Research On Permeability Of Road Concrete By Diffusion Coefficient Of Chloride Ion

Because of strong bearing capacity and wide source of cement,the cement concrete pavement has been widely used.However,by the current action of natural environmental factors and heavy-load traffic, diseases of cement concrete pavement is increasingly serious, some damages and pollutions such as freezing, dissolution, automobile exhaust carbonization and outside corrosion are all caused by those mediums of water and infiltration. If the outside invasions such as water, gas and corrosive ions can be effectively prevented into the material, the service life of cement concrete pavement can be prolonged.So the key measure to improve the performance of road concrete and to prevent these diseases is to solve the problem of permeability of road concrete,and chloride ion diffusion coefficient is the most classic indicators to evaluate permeability. Therefore, considerate about economy and practicality, this paper choose chloride ion diffusion coefficient as the evaluation index of anti-permeability of road concrete to research the anti-permeability of road concrete.Based on the relevant knowledges of concrete materials science and statistics, this paper establishes the random aggregate distribution model of concrete by numerical simulation to calculate chloride ion diffusion coefficient, models in relationship of ion permeability of concrete and pore structure by the theory of micro pore, and systematically analyzes the evaluation methods of anti-permeability of road concrete.This paper mainly includes these following aspects:(1) According to the relationship between the cumulative distribution function and aggregate size, this paper establishes a random aggregate numerical model of concrete by Matlab language and calculates chloride ion diffusion coefficient of concrete by the random aggregate model and discusses the influence of chloride ion permeability of concrete by the aggregate and interface.(2) Based on statistics theory, this paper analyzes the relationship between the pore structure,the parameters of pore volume and chloride ion diffusion coefficient of road concrete by fractal theory, also models the chloride ion anti-permeability of road concrete with pore structure by multiple regression analysis of the pore parameters and chloride ion diffusion coefficient.(3) This paper studies the chloride ion diffusion coefficient under axial compressive loads and bending loads, and compares the changes of chloride ion diffusion coefficient in the different actions of loads and unloading to reflect the situation of chloride ion permeability in road concrete more realistically.(4) This paper establishes stranded water diffusion model in rainy region to reflect the permeability of water in the road concrete more accurately, and compares the relationship between water diffusion coefficient and chloride ion diffusion coefficient, also put forward some measures to improve the performance of permeability of cement concrete pavement.This paper analyzes systematically the performance of permeability of road concrete by multiple aspects, because of the clear theory,.complete system,and good practicality, this paper has the value of reference to the study about performance of anti-permeability of cement concrete pavement.