Researchon Chloride Binding Problem And Life Prediction Of Concrete

In this paper,the traditional diffusion model of Fick has been studied and the fitting relationship between bindingisotherm and chloride binding capacityhas been analyzedafter considering the effects of chloridebinding.Thenthe influence of chloride binding capacity on the transport process has been studied by numerical simulation.Finally the durability failure probability of the concrete structure has been calculated which based on the reliabilitymethod of concrete durability prediction by using the Monte-Carlo algorithm.The main contents of this paper are as follows:(1)The results and status of theresearches on chloride penetrating in concrete at home and abroad has been reviewed and summarized.The chloride transport mechanism has been analyzed,which includes thetransport mechanisms,occurrenceconditions and equations of diffusion,convection,pressure,capillarity,electroosmosis and electromigration.(2)The mechanism of chloridediffusionprocess has been analyzed and the advantages and disadvantages of the traditional chloride diffusion model based on Fick's second lawhave been discussed.The importance of chloride binding to establishthe modified chloride diffusion modelhas been expounded.(3)The relationship between chloride concentration and free chloride concentration has been fitted by linear and non-linearisotherms based on the experimental data.The fitting degree of linear and non-linear isotherms and the influence on the apparent diffusion coefficient of chloride has been studied.(4)The traditional Fick's model and the chloride diffusion process by considering three kinds of non-linear isothermhave been modeled and analyzed.Thefactorsandlawsofhow non-linear isotherm influenceschloride diffusion processhave been studied.Finally the applicability and feasibility of the three kinds of non-linear isothermhave been discussed by comparing the simulation values with the testresults.(5)The chloride apparent diffusion coefficients at different times have beencalculated by extracting the concentration values at each time.Then the influence of different non-linear isotherms on the chloride transport process has been further studied by analyzing therelationship between the apparent diffusion coefficient and time.(6)The reliability-based method has beenstudied to predict the durability life of reinforced concrete structures.According to the failure criterion of concrete durability,the failure probability of the structure has been calculated based on Monte Carlo methodby using MATLAB software.Then the frequency distribution of the failure time has been analyzed and the effects of different structural parameters on the failure probability and durability life of concrete have been compared.In this paper,the research results of chloride binding capacity and numerical analysis can be used as a basis forthe modificationofchloride transport model in marine environments,and the reliability-based method for predicting the durability life of concrete structures can also provide a basis for a more reasonable durability life prediction of concrete structures,which can provide some referencesfor further similar research.