Research On Concrete Carbonation Depth Model And Its Influencing Factors

The durability of the concrete structure is becoming increasingly highlighted, and the problem is getting more attention. The concrete carbonation is an important branch of durability research. The structural damage caused by carbonation is incalculable. Concrete carbonation refers to the acidic gases such as carbon dioxide from the air may react with the carbide in the concrete, leading to the concrete structure's change. It will affect the function of the protective layer, bring serious security problem to the structure. Therefore, concrete carbonation has always been the research priorities.Based on Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete, carrying on the concrete carbonation test to research the main factors—cement content, water-cement ratio, fly-ash content, temperature, relative humidity and the relationship between concrete carbonation and these factors.The results show that if only consider the concrete itself, the larger water-cement ratio and fly-ash content is, the more easily concrete carbonizes. Oppositely, increasing cement content will slow concrete carbonation down. When researching the mutual influence of the water-cement ratio and cement content, it reveals that water-cement ratio is dominant. If only consider the environmental factors, the higher the temperature is, the faster concrete carbonizes. The larger the relative humidity is, the more slowly concrete carbonizes.On the basis of previous studies, with the result of concrete carbonation test, calculate the carbonation influence coefficient of these factors and set up concrete carbonation depth prediction model considering the factors of cement content, water-cement ratio, fly-ash content, environmental temperature and relative humidity. By analyzing the similarity of concrete carbonation process and the heat conduction problem, ANSYS thermal analysis module is proved to study the concrete carbonation. It shows a new method to research concrete carbonation. Thus, through the parameter transformation, establish the model with the finite element analysis software ANSYS thermal module. Put forward reasonable assumptions, carry on the numerical simulation of concrete carbonation process. Verify the concrete carbonation model with the example and numerical simulation results. The models established only by single factors have limitations. They are not considered completely. The existing prediction models involved environmental factors are less. This established carbonation model considers the influence of environmental factors. It is enough to know the local average temperature and humidity. The model is more practical.