the mechanism of the migration of sea sand chloride ions in concrete and the influence on steel corrosion,and based on this,propose technical means to solve the harm of chloride ions in sea sand.In this paper,In this paper,through the applied voltage electromigration test,the electromigration of chloride ions in the mortar and the effect on the corrosion of steel bars under different voltages,different chloride ion introduction methods and different mortar types were studied,and the concentration distribution of chloride ion in the process of electromigration of sea sand type was calculated by COMSOL.The main research contents and conclusions are as follows:(1)Under the same electromigration time,the average migration amount of chloride ions in sea sand is higher than that of normal type doped with chloride ions.Under the voltages of 5 V,10 V,and 15 V,the migration of sea sand chloride ions is 23.8%,38.1%,and 20.9% lower than that of normal chloride ions,respectively.The migration amount of sea sand chloride ion in RPC(reactive powder concrete)is significantly lower than that of ordinary mortar,and the average migration amount is only 5.5%,10.1% and17.9%.With the increase of voltage,the growth rate of the migration rate continues to decrease.And through the similarity theory,the time similarity coefficient of electromigration and natural corrosion is obtained.(2)Sea sand type chloride ion and normal type chloride ion doped have little effect on the initial corrosion potential of steel bars.Under the same electromigration time,the corrosion potential of steel bars in the normal type chloride ion doped specimens is 77%,28%,and 15% greater than that of the sea sand type chloride ion specimens,and the corrosion of steel bars caused by chloride ion in the normal type is stronger than that of the sea sand type.The corrosion rate of sea sand specimens in the initial and stable stages of corrosion is lower than that of the normal type.The difference in polarization resistance between the two is mainly reflected in the initial stage of corrosion.RPC(reactive powder concrete)has stronger anti-corrosion ability than ordinary mortar,and the reduction of corrosion potential after electrification is 31%,62%,46% lower than that of ordinary mortar.(3)The finite element simulation of the migration process of sea-sand-type chloride ions in the mortar under external voltage was carried out by COMSOL.The theoretical value of chloride ion concentration distribution and the experimental data have certain errors,but the overall migration is consistent.