Using Durability Assessment Of R.C. Structures And Its Engineering Appliance

The carbonation of concrete and corrosion of steel embedded in concrete are important factors affecting the durability of R. C. structures .The time when steel initiates to corrode and the time when concrete cover begins to crack due to corrosion are two important problems of durability assessment of concrete structures. Firstly, by analyzing existing models of predicting concrete carbonation and its influencing factors, a practical model of predicting the depth of carbonated concrete is proposed in this thesis, which takes the compressive strength of concrete as the main parameter and considers influence of temperature and moisture of environment, construction factors, stress condition and density of CO2 in the environment, and plenty of spot-data has been used to verify the model; By means of regression analysis of the spot-data, the calculating model of uncarbonated remainder is formulated; Considering the randomness of concrete carbonation, the paper put forward a probability analysis method of concrete carbonation span-life. Secondly, based on the results of experiments as well as investigations of practical engineering, the paper built the model of predicting the depth of steel corrosion before concrete cover cracks, which considers concrete strength, cover thickness and microenvironment influence; After analyzing results of previous domestic and overseas experiments on corrosion cracking, the paper established the calculating formula of steel corrosion depth when cover cracks and proposed the method of analyzing corrosion cracking span-life based on the reliability theory. Finally, applying the model of predicting carbonated concrete, the model of predicting depth of steel corrosion and the method of using durability estimation, which are established in the thesis, to the Jiang Xin Water Pump Station of Wuhan Iron & Steel Corporation, the paper analyzed its residualcarbonation span-life and residual corrosion cracking span-life on the basis of its durability investigation, which provides foundations to the decision of its maintenance, strengthening and daily managements.