Basic Research On Durability Of Steel Corrosion

Concrete is the world's indispensable building material, With the development of society, Concrete Technology has been greatly improved, But the durability of concrete is still the basic problem affecting concrete structures。The factors of reducing the durability of concrete structures are mainly:Concrete carbonation,Chloride erosion,Freeze-thaw damage,Alkali-aggregate reaction and Steel corrosion, etc. Steel corrosion is the most important aspect. And a variety of other factors that may lead to steel corrosion. Therefore, this text do a certain studies aim at steel corrosion, the main contents are as follows:(1) Steel-bar corrosion are generally divided into uniform corrosion caused by concrete carbonation and local corrosion caused by chloride erosion. Using the method of structural reliability, in the basis of small samples uniform corrosion which caused by concrete carbonation adopts the form of Gauss distribution and local corrosion caused by chloride erosion adopts the form of peak I distribution, the position parameter and scale parameter of different distribution are determined, The structure's durability is estimated more precisely, so that the problem of small sample of the probability density function estimation is solved.(2) Based on the elastic-plastic mechanics and fracture mechanics theory, the formulas for critical expansion force of reinforced concrete are deduced. The result is analyzed by experimental data and few calculation models which are in common use. The results show that, the critical expansion force of reinforced concrete deduced of the fracture mechanics theory is closer to the true value, however, the critical expansion force of reinforced concrete deduced of the elastic-plastic mechanics is smaller to the true value. Thus, in the research of concrete cracking caused by reinforcement rust expansion, it is better to use the theory of fracture mechanics.(3) In the atmospheric environment, the structural life is generally divided into two parts:the process of concrete carbonation and the process of steel corrosion. This text are based on the formula of Prof Liu, choosing reasonable correlation coefficients, the time of two processes of the structural life is calculated, also that the purpose of predicting structural life is achieved. Structural life prediction will be applied to practical engineering.