Modelling the effect of corrosion on bond in reinforced concrete

Corrosion of reinforcement leads to a volume increase; thus, splitting stresses are induced in the concrete. Thereby, the bond mechanism between the reinforcement and the concrete is influenced. In order to model the splitting stresses of the corrosion, the mechanical behaviour of the corrosion products must be known. Analyses of corrosion cracking tests led to the assumption that the corrosion products behave like a granular material: i.e. their stiffness increases with the stress level. This mechanical behaviour, and the volume of the rust relative to the uncorroded steel, were given as input for a corrosion layer. This layer was used, together with a model developed earlier for the bond mechanism, in finite element analyses of corrosion cracking tests and pull-out tests with corroded reinforcement. Reasonably good agreement between test results and analyses was obtained. The results show that this method of modelling can predict the decrease of bond when splitting of the concrete occurs, due to the combined action of corrosion and the bond mechanism.