Guan Zhongzheng, Zhang Haochang, Gao Yan, Song Pengfei, Li Yong, Wu Lipeng, Wang Yichao
Key Laboratory of Roads and Railway Engineering Safety Control, Ministry of Education, Shijiazhuang Tiedao University, Shijiazhuang 050013, China.
Materials (Basel). 2023 Sep 12;16(18):6167. doi: 10.3390/ma16186167.
External sulfate attack is an important factor causing a decrease in the mechanical properties of cement-based materials. In this paper, a computational prediction model of elastic modulus, considering the characteristics of sulfate corrosion from outside to inside and the influence of the interface transition zone (ITZ), was established to predict the elastic modulus of mortar under the external sulfate attack. Firstly, the backscattered electron (BSE) images of mortar and the algorithm of image threshold segmenting were used to determine a reasonable thickness of corroded ITZ. Secondly, the nanoindentation test was adopted to acquire the microscopic elastic parameters of phases (sand, cement, and ITZ) in corroded mortar. Moreover, the mortar mix proportion and Lu and Torquato's model were adopted to calculate the volume fractions of phases. Finally, a computational prediction model of elastic modulus of mortar under sulfate attack was proposed with homogenization methods. The results indicate that the thickness of corroded ITZ is 20 mm, and the error values of elastic modulus between the theoretical prediction results and the experimental results are within 8%, indicating that the macroscopic elastic modulus of corroded mortar can be precisely predicted by the computational prediction model of elastic modulus.
外部硫酸盐侵蚀是导致水泥基材料力学性能下降的一个重要因素。本文建立了一个考虑从外到内硫酸盐侵蚀特性及界面过渡区（ITZ）影响的弹性模量计算预测模型，用于预测外部硫酸盐侵蚀作用下砂浆的弹性模量。首先，利用砂浆的背散射电子（BSE）图像和图像阈值分割算法确定腐蚀ITZ的合理厚度。其次，采用纳米压痕试验获取腐蚀砂浆中各相（砂、水泥和ITZ）的微观弹性参数。此外，采用砂浆配合比以及Lu和Torquato模型计算各相的体积分数。最后，利用均匀化方法提出了硫酸盐侵蚀作用下砂浆弹性模量的计算预测模型。结果表明，腐蚀ITZ的厚度为20mm，理论预测结果与试验结果的弹性模量误差值在8%以内，表明该弹性模量计算预测模型能够精确预测腐蚀砂浆的宏观弹性模量。
