基于可视化分析的玄武岩纤维#br# 喷射混凝土微观结构研究

玄武岩纤维(BF)掺入引起的孔隙结构变化是影响玄武岩纤维喷射混凝土(BF/SC)力学性能提高的关键因素。纤维与基体密度相近,CT扫描图像区分度较小,传统方法无法直接识别纤维原位分布。可采用分水岭算法和骨架提取算法相结合突破这一瓶颈。文章采用喷射混凝土制作方式，研究了不同BF掺量对BF/SC力学性能的影响；借助CT扫描技术对 BF/SC 微观结构进行可视化分析，测定了BF不同掺量下的孔隙大小组分结构、纤维分布；分析纤维掺量与孔隙结构的响应关系,揭示纤维增强微细观机理。结果表明：玄武岩掺量比为3kg/m3时，喷射混凝土的抗压和抗折性能最好；此时孔隙率为4.36%，大孔隙占比最少；内部结构的纤维分散的比较均匀，且纤维分布方向有利于控制裂缝的产生。当BF掺量大于该值时，其抗压和抗折性能大大降低，引起了总孔隙率提高,出现纤维严重结团现象，导致BF/SC内部大孔隙的增加，这是导致混凝土力学性能恶化的主要原因。

Microstructure of basalt fiber shotcrete based on visual analysis

The change of pore structure caused by the incorporation of basalt fiber (BF) is the key factor to improve the mechanical properties of basalt fiber shotcrete (BF/SC). The density of fiber is similar to that of matrix, and the differentiation of CT image is small, so the traditional method can not directly identify the in-situ distribution of fiber. Watershed algorithm and skeleton extraction algorithm are combined to break through this bottleneck. In this experiment, shotcrete was used to study the effect of different BF content on the mechanical properties of BF / SC; the microstructure of BF / SC was visualized by CT scanning technology, and the pore size component structure and fiber distribution were measured under different BF content ratio; the response relationship between fiber content and pore structure was analyzed to reveal the micro mechanism of fiber reinforcement. The results show that when the content ratio of basalt is 3kg / m3, the compressive and flexural properties of shotcrete are the best; at this time, the porosity is 4.36%, and the proportion of macropores is the least; the fiber of internal structure is more evenly distributed, and the fiber distribution direction is conducive to control the generation of cracks. When the content ratio of BF is greater than this value, the compressive and flexural properties of the concrete are greatly reduced, resulting in the increase of the total porosity, serious fiber agglomeration and the increase of the internal macropores of BF / SC, which is the main reason for the deterioration of the mechanical properties of the concrete.