Study Of Similarity On Simulation Experiment Considering Chloride Ion Corrosion In Cement-Based Material Under The Tidal Zone

The durability of concrete structures is one of the important issues which draw the public concern in the field of engineering. Previous studies have demonstrated that the chloride ion corrosion is one of most significant influencing factors contributing to the durability of concrete structures. The steel bars embedded in the concrete corrode under the condition of chloride penetration, which subsequently leading to the security and applicability of the engineering structures degraded finally, that is the degeneration in durability of the structures.What’s worse, it bings out some serious engineering accidents.The affection of chloride ingression is much more mainifest in the dry-wet cycling regions according to some related studies.On the basis of some present researches, this paper is illustrated and based on the background of chlorine salt erosion environment in the costal tidal zone. A series of field exposure tests and laboratory simulation tests are designed and completed in this paper. Based on the methods of experimental research and theoretical analysis, in combination with similarity theories, the results of these two kinds of tests are analyzed in the aspect of simulation. The main contents and conclusions of this paper are summarized as follows:1. Under the condition of chlorine salt erosion environment in the costal tidal zone, a series of field exposure experiments involving the concrete and motor are carried out and fulfilled. According to results of the field exposure experiments, the influence of water cement ratio, admixture and exposure time on the main chloride ion ingression parameters involving peak concentration, the depth of convection area and diffusion coefficient are discussed in this paper.2. By simulating the chloride erosion process in the cement-based material (concrete and motor) under the condition of chlorine salt erosion environment in the costal tidal zone, a serial of laboratory simulation tests are designed and completed. In the laboratory simulation environment, the influence of water cement ratio, admixture, erosional time and time rate of dry-wet circulation on the main chloride ingression parameters (concentration distribution of free chlorine ion and diffusion coefficient) are concluded in this paper.3. To start with the classic similarity theories, the similarity of environment between the field tests and laboratory simulation tests is analyzed. According to the comparative analysis of the results obtained from the field tests and laboratory simulation tests, the similarity of the following factors involving two sorts of experimental environment are analyzed:the distribution characteristics of free chlorine ion (mainly including the peak concentration and the depth of convection area), the diffusion coefficient, and the time-dependent attenuation rule of diffusion coefficient and the similarity criterion equation describing the process of chloride ion corrosion. The similar analysis results of the above factors are synthesized, from which a conclusion should be drawn as follows:in the environment of laboratory simulation tests described in the paper, the corrosion behavior of chloride ion in concrete and motor species under immersion and dry-wet cycle of two days has a preferable similarity comparaed with the corrosion behavior in the field tests. The conclusions of this paper can act as some references for the durability experimental design of cement-based material under the condition of dry-wet cycle.