The effect of corrosion rate on corrosion-induced cracking in reinforced concrete

Corrosion of steel in concrete is responsible for 70-90% of the premature deterioration of reinforced concrete structures and can even cause structural failure, as infamously documented by the recent collapse of aerated concrete panels in the UK.Under field conditions, corrosion of reinforced concrete is a slow process that takes years or decades.Therefore, high corrosion rates are artificially applied in laboratory conditions to shorten the duration of experiments.It has been known for decades that this underestimates the damage caused by corrosion under natural conditions, but the reasons for this have been unclear.Based on recent experimental results, we propose a hypothesis that explains this phenomenon by the variability of the chemical composition of rust, in particular the variable ratio of iron oxides and iron hydroxy-oxides, with the applied corrosion rate.The simulation results obtained were found to be able to reproduce the hitherto puzzling trends in the experimental data for different corrosion rates.The proposed model can be used to estimate the error caused by the acceleration of corrosion tests and to extrapolate the results to the natural corrosion regime.