Abstract：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.
