# Special Issue on Advanced Fiber-Reinforced Cementitious Composites
## 3 Investigation of the Influence on Tensile and Electrical Properties by Steel Fibers  
The study conducted by [PERSON] et al. focuses on the development of multifunctional cement composites, specifically self-sensing cement composites. The incorporation of functional fillers, including steel fibers, nickel, and carbon, imparts conductive properties to the cement matrix. Carbon conductive fillers are reported to exhibit superior durability and conductivity. The research investigates the impact of carbon-based nanomaterials, such as graphite nanofibers, multi-walled carbon nanotubes (MWC-NTs), and graphene, on the electrical properties of cement paste [4]. [PERSON] et al. examine the electromechanical damage detection behavior of strain-hardened steel-fiber-reinforced cement composites (SH-SFRC) with six types of steel fibers. The electrical resistance of SH-SFRCs decreases with increasing tensile strain, indicating micro-crack formation. The investigated SH-SFRCs demonstrate higher gauge factors (50-140) compared to typical metals (around 2), indicating superior damage detection ability. T30/0.3 and T20/0.2 fibers exhibit the highest gauge factors, while S13/0.2 shows the highest electrical conductivity. These findings have significant implications for the development of multifunctional SH-SFRC for civil infrastructure [5]. [PERSON] et al. explore the feasibility of using hybrid polyethylene (PE) and steel fiber-reinforced-cement-composites (HY-FRCC) containing multi-walled carbon nanotubes (MWCNTs) as strain sensors. The proposed smart building material represents a novel multifunctional cement composite with structural and magnetic sensing capabilities. The results indicate the promising potential of cement-based sensors for structural health monitoring in civil infrastructure [6]. Overall, the research presented here demonstrates valuable contributions to the field of multifunctional cement composites and the utilization of various materials and fillers to enhance their properties. The studies provide detailed investigations into the electromechanical behavior and damage detection capabilities of different composites, shedding light on factors such as fiber type, electrical resistance, and gauge factors. The inclusion of carbon-based nanomaterials and the exploration of strain sensing in hybrid composites showcase the innovative nature of the research. However, a comprehensive assessment requires further analysis of experimental methodologies, statistical analyses, and potential limitations. Influence of Fiber Volume Fraction on Ultimate Strength and Failure Modes in UHPFRC Flexural Members  
[PERSON] et al. evaluate the ultimate strength of ultra-high-performance fiber-reinforced concrete (UHPFRC) flexural members. The study conducted an experimental program with fiber volume fraction, shear span to depth ratio, and compressive strength of matrix as the main variables. The inclusion of 2% volume fraction steel fiber increases the shear and flexural strength of UHPFRC beams significantly. The ultimate flexural strength and shear strength of UHPFRC members were evaluated using the current design code and UHPCC guidelines. The ultra-high strength concrete without steel fiber showed a shear failure. However, in specimens reinforced with steel fiber, the appearance and spread of diagonal cracks were observed. The applicability of two design recommendations was evaluated [7]. The tensile behavior of UHPFRC differs depending on the degree and direction of dispersion of steel fibers in the internal concrete matrix. In this study by [PERSON] et al.-the tensile behavior of the UHPFRC beam was investigated by comparing the analytical results of the moment-curvature curve with the experimental results. Three types of specimens were fabricated based on the design recommendations by incorporating two types of steel fibers at a volume ratio of 1.0% and 1.5%, respectively. The strength of the beams increased as the steel fiber content increased.