Markert Martin, Katzmann Josef, Birtel Veit, Garrecht Harald, Steeb Holger
Materials Testing Institute, University of Stuttgart, Pfaffenwaldring 4d, 70569 Stuttgart, Germany.
Institute of Applied Mechanics (CE), University of Stuttgart, Pfaffenwaldring 7, 70569 Stuttgart, Germany.
Materials (Basel). 2021 Dec 23;15(1):91. doi: 10.3390/ma15010091.
High-performance concrete (HPC) is a topic of current research and construction projects, due to its outstanding compressive strength and durability. In particular, its behaviour under high-cycle fatigue loading is the focus of current investigations, to further pave the way to highly challenging long-lasting constructions; e.g., bridges or offshore buildings. In order to investigate the behaviour of HPC with different moisture contents in more detail, a mixture of silica sand and basalt aggregate with a maximum grain size of 8 mm was investigated with three different moisture contents. For this purpose, cyclic compressive fatigue tests at a loading frequency of 10 Hz and different maximum stress levels were performed. The main focus was the moisture influence on the number of cycles to failure and the development of concrete temperature and strain. In a further step, only the mortar matrix was investigated. For this purpose, the mixture was produced without basalt, and the moisture influence was investigated on smaller-sized test specimens using dynamic mechanical analysis (DMA) and X-ray computed tomography (XRCT). It was shown that the moisture content of HPC had a significant influence on the fatigue damage behaviour due to the number of cycles to failure decreasing significantly with increased moisture. In addition, there was also an influence on the temperature development, as well as on the strain development. It was shown that increasing moisture content was associated with an increase in strain development. XRCT scans, in the course of the damage phases, showed an increase in internal cracks, and made their size visible. With the help of DMA as a new research method in the field of concrete research, we were also able to measure damage development related to a decrease in sample stiffness. Both methods, XRCT and DMA, can be listed as nondestructive methods, and thus can complement the known destructive test methods, such as light microscopy.
高性能混凝土（HPC）因其出色的抗压强度和耐久性，成为当前研究和建设项目的一个课题。特别是，其在高周疲劳荷载作用下的性能是当前研究的重点，以便为极具挑战性的持久建筑（如桥梁或海上建筑）进一步铺平道路。为了更详细地研究不同含水量的高性能混凝土的性能，对最大粒径为8毫米的硅砂和玄武岩骨料混合物进行了三种不同含水量的研究。为此，在10赫兹的加载频率和不同的最大应力水平下进行了循环压缩疲劳试验。主要重点是水分对破坏循环次数、混凝土温度和应变发展的影响。在进一步的步骤中，仅对砂浆基体进行了研究。为此，制作混合物时不使用玄武岩，并使用动态力学分析（DMA）和X射线计算机断层扫描（XRCT）对较小尺寸的试件研究水分影响。结果表明，高性能混凝土的含水量对疲劳损伤行为有显著影响，因为破坏循环次数随含水量增加而显著减少。此外，对温度发展以及应变发展也有影响。结果表明，含水量增加与应变发展增加有关。在损伤阶段的X射线计算机断层扫描显示内部裂缝增加，并使其尺寸可见。借助动态力学分析这一混凝土研究领域的新研究方法，我们还能够测量与样品刚度降低相关的损伤发展。X射线计算机断层扫描和动态力学分析这两种方法都可列为无损检测方法，因此可以补充已知的破坏性检测方法，如光学显微镜。
