Mechanical properties of corroded steel bars in pre-cracked concrete suffering from chloride attack

• A 4-year chloride-induced corrosion of steel bar in cracked concrete is achieved.
• Obvious pitting corrosion occurs on embedded bars due to the transverse crack.
• Both nominal strengths and ductility decrease with increasing the corrosion degree.
• The non-uniform coefficient can effectively assess the mechanical properties.

A 4-year natural corrosion experiment coupled with a cyclic wetting-drying process with 5% NaCl solution and an indoor natural corrosion process was carried out for pre-cracked reinforced concrete elements in this study. The diameter loss along the bar length which was greatly influenced by crack effect was measured, and the degree of corrosion evaluated by average mass loss was calculated for all cleaned bar specimens. The tensile test results showed that both the nominal yield and ultimate strengths and the percentage elongation decreased with the increase of mass loss, and that the effect of corrosion on degradation of ductility was much greater than that of tensile strengths. Taking the impact of pitting corrosion into account, a non-uniform coefficient, S, directly related to pit depths of corroded bars was proposed and the degradation models of yield strength, ultimate strength and percentage elongation were derived based on S. It seems that this method might be a more effective way to assess the mechanical properties of corroded bars with obvious pits. Finally, the reduced area at necking and fracture surface morphology were compared between sound and corroded bars.