Understanding the mechanical behaviour of natural soils as mixed with cement for stabilization is crucial for civil engineering developments. The response of cement-soil admixtures when subjected to cyclic loads is a largely unexplored topic, despite the importance of understanding fatigue in these ubiquitous construction materials. We present cyclic loading experiments on Portland cement mixed with fragmented shale fragments using triaxial testing, monitored with synchrotron-based μCT. Through digital volume correlation (DVC), the temporal evolution of the displacement, volumetric, and von Mises equivalent strain fields were obtained. We observed in detail the fatigue damage evolution during cyclic loading and found that following high-strain deformation of the much softer shale fragments, the ultimate failure of the samples occurred in the adjacent cement matrix. The failure mechanism under periodic stress and its relevance for accelerated laboratory testing of slow degradation long-term processes are of key importance to technical infrastructure, including subsea CO2 storage.

中文翻译：

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原位同步加速器微计算机断层扫描监测的循环三轴载荷下水泥和页岩外加剂的机械响应


了解天然土壤与水泥混合以稳定土壤的机械性能对于土木工程开发至关重要。水泥-土壤外加剂在承受循环载荷时的响应在很大程度上是一个未被探索的话题，尽管了解这些无处不在的建筑材料中的疲劳很重要。我们提出了使用三轴测试对混合了碎裂页岩碎片的波特兰水泥进行循环加载实验，并使用基于同步加速器的 μCT 进行监测。通过数字体积相关 （DVC），获得了位移、体积和 von Mises 等效应变场的时间演变。我们详细观察了循环加载过程中的疲劳损伤演变，发现在较软的页岩碎片发生高应变变形后，样品的最终破坏发生在相邻的水泥基质中。周期性应力下的失效机制及其与缓慢降解长期过程的加速实验室测试的相关性，对于技术基础设施（包括海底 CO2 封存）至关重要。