Influence of Crack Width on Long Term Degradation of Concrete Structures

The study of the influence of concrete crack width on corrosion of steel reinforcement due to exposure to aggressive environments is very important for durability design. Premature failure of structures may eventually occur during their service life. Since cracks in the concrete cover are inevitable due to the stress structures are subjected to, penetration of aggressive substances will occur more rapidly in cracked areas than in areas without cracking. This study addresses the corrosion effects on the reinforcement in cracked areas. Reinforced beams 2 m long and cracked at half-length with widths up to 1 mm were prepared 20 years ago, exposed to carbonation and chlorides and kept outdoors sheltered from rain until present. After 20 years, the carbonation depth in the faces of the cracks, and the reinforcement at the crack region have been examined. The results indicated that flexural cracks in high quality carbonated concrete present only a small additional risk of corrosion which, however, is significant in the presence of chlorides.