Study On Carbonization And Chlorine Ion Penetration Corrosion Regularity Of Coastal Concrete Bridge Under Load In Service

At present, the durability problem of reinforced concrete bridge structure is increasingly become the focus in the world today. In the process of operation, reinforced concrete bridge not only bears the long-term effect of load, but also experiences the threat of environment, such as the carbonization, chloride ion, freeze-thaw, sulphate erosion etc. Concrete structure materials under the dual effects of load and environment will cause damages and aging, especially for the bridge structure in the coastal environment, because of the complexity of the Marine environment, the concrete structure is very easy to appear performance degradation, bearing capacity and durability decline. Therefore, the research on the properties of concrete structures under load is of vital importance to the proper design and analysis of the above structures.This paper is supported by shandong natural science fund (2009ZRB019HD)" mechanism research based on mechanical damage to the durability of marine concrete ", and related research about carbonization and chlorine ion corrosion under different loads is done. Through exerting long-term and short-term the two forms of axial load, the content of CaCO₃ and chlorine ion in concrete can be determined. This paper also analyses the regularity of concrete durability under load, and according to the relevant parameters got in experiment, the life of bridge structure durability can be forecasted.Test results show that under axial tensile load, the durability of concrete will decrease with the increase of load level and the water-binder ratio; When concrete is in long-term axial tensile load, its durability performance is lower than short-term axial load and unloaded conditions. When concrete is under long-term axial compressive load, its durability performance appears certain regularity according to the difference of the load leval: Stress levels for 0.35 specimens, carbonation depth or the content of chlorine ion are less than the unloading; when the compressive stress level is 0.75, the carbonation depth or the content of chlorine ion are more than unloading, When the compressive stress level is between 0.35 and 0.75, due to the instability of the aggregate concrete and the interface cracks, the action of concrete durability has certain degree in this compressive stress level. Comparing the two kinds of loads, a conclude can be reached: for the same proportion of concrete, under the same load stress level, the durability quality under axial tensile load is lower than that under axial compressive load. It is clear that the form of load has a big effect on the durability quality. Finally, according to the related parameters, the life of binhai road in the city of Qingdao is forcasted, the conclude is: carbonation is less affected for the concrete, and chloride erosion is the main reason for durability.