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Self-Compacting Concrete (SCC) is an innovative construction material that flows and compacts under its own weight, making it ideal for complex structures due to its high workability. Micro steel fibers, smaller in size than conventional fibers, have recently been adopted in both research and industry due to their limited effect on workability, which facilitates casting and construction process, alongside their promising contributions to enhancing the mechanical performance of concrete. The mechanical, rheological, and electrical properties of micro steel fiber-reinforced high-strength SCC members were investigated in this study. The testing program included prismatic specimens (100 × 100 x 500 mm3), cubic specimens (150 × 150 x 150 mm3), and cylindrical specimens (100 mm × 200 mm). The micro steel fiber contents considered were 0.0 %, 0.35 %, 0.70 %, and 1.05 % by volume. Test results revealed that the inclusion of micro steel fibers reduced workability, particularly above a 0.70 % fiber content, and resulted in maximum enhancement rates of 13.3 % in compressive strength, 52.4 % in splitting tensile strength, and 13.2 % in flexural strength compared to fiber-free specimens. The toughness index (T 150) was enhanced by up to 40 % at higher fiber volumes. These findings highlight the balance between workability and mechanical improvement provided by micro steel fibers. Bulk electrical resistivity exhibited a clear decreasing trend with increasing fiber content. • A detailed approach of producing high-strength self-compacting concrete was presented. • The impact of using different micro steel fiber contents was elucidated. • Straight micro steel fibers improved mechanical properties of concrete. • The electrical resistivity of micro steel fiber reinforced SCC was investigated. [ABSTRACT FROM AUTHOR]

Self-compacting concrete (SCC) is a particular type of concrete that flows and becomes consolidated under its own weight. Various have been conducted to enhance its performance. Key developments have been the addition of fibers and replacement of the mineral admixtures; several studies have focused on varying these factors in different proportions to produce a high performance concrete. However, there is no standard mix design for self-compacting concrete containing admixtures. Therefore, optimization of the mix design is very important in order to save time and to develop an economical SCC, but there has been no detailed study of mix design and optimization of materials, and no research into the alignment and orientation of the steel fibers. Along with the uniform dispersion of fibers, few steps have been taken to optimally align the micro steel fibers, with ultrasonic pulse velocity used to justify their distribution and alignment. These factors were taken into consideration in this study. The results show that the addition of steel fibers reduces the rheological properties of the concrete by 40%-55% compared to the control mix (MC1), although all the mixtures (MC1-MX4) justified the guidelines set by EFNARC (European Federation of National Association Representing for Concrete). All the specimens failed under shear. The addition of hooked-end micro steel increased the flexural strength compared to the control mixture and a 60% increase in MX4 and 75% increase in MA7 were observed compared to MC1. The fibers were aligned along the direction of flow and the alignment properties was justified by flexural strength and UPV. A regression equation was finally developed between flexural strength and UPV for future development, which predicts the behavior of micro steel fiber reinforced self-compacting concrete (MSFRSCC).

Steel fiber reinforced cementitious composites (SFRCC) have emerged as one of the most efficient techniques to improve the flexural capacity and ductility performance of concrete. However, one of the most significant shortcomings is the randomness of steel fibers direction in the concrete matrix, which influences the extent of mechanical enhancement for a limited fiber content. An experimental approach to control the direction of steel fibers embedded in self-compacting concrete is presented in this study, which is based on generating a driving rotating force to overcome the viscous impeding forces acting onto the embedded fiber. The mechanical performance of micro steel fiber reinforced self-compacting concrete members was investigated. A uniform magnetic field of 9.8 × 10−3 Tesla generated by a cylindrical powered coil was capable of aligning micro steel fibers embedded in fresh self-compacting concrete along the desired direction. The testing program included seven beam specimens of size of 100 × 100×500 mm3. The micro steel fiber contents considered were 0.35%, 0.70%, and 1.05% by volume. Fiber volume fraction of 0.35% was the optimum dosage for magnetic alignment as it achieved the highest extents of mechanical enhancement. The concrete specimens reinforced with 0.35% of steel fiber content have exhibited enhancement rates of 5%, 28%, and 30% in four-point failure load, maximum mid-span deflection, and compressive strength, respectively. Based on the visual analysis of cross-sectional images, the highest orientation factor achieved was 0.91 when steel fiber dosage was 0.35%, whereas the random non-magnetized steel fiber reinforced beams achieved an orientation factor ranging from 0.30 to 0.50. • A detailed approach of aligning steel fibers magnetically in concrete was presented. • Self-compacting concrete of low viscosity promoted a greater efficiency of alignment. • Magnetic alignment of embedded steel fibers improved the mechanical characteristics. • The impact of using different micro steel fiber contents was elucidated. • Detection of orientation factor confirmed the efficiency of magnetic alignment. [ABSTRACT FROM AUTHOR]

Self-compacting concrete (SCC) is a particular type of concrete that flows and becomes consolidated under its own weight. Various have been conducted to enhance its performance. Key developments have been the addition of fibers and replacement of the mineral admixtures; several studies have focused on varying these factors in different proportions to produce a high performance concrete. However, there is no standard mix design for self-compacting concrete containing admixtures. Therefore, optimization of the mix design is very important in order to save time and to develop an economical SCC, but there has been no detailed study of mix design and optimization of materials, and no research into the alignment and orientation of the steel fibers. Along with the uniform dispersion of fibers, few steps have been taken to optimally align the micro steel fibers, with ultrasonic pulse velocity used to justify their distribution and alignment. These factors were taken into consideration in this study. The results show that the addition of steel fibers reduces the rheological properties of the concrete by 40%-55% compared to the control mix (MC1), although all the mixtures (MC1-MX4) justified the guidelines set by EFNARC (European Federation of National Association Representing for Concrete). All the specimens failed under shear. The addition of hooked-end micro steel increased the flexural strength compared to the control mixture and a 60% increase in MX4 and 75% increase in MA7 were observed compared to MC1. The fibers were aligned along the direction of flow and the alignment properties was justified by flexural strength and UPV. A regression equation was finally developed between flexural strength and UPV for future development, which predicts the behavior of micro steel fiber reinforced self-compacting concrete (MSFRSCC). [ABSTRACT FROM AUTHOR]