Research On Durability Of Metal Joint In Reinforced Concrete Structure Exposed To Marine Environment

Reinforced concrete structures have been widely used, for Reinforced Concrete structures can make the best use of both concrete and steel bars. But the durability of concrete structures is not satisfied due to various causes, large-tonnage reinforced concrete structure were less than the life expectation; especially in marine environment, Where is high air humidity and contains lots of chloride. The chloride can accelerate the corrosion rate of steel bar that cause structure lose durability and safty. Today, the durabilty has became a wordwide problem and people pay more attention to it. Several problems of the durability of Metal Joint in Reinforced Concrete structures Exposed to marine envirorunent have been studied in this paper, including the process of electrochemical corrosion, corrosion forms and corrosion products. Several anticorrosion treatment of metal joint were tested as well.The main content of the paper is as follows:(1) In this paper, we determinated the change of chloride concentration pre-and post flood at the same sea area by X-mate Pro Portable multi-parameter determinator, the results of experiment show that the chloride concentration chlorinity influenced by tide.(2) Some experiments have been done to research the corrosion rate of metallic building material in various environments. It is found that the corrosion rate of metal where at the junction of air and sea is the fastest, it also directly affected by both of the chloride concentration and the dissolved oxygen concentration. Research by microscope and spectrophotometer show that the corrosive products have the same component, which come from laboratory and coastal region. But the corrosion forms and physical property have slight difference from each other.(3) Relative potential have been determinated by FLUKE digital multimeter with several different forms of bar splice, and contrastively analysed. The result show that the macrocell corrosion has been generated by component difference of steel reinforcement. Moreover, Different forms of bar splice has an important effect on the macrocell corrosion.(4) Two methods have been attempted for protect the external metal, including motar top and sacrificial anode. Measures for metal-anticorrosion at present are summarized, which will be used as guide to desigh of durability for external metal joint.