Carbonization And Chlorine Ion Erosion Test And Theoretical Analysis Of Steamed Prestressed Concrete

At present, beams of domestic railway bridge mostly adopt steam curing prestressed concrete box girders, but complicated engineering environment is seriously threatened to the durability of the high speed railway bridge structure. The various factors including carbonation, chloride ion, sulfate erosion and improper operation of process of steam curing, construction and maintenance etc. significantly reduced the life of many major bridges engineering structure. Using steam curing prestressed bridges as the research object, by carbonization and haloid ions erosion research, this article studies forecasting model of rules and the carbide chloride erosion under stressing state. Specific content as follows:1. Through the carbonization test, this article studies the relationship among carbonization speed, stress state and carbonization time of steamed prestressed concrete, analyses the main influence factors and carbonization mechanism of steamed prestressed concrete, proposes the multi-coefficient carbonation depth forecasting model of steamed prestressed concrete, and uses the model to obtain got theoretical value of carbonation depth, and compares with the test results.2. Through the experimental research, this article studies the relationship among the content of chlorine ion, erosion time and the depth changes of steaming prestressed concrete, studies chlorine ion in the source, invading way, transmission and penetration mechanism of steamed prestressed concrete, proposes chlorine ion diffusion model under tensile and compressive stress state of steamed prestressed concrete, and uses the test data to validate the model.3. Using the chloride diffusion model of steamed prestressed concrete, this article studies the corrosion initiation time t0of steel strand under the conditions of the1.5km off the coast in the concrete structure in different stress and different cover thickness. The results show that the corrosion initiation time under the action of tensile stress is shorter than that under the action of compressive stress. Under the same conditions, the corrosion initiation time of steamed prestressed concrete is shorter than common concrete.