Accelerated impressed current testing is the most common experimental method for assessing the susceptibility to corrosion-induced cracking, the most prominent challenge to the durability of reinforced concrete structures. Although it is well known that accelerated impressed current tests lead to slower propagation of cracks (with respect to corrosion penetration) than in natural conditions, which results in overestimations of the delamination/spalling time, the origins of this phenomenon have puzzled researchers for more than a quarter of a century. In view of recent experimental findings, it is postulated that the phenomenon can be attributed to the variability of rust composition and density, specifically to the variable ratio of the mass fractions of iron oxide and iron hydroxide-oxide, which is affected by the magnitude of the applied corrosion current density. Based on this hypothesis, a corrosion-induced cracking model for virtual impressed-current testing is presented. The simulation results obtained with the proposed model are validated against experimental data, showing good agreement. Importantly, the model can predict corrosion-induced cracking under natural conditions and thus allows for the calculation of a newly proposed crack width slope correction factor, which extrapolates the surface crack width measured during accelerated impressed current tests to corrosion in natural conditions.

中文翻译：

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揭示钢筋腐蚀速率与钢筋混凝土腐蚀引起的开裂之间的相互作用


加速外加电流测试是评估对腐蚀引起的开裂敏感性的最常用实验方法，这是对钢筋混凝土结构耐久性最突出的挑战。尽管众所周知，加速外加电流测试会导致裂纹的扩展速度（相对于腐蚀渗透）比自然条件慢，从而导致对分层/剥落时间的高估，但这种现象的起源一直困扰着研究人员超过四分之一个世纪。鉴于最近的实验结果，可以假设这种现象可以归因于铁锈成分和密度的变化，特别是氧化铁和氢氧化铁-氧化物的质量分数的可变比率，它受施加腐蚀电流密度的大小的影响。基于这一假设，提出了一种用于虚拟外加电流测试的腐蚀诱发开裂模型。使用所提出的模型获得的仿真结果与实验数据进行了验证，显示出良好的一致性。重要的是，该模型可以预测自然条件下腐蚀引起的开裂，从而可以计算新提出的裂纹宽度斜率修正因子，该系数将在加速外加电流测试期间测量的表面裂纹宽度外推到自然条件下的腐蚀。