A Micro-mechanics Based Corrosion Model for Predicting the Service Life of Reinforced Concrete Structures

In reinforced concrete structures, the steel rebars embedded in concrete are protected from corrosion by passive film on the steel surface due to high alkalinity. Corrosion is initiated by the ingress on chloride ions which leads to the break down of passive film formed on the steel surface. Onc corrosion has initiated accumulation of corrosion products occurs on the steel surface. Since these products occupy a volume several times larger than that of the original steel, the result is thus an increase of the internal tensile stresses leading to cracking and spalling of cover concrete, which no only reduces the durability performance but also affect the structural properties of reinforced concrete(RC) structures. In this paper, a service life prediction of RC structures is carried out by usin a micro-mechanics based corrosion model. The corrosion model consists of a chloride penetration model to evaluate the initiation of corrosion and an electric corrosion cell model and an oxygen diffusion model to evaluate the rate and the accumulated amounts of corrosion products. Then, a corrosion cracking model is combined with the above models to evaluate the critical amount of corrosion product required for initiation cracking in cover concrete. By implementing the models into a finite element analysis program, a time and space dependent corrosion analysis and a service life prediction of RC structures due to chloride attack are simulated and the results of the analysis are compared with test the results. The effect of crack width the corrosion and the service life of the RC structures are analyzed and discussed.