Noori Dolooee, Golshid2025-10-012025-10-012025-10-01http://hdl.handle.net/10393/50892https://doi.org/10.20381/ruor-31423Corrosion of embedded reinforcement remains one of the most critical deterioration mechanisms compromising the longevity and serviceability of reinforced concrete (RC) structures. The Damage Rating Index (DRI), a microscopic technique that has been employed for assessing concrete damage induced by internal swelling reactions, has not yet been applied to the assessment of reinforcement corrosion-induced damage. This study investigates the applicability and sensitivity of the DRI protocol in evaluating corrosion-induced cracking in the RC. A series of cylindrical RC specimens with two water-to-cement ratios (0.4 and 0.54) and a range of concrete cover-to-rebar diameter ratios were subjected to accelerated corrosion to achieve a target reinforcing steel mass loss of 5% embedded. Microscopic examination and DRI quantification were conducted on polished sections of concrete, focusing on two key deterioration features: cracks in the cement paste (CCP) and cracks with reaction products in the cement paste (CCP-RP). The findings demonstrate that the DRI effectively captures variations in damage pattern and severity as a function of mixture design and cover depth. An extended DRI approach, incorporating normalized crack densities and area-based analyses, further substantiated the sensitivity of the method. A corrosion damage classification model was proposed, integrating DRI counts, normalized crack areas, and visual observations to define five progressive levels of deterioration. The results establish the DRI as a viable diagnostic tool for quantifying microstructural damage due to reinforcement corrosion, marking the first demonstration of its application beyond internal swelling reactions and underscoring its potential as a broader framework for structural durability assessment.enDamage Rating Index (DRI)corrosion-induced crackingreinforced concretecement paste crackingdurability assessmentThesis