Effect of water-cement ratio and current density on accelerated corrosion-induced cracking

It is not fully understood how corrosion-induced cracking in reinforced concrete is affected by corrosion rate.Improved understanding of this effect is important because it assists with predicting the state of structures which suffer from corrosion-induced cracking based on results of accelerated laboratory tests with confidence.Possible reasons for the effect of corrosion rate on corrosion-induced cracking are creep of concrete, migration of corrosion products into pores and cracks, and composition of corrosion products.Here, we test the effect of creep.We carry out corrosion experiments on specimens consisting of a single reinforcement bar embedded in a concrete cylinder.We vary corrosion rates and water-cement ratios of concrete.The modelling of corrosion-induced cracking is carried out with a lattice approach based on a visco-elastic damage-plasticity constitutive model which predicts the effects of linear creep, but not the migration of corrosion products nor the effect of corrosion rate on corrosion products.With this choice of model, we test if creep together with fracture can reproduce the effects of water-cement ratio and corrosion rates.Based on our experimental results, corrosion penetration at a fixed surface crack width increases with decreasing corrosion rate and increases with increasing water-cement ratio.The lattice approach with fracture and creep but without corrosion product migration is not able to reproduce the dependencies of rate and water-cement ratio on critical corrosion penetration satisfactorily.