Microstructural characterization of fiber-matrix interface for fiber-reinforced cementitious composites and their mechanical properties

The complicated microstructure of fiber-reinforced cementitious composites, which includes the fiber-matrix interface, results in complex mechanical behavior. To study the effects of the microstructure, micro-computed tomography (micro-CT) image analysis was performed in this study. A newly developed fiber segmentation approach, which allows for more objective fiber segmentation, was used to generate virtual samples. These samples consist of five distinct phases: pores, fibers, outer product, inner product, and unhydrated phases derived from reconstructed images. The fiber-matrix interface was identified and characterized using characteristic parameters obtained through micro-CT image analysis. The results were subsequently validated using field emission scanning electron microscopy imaging. Based on the observed trends, an interface model reflecting the fiber-matrix interface was proposed and compared with a perfect bond model to evaluate the differences in mechanical behavior. The model proposed in this study is a significant tool for material design. It addresses the current lack of methods for evaluating the microstructural properties of the fiber-matrix interface and investigating their correlation to FRCC mechanical behavior.