Numerical Simulation And Analysis Of Chloride Diffusion In Concrete

Reinforced concrete structure is one of the most common main structures in modern civil engineering.Its lacking of durability makes the engineering safety issues become increasingly prominent in the marine environment.The length of service of reinforced concrete structure in the marine environment mainly focuses on the induction period.This stage has the longest time and the most influence factors.To extend the service period of the reinforced concrete structure from the viewpoint of durability,extending time and controlling the influence factors in the induction period are the most effective and practical ways.The length of service of ocean engineering is quite long and its environment is difficult to carry out in the laboratory.Hence,applying numerical simulation method,Fick’s second law and index partial differential equations to establish mathematical model,this paper use COMSOL finite element analysis software to simulate the chloride diffusion law of two typical cross-section in reinforced concrete structure.The key factors of this paper,which influence the length of the induction period,are water-cement ratio,protective layer thickness and bar diameter.The research result shows that chloride diffusion law in concrete are similar under circular and rectangular cross-section and the effect of the bar diameter on induction period is negligible.Under a certain protective layer thickness,the lower water-cement ratio,the slower diffusion of chloride in concrete and the longer the induction period.Reducing the water-cement ratio appropriately can extend the induction period in concrete.Under a certain water-cement ratio,the thicker the protective layer thickness,the longer the induction period.Taking the economics of the project into account,protective layer thickness in the 60~80 mm is more appropriate in splash zones.Concerning chloride diffusion coefficient,which plays a decisive role on steel corrosion,this paper choose PDE coefficient type partial differential equations module to establish two-dimensional finite element model.For the severe corrosion of offshore structures in splash zones,this model established in the splash zones has some significance for the actual.