Yao Jinwei, Chen Jiankang, Lu Chunsheng
Key Laboratory of Impact and Safety Engineering, School of Mechanical Engineering and Mechanics, Ningbo University, Ningbo 315211, China.
Zhejiang Business Technology Institute, Ningbo 315012, China.
Materials (Basel). 2019 Jul 23;12(14):2338. doi: 10.3390/ma12142338.
Sulfate attack tests were performed on concrete samples with three water-to-cement ratios, and micro-crack growth patterns on concrete surfaces were recorded. The expansive stress and crack nucleation caused by delayed ettringite formation (DEF) were studied using X-ray diffraction and scanning electron microscopy. By means of a digital image processing technology, fractal dimensions of surface cracking patterns were determined, which monotonously increase during corrosion. Moreover, it is shown that the change of fractal dimensions is directly proportional to accumulation of DEF, and therefore, a simple theoretical model could be proposed to describe the micro-crack evolution in concretes under sulfate attack.
对三种水灰比的混凝土样品进行了硫酸盐侵蚀试验，并记录了混凝土表面的微裂纹扩展模式。使用X射线衍射和扫描电子显微镜研究了延迟钙矾石形成（DEF）引起的膨胀应力和裂纹形核。借助数字图像处理技术，确定了表面裂纹模式的分形维数，其在腐蚀过程中单调增加。此外，结果表明分形维数的变化与DEF的积累成正比，因此，可以提出一个简单的理论模型来描述硫酸盐侵蚀下混凝土中的微裂纹演变。
