A novel, combined experimental-modelling approach is presented for the estimation of the corrosion depth, load bearing capacity and lifetime of unreinforced concrete sewer pipes exposed to prolonged biogenic sulphide corrosion. The biogenic sulphide corrosion process is mimicked through two types of representative chemical experiments, namely: (i) experiments performed under pH conditions, where dry-cast concrete cube samples are exposed to monthly refreshed sulphuric acid solutions with initial pH values of 3, 2 and 1 for a period of 12 months, and (ii) experiments carried out under pH conditions, in which dry-cast concrete disk samples are subjected to sulphuric acid solutions with almost constant pH values of 2, 1 and 0.5 for a period of two months. By applying X-ray diffraction, optical microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy analyses, insight into the micro-scale morphology and elemental composition of the corrosion profile is obtained. In addition, the corrosion front and depth characteristics are measured by conducting phenolphthalein tests and analyses of surface colour and texture of macro-scale samples. From the experimental results, the time course of the corrosion depth is calibrated with a model for sulphate attack under a constant pH level. The model formulation is combined with detailed finite element method results from the literature to predict the long-term load bearing capacity of a concrete sewer pipe. The model is subsequently generalised for sulphate corrosion under a varying pH level. When combined with the installation of pH measuring devices on the inside of sewer pipes, the current engineering model may serve as an excellent practical tool for continuously monitoring the structural health and predicting the lifetime of in-situ sewer systems subject to sulphate attack under random acidity fluctuations.

中文翻译：

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一种对暴露于生物硫化物腐蚀的混凝土下水道系统进行寿命预测和结构健康监测的新方法

提出了一种新颖的组合实验建模方法，用于估计暴露于长期生物硫化物腐蚀的无筋混凝土污水管道的腐蚀深度、承载能力和寿命。通过两种典型的化学实验来模拟生物硫化物腐蚀过程，即：（i）在 pH 条件下进行的实验，其中干铸混凝土立方体样品暴露于每月更新的初始 pH 值为 3、2 和 2 的硫酸溶液中。 1 为期 12 个月，以及 (ii) 在 pH 条件下进行的实验，其中干铸混凝土圆盘样品在 pH 值几乎恒定为 2、1 和 0.5 的硫酸溶液中浸泡两个月。通过应用 X 射线衍射、光学显微镜、扫描电子显微镜和能量色散 X 射线光谱分析，可以深入了解腐蚀轮廓的微观形貌和元素组成。此外，通过酚酞测试和宏观样品的表面颜色和纹理分析来测量腐蚀前沿和深度特征。根据实验结果，腐蚀深度的时间进程是用恒定 pH 水平下的硫酸盐侵蚀模型进行校准的。该模型公式与文献中详细的有限元方法结果相结合，可以预测混凝土污水管道的长期承载能力。该模型随后被推广到不同 pH 水平下的硫酸盐腐蚀。当与在下水道管道内部安装 pH 测量装置相结合时，当前的工程模型可以作为一个优秀的实用工具，用于连续监测结构健康并预测在随机酸度下遭受硫酸盐侵蚀的原位下水道系统的寿命波动。