MODELS FOR CHLORIDE INGRESS INTO CONCRETE - FROM COLLEPARDI TO TODAY
The first model to predict chloride ingress into concrete was presented byCollepardi in 1970,in Italian! That model was used for some 20 years for design of concretestructures before it was realized that the main parameter,the apparent chloride diffusioncoefficient,is not a material property! Since then the Collepardi model has been significantlyimproved and developed into more or less sophisticated probabilistic models. Today we havenumerous models for predicting chloride ingress but all of them have serious limitations thatrestrict the present use for long term predictions.The paper describes the history of developingchloride ingress models. An overview is given of the fundamental differences betweenvarious models,from those based on Ficks 2nd law and constant or time-dependent diffusioncoefficients and surface chloride contents to those based on chloride transport equations withor without a multi-species approach. The three main limitations are shown to be the lack ofunderstanding the time-dependency of the apparent chloride diffusion coefficients,and thelack of good long-term data,the chloride content increase with time close to the exposedsurface and the difficulties in quantifying the boundary conditions for sophisticated ingressmodels.
chloride ingress models flux interaction binding
Lars-Olof Nilsson
Laboratory of Building Materials,Lund University,Sweden
国际会议
The International Conference on Durability of Concrete Structures(2008年混凝土结构耐久性国际学术会议)
杭州
英文
36-42
2008-11-01（万方平台首次上网日期，不代表论文的发表时间）