Enhanced impregnation quality, interfacial bonding, and mechanical performance of cementitious mineral-impregnated carbon fiber reinforcements through tailored fiber sizing

Abstract

The rising demand for sustainable and high-performance materials in construction has driven the advancement of mineral-impregnated carbon fiber composites, offering an innovative alternative to traditional fiber-reinforced polymer systems. This study evaluates the role of fiber sizing agents—thermoplastic, epoxy, and vinyl ester—on the interfacial properties, impregnation efficiency, and mechanical performance of cement based mineral-impregnated carbon fibers. Using an automated pultrusion process, carbon rovings were impregnated with a cementitious matrix and analyzed through multiscale characterization techniques, including wettability assessments, interfacial shear strength measurements, morphological analysis, and comprehensive mechanical testing. Vinyl ester-sized fibers exhibited superior wettability with water and cementitious materials, along with enhanced impregnation efficiency, resulting in a 62 % improvement in flexural strength and a 14 % increase in tensile strength compared to unsized fibers. In contrast, unsized fibers demonstrated limited wettability, higher porosity, and weak interfacial adhesion, leading to lower mechanical performance and greater variability. Thermoplastic- and epoxy-sized fibers produced intermediate results, highlighting the importance of optimized sizing formulations. Statistical modeling using Weibull analysis confirmed the enhanced reliability and consistency of mineral-impregnated, differently sized carbon fibers. This work underscores the pivotal role of fiber sizing in improving the performance and scalability of mineral-impregnated carbon fibers, establishing a foundation for the development of sustainable, high-performance materials for modern construction applications.