Corrosion Pattern and Mechanical Behaviour of Corroded Rebars in Cracked Plain and Fibre Reinforced Concrete

Abstract

This paper presents experimental results of corrosion pattern and tensile behaviour of corroded rebars extracted from 4 uncracked and 18 pre-cracked plain concrete and fibre reinforced concrete (FRC) beams. The beams were pre-cracked through three-point bending to a target maximum crack width of 0.1 and 0.4 mm, and then subjected to natural corrosion through cyclic exposure to a 16.5% NaCl solution for more than three years. 3D-scanning was used to characterise the pit morphology and evaluate the maximum local corrosion level of extracted rebars. Under the same loading condition and crack width, most rebars in FRC had smaller maximum local corrosion level than those in plain concrete. Subsequently, tensile tests were carried out on the extracted rebars, with Digital Image Correlation (DIC) technique adopted to investigate the influence of pit morphology on the local strain development. Finally, the time-dependent influence of transverse and longitudinal cracks on the pit morphology which governs the ultimate strain of corroded rebars was discussed. The time-varying nature of corrosion morphology should be considered when predicting the durability and long-term safety of conventional reinforced concrete and FRC structures with reinforcing bars under chloride environments.