| Reinforced concrete structure has the advantages of good durability,strong modelability and low maintenance cost.It is the most widely used structural form in the construction industry.Concrete is a porous material,and the chloride ions in the environment can enter it and come into contact with the steel bars.As a result,the steel in the buildings near the shore are prone to corrosion,reducing the carrying capacity of the steel bars.Anti-corrosion coating is economical and efficient,and is an excellent means of corrosion protection.At present,there are epoxy resin coating,hot dip galvanized coating and enamel coating and other anti-corrosion coatings,but these coatings will reduce the adhesion between steel and concrete or corrosion protection performance is poor.Therefore,it is necessary to study a new coating which can enhance the corrosion protection and bond strength of steel bar.In this paper,quartz sand was added to ceramic coating to develop a new coating with good corrosion performance and enhance the bond strength between steel bar and concrete.In this paper,the corrosion behavior of ceramic coated steel bar modified by quartz sand in different environments was studied and analyzed by electrochemical testing methods such as open circuit potential,electrochemical impedance spectroscopy and linear polarization resistance,and the feasibility of corrosion protection of steel bar modified by quartz sand ceramic coating was discussed.The main research work of this paper is as follows:(1)The quartz sand modified enamel coated steel plate was soaked in 3.5wt.% Na Cl solution for 30 days,and the coated steel plate was subjected to electrochemical test periodically.Through the circuit fitting of test results,the corrosion behavior of the coated steel plate in Na Cl solution was obtained.All the results show that the coating to improve the corrosion protection performance of steel plate.With the increase of content of quartz sand,quartz sand of modified enamel coating on steel corrosion increase.When the content of quartz sand exceeds 10%,the addition of quartz sand will reduce the corrosion protection performance of the coating.10% content of quartz sand modified enamel coating corrosion protection performance is the best.The test results prove that the modified quartz sand enamel coating in Na Cl solution has a good corrosion protection performance.(2)The specimens of enamel coated steel bar modified by quartz sand were immersed in simulated concrete pore solution for 30 days to study the corrosion protection performance of coated steel bar under the influence of concrete pore solution.The results show that the enamel coating modified with quartz sand can provide corrosion protection for steel bars,and the corrosion protection performance of the coated steel bar with 10% quartz sand is better than that of other coated steel bars.The test results prove that the enamel coating modified with quartz sand has good corrosion protection performance in the simulated concrete pore solution.(3)In order to study the corrosion protection performance of quartz sand modified enamel coating under real conditions and the influence of the addition of quartz sand on the coating,the reinforced specimens of quartz sand modified enamel coating were wrapped with mortar and soaked in 3.5wt.% Na Cl solution.The results show that the corrosion protection performance of mortar coated steel specimens with 10% quartz sand content is higher than that of other specimens,while 20% and 30% quartz sand content can reduce the corrosion protection performance of the coating.Corrosion current density of uncoated mortar reinforcement is an order of magnitude higher than mortar coating steel specimens.For mortar coating steel specimens,10% quartz sand adding amount of coated steel bar corrosion current density of the specimens is lower than other specimen.The test results prove that the modified quartz sand enamel coating under the parcel of mortar can also be effective for steel to provide corrosion protection. |
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