This paper presents results on corrosion characteristics of 66 rebars extracted from un- and pre-cracked plain concrete and fibre-reinforced concrete (FRC) beams suffering from corrosion for more than 3 years. The influences of fibre reinforcement, flexural cracks, corrosion-induced cracks and loading condition on the maximum local corrosion level (defined as the maximum cross-sectional area loss percentage) and pit morphology were examined. With 3D-scanning, the corrosion characteristics were analysed, and pit types were classified based on the maximum local corrosion level and geometric parameters of pits. Corrosion pits were observed near some flexural cracks, while the bars at other cracks were free from corrosion. Most rebars in FRC had less maximum local corrosion level than those in plain concrete under the same loading condition and maximum flexural crack width. However, the maximum local corrosion level was not dependent on the maximum flexural crack width (0.1 and 0.4 mm). Longitudinal cracks (corrosion-induced cracks) aggravated the total steel loss and changed the pit morphology by promoting the pit length development. However, longitudinal cracks did not always form, even with severe pitting corrosion. A hypothesis about the time-dependent interplay between transverse and longitudinal cracks and corrosion development was proposed. Further studies on predicting the pitting corrosion evolution and experimental work on specimens exposed for longer periods are needed to understand and quantify the long-term durability of concrete structures reinforced with both conventional reinforcing bars and fibres.

中文翻译：

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预开裂素混凝土梁和纤维钢筋混凝土梁混凝土裂缝与钢筋锈蚀特性的相关性

本文介绍了从腐蚀超过 3 年的未开裂和预开裂素混凝土和纤维增强混凝土 (FRC) 梁中提取的 66 根钢筋的腐蚀特性结果。研究了纤维增强、弯曲裂纹、腐蚀诱导裂纹和加载条件对最大局部腐蚀水平（定义为最大横截面积损失百分比）和凹坑形态的影响。通过3D扫描，分析腐蚀特征，并根据最大局部腐蚀水平和坑的几何参数对坑类型进行分类。在一些弯曲裂纹附近观察到腐蚀坑，而其他裂纹处的钢筋没有腐蚀。在相同的荷载条件和最大弯曲裂缝宽度下，大多数 FRC 中的钢筋的最大局部腐蚀水平低于素混凝土中的钢筋。然而，最大局部腐蚀水平不依赖于最大弯曲裂纹宽度（0.1 和 0.4 毫米）。纵向裂纹（腐蚀引起的裂纹）加剧了钢的总损失并通过促进坑长度的发展改变了坑的形态。然而，纵向裂纹并不总是形成，即使是严重的点蚀。提出了关于横向和纵向裂纹与腐蚀发展之间随时间变化的相互作用的假设。