Influence of pre-existing cracks and concrete cover on service life of reinforced concrete and mechanical behaviour of corroded rebars

PurposeIncorporating pre-existing crack in service life prediction of reinforced concrete structures subjected to corrosion is crucial for accurate assessment, realistic modelling and effective decision-making in terms of maintenance and repair strategies.Design/methodology/approachAn accelerated corrosion test was conducted by using impressed current method on cylindrical specimens with varying cover thickness and crack width. Mechanical properties of the specimens were evaluated by tensile tests.FindingsThe results show that, the pre-cracked samples exhibited shorter concrete cover cracking times, particularly with wider cracks when compared to the uncracked samples. Moreover, the load-bearing capacity of the reinforcement bars decreased owing to the pre-cracks, causing structural deflection and a shortened yield plateau. However, the ductility index remained consistent across all sample types, implying that the concrete had good overall ductility. Comparing the results of the non-corroded rebar and corroded rebar samples, the maximum reduction in the yield load was 25.22%, whereas the maximum reduction in the ultimate load was 26.23%. The simple mathematical model proposed in this study provides a reliable method for predicting the chloride ion diffusion coefficient in cracked concrete of existing reinforced concrete structures.Originality/valueA simple mathematical model was proposed for evaluation of the equivalent chloride ion diffusion coefficient considering crack width, average crack spacing and crack extending lengths for cracked reinforced concrete structures, which is used to incorporate existing crack in service life prediction models.