The Durability Study And Life Prediction Of Concrete Under The Carbonization And Multiple Factors

With the rapid development of modern technology,concrete has long been the widely used material in the civil engineering industry,in the development of the modern civil engineering industry,concrete structures have also been continuously improving and innovating compared to before,and their strength has also been continuously improving.However,while the strength of concrete continues to improve,the durability deterioration of concrete structures has become a focus of attention in the civil engineering industry.The most essential reason for the durability deterioration of concrete structures is the corrosion and damage of steel bars,and in general atmospheric environments,Carbon dioxide is the main factor causing corrosion and damage to steel bars,so the study of carbonation in concrete structures is of great significance.At the same time,in practical engineering,concrete structures serve under the combined action of multiple factors.Therefore,the main research content of this article is as follows:Firstly,based on the basic theory of concrete carbonization,this article provides a mathematical model for concrete carbonization,and simulates it using COMSOL software to observe the changes in p H value of concrete before and after carbonization.At the same time,due to the neglect of the physical and chemical interactions between pore solutions and hydration products in concrete before and after carbonization in the transport model,a thermodynamic model for the physical and chemical interactions between pore solutions and hydration products is established,obtain the variation pattern of hydration products inside concrete after carbonization.Secondly,this article considers the impact of carbonation and chloride ion coupling on the durability of concrete.For concrete,carbonation and chloride ions interact and influence each other.On the one hand,carbonation affects the binding and transport of chloride ions,and on the other hand,chloride ions affect the p H value of concrete before and after carbonation.Therefore,a carbonation and chloride ion coupling model was established,and simulation and validation were conducted using COMSOL software.At the same time,the physical and chemical interaction between pore solution and hydration products in concrete under the combined action of carbonization and chloride ions is studied by using the Control variate method through the thermodynamic model,and the specific change law curve is obtained.Finally,based on the carbonation life criterion of concrete,this article starts with the theoretical model of concrete carbonation depth,and simulates and analyzes the service life of concrete under single carbonation and multi factor coupling effects.At the same time,in order to better understand the trend of changes in concrete life under different factors,this article simulates and predicts the carbon dioxide concentration(about 500 times the actual concentration)under accelerated carbonation environment.