Crack Behavior near Reinforcing Bars in Concrete Structures

Currently used design methods predict that the crack widths at the concrete surface will increase significantly with concrete cover Requirements concerning limitation of crack widths therefore make it difficult to use large concrete covers, which are otherwise desirable to reduce the reinforcement corrosion. For this reason, it would be more relevant to use the crack width in the vicinity of the reinforcing bars as an indicator. In this paper an experimental study to investigate how different parameters affect the crack width at the reinforcement level is presented. Axially loaded concrete prisms with central reinforcing bars were tested with a method that makes it possible to indirectly investigate crack widths near the reinforcement. Concrete cover bar diameter and concrete quality were varied. The test results show that the crack width close to the bar is affected only to a limited extent by concrete cover, bar diameter and concrete quality, as well as by the fact that steel stress is the dominating parameter.