This paper presents results of a concrete bridge investigation on R-445 regional road, Ilijaš municipality, Bosnia and Herzegovina. The investigation is performed by visual inspection and testing, as an operation required for repair works, following European legislation related to the assessment of existing structures. European standards were applied for the process of structural investigation and collecting data necessary for eventual repair, as well as for the evaluation of built-in materials by testing. The scope and procedure for the investigation are briefly described, including visual inspection and experimental testing. Description of used destructive and non-destructive test methods for determining the structural characteristics and condition of built-in materials are given, regarding in-situ compressive strength, hardness, content of chlorides in hardened concrete, depth of carbonation, thickness of the protective layer of concrete, diameters and arrangement of reinforcement. Obtained results and conclusions are presented and analyzed regarding further possible repair. Since there were no data on built-in materials properties, in-situ concrete compressive strength determination process was performed, following instructions defined by the standard for assessment of an in-situ compressive strength. Different options are considered for strength determination, regarding the use of only core testing data or combination of core testing and rebound hammer method, with established correlation between the core compressive strength and the rebound number for the tested type of concrete. Structure weaknesses caused by the lack of maintenance, insufficient care in the separation of the river aggregate used in concrete mixture and inadequate compaction of concrete, are pointed out. Considering noted aggressiveness of built-in concrete towards reinforcement, carbonization depth and chloride ions content results were discussed. Based on experimental results and visual inspection, recommendations are given for further defining more stringent conditions for the content of chlorine ions in concrete containing steel reinforcement or being a part of composite structure, compared to those defined by the regulations.
