Steel Fiber Research Articles

Study on Seismic Performance of Steel Fiber Reinforced Concrete Pier Under Bending–Torsion Coupling

To systematically study the mechanical behavior of a steel fiber-reinforced concrete (SFRC) pier under bending–torsion coupling, three pier specimens with a clear height of 1200 mm, a diameter of 300 mm, and an SFRC height of 300 mm in the plastic hinge region were designed and fabricated. Quasi-static tests were carried out to observe the damage patterns and failure modes of the specimens. On this basis, multiple finite element models were established using the ABAQUS 2018 software to study the influence of the torsion–bending ratio and SFRC height on the seismic performance of the pier. The results show that the bending–torsion coupling effect leads to a decrease in the bending and torsion capacities of the pier. The presence of torque causes the plastic hinge position to move up and the plastic hinge area to expand. Adding SFRC at the bottom of the pier can effectively improve the bearing capacity of the pier under earthquake action. The optimal height of SFRC is half of the clear height of the pier under the common torsion–bending ratio, which can not only improve the seismic performance of the structure but also avoid material waste.

Effect of steel fiber and coal ash on the properties of dense bituminous macadam mixes of Indian Roads Congress grading II

Effect of steel fiber and coal ash on the properties of dense bituminous macadam mixes of Indian Roads Congress grading II

Effect of Steel Fibers in Compressive Strength of Concrete Cube and Cylinder Specimens

Research has shown that incorporating steel fibers into concrete effectively reduces its brittleness. When added in specific proportions, steel fibers enhance the compressive strength of concrete and help control cracking. This study aimed to assess and compare the variations in compressive strength between conventional concrete and steel fiber- reinforced concrete (SFRC) by introducing different percentages of steel fibers. Experimental investigations were conducted on concrete cylinders and cubes to evaluate the improvement in compression capacity and observe the load- deflection behavior of SFRC. To achieve this, SFRC specimens with fibers of an aspect ratio of 55 were prepared for both concentric and eccentric loading, alongside control specimens made of plain concrete. Their relative compression capacities were tested. Stone chips (20 mm) were used in the concrete mix, as the inclusion of steel fibers significantly enhances its compressive strength. The study specifically aimed to test the compressive strength of concrete cylinders and cubes with varying steel fiber content (0%, 0.3%, 0.5%, 1%, 1.5%, and 2% of the total concrete weight). The compressive strength of the specimens was measured at 3, 7, and 28 days. Additionally, various material tests were performed to assess material properties, and a slump test was conducted to evaluate concrete workability. The findings indicate that the compressive strength of SFRC cylinders and cubes increases with higher steel fiber content, and plain concrete exhibits lower strength compared to SFRC.

Formulation and characterization of steel fiber reinforced self-compacting concrete (SFRSCC) based on marble powder

Formulation and characterization of steel fiber reinforced self-compacting concrete (SFRSCC) based on marble powder

Synergistic Enhancement of High-Strength Concrete's Mechanical Strength Through the Utilization of Steel, Synthetic, and Hybrid Fiber Systems

This investigation addresses the notable gap in understanding the effects of fiber hybridization on concrete performance. The study's primary objective is to enhance the mechanical characteristics of high-strength concrete by incorporating a blend of steel and synthetic fibers. A detailed examination of 192 specimens, categorized into eight distinct groups, was conducted. This analysis focused on the roles of macrosteel and PP fibers in preventing significant cracks and micro-PVA and PP fibers in managing smaller-scale cracking. These specimens underwent stringent testing processes to evaluate the impact of fiber content, limited to a 1% concentration for macrofibers, on the compressive strength (CS) and flexural tensile (FTS) strength of the concrete. The results reveal that integrating steel fibers into concrete mixtures marginally enhances the CS (typically by 4–8%). In contrast, the incorporation of microsynthetic fibers (namely, PVA and PP), was observed to decrease the CS. This finding underscores the complexities inherent in the interaction between fibers and concrete. To support these findings, the study employed advanced nonlinear modeling techniques, concentrating on the interplay between various fiber types and their contributions to concrete strength. The developed models exhibit considerable predictive accuracy. The models showed the significant effect of macro-PP fibers on CS, especially when combined with steel fiber of length 40 mm. This specific blend produces a synergistic effect, notably enhancing the concrete's strength. Overall, this research provides crucial insights into the optimization of fiber-reinforced concrete mixtures, advancing the field by proposing enhanced mechanical performance strategies.

Dynamiczne właściwości fibrobetonu wytworzonego na bazie piasków odpadowych

The article presents the results of non-destructive testing of steel fiber reinforced concrete (SFRC) based on waste sand. Fiber concrete beams with different steel fiber content were subjected to two types of free vibrations: torsional and flexural vibrations. Based on the tests and Fourier analysis, the frequencies of these vibrations were determined. They were used to determine the dynamic modulus of elasticity (Young’s modulus), the dynamic shear modulus (modulus of rigidity) and the dynamic Poisson’s ratio. In the next stage, the influence of steel fibers on these parameters was determined. The tests have shown that the addition of steel fibers increases the value of dynamic modulus of elasticity and the dynamic shear modulus up to a certain critical fiber content, beyond which the values of these moduli decrease; moreover, steel fibers do not affect the value of the dynamic Poisson’s ratio.

Investigation into the deicing efficiency and self-healing capability of asphalt mixtures with aluminum dross powder and steel fiber

In winter, reduced friction between tires and icy roads increases accident risks. This study designs an asphalt mixture incorporating conductive waste materials aluminium dross powder (ADP) and steel fibre (SF) to accelerate ice removal. Under simulated −20 °C conditions, microwave heating is applied for 120 seconds to evaluate deicing efficiency. The results show that higher ADP and SF content increases the average surface temperature (AST) and ice-melting speed (IMS). The highest AST increased by 112.86%, while IMS improved by 73.6% compared to the reference sample. A linear relationship (R 2 = 0.91) is observed between ADP-SF content and microwave heating efficiency. For the Self-healing (SH) effect, an indirect tensile test (IDT) is performed before and after damage. Strength values and moisture susceptibility are also determined. Accordingly, higher ADP and SF content during 60 seconds of microwave heating enhanced healing, but after 120 seconds, increased SF content reduces healing effectiveness.

Influence of Test Configuration on the Bond–Slip Behavior of Hooked-End Steel Fibers in Concrete: Quantity, Inclination, and Spacing

The objective of this study is to assess the influence of test configuration on the pullout response of hooked-end steel fibers embedded in a cementitious matrix and to analyze how variations in quantity, inclination, and spacing affect discrete–explicit numerical simulations. The experimental campaign was conducted using dog-bone-shaped specimens with variables of number of fibers (one, two, and four), fiber inclination (0°, 15°, and 30°), and spacing (7 mm and 14 mm), with 133 specimens tested (19 per configuration). The results obtained showed that fiber inclination significantly influences pullout behavior, with higher inclinations (up to 30°) increasing pullout loads (PL1 and PL2 being the maximum pullout and the intermediate pullout load values, respectively) but also leading to fiber rupture in approximately 21% of cases. Closely spaced fibers (7 mm) demonstrated enhanced load transfer compared to wider spacing (14 mm), particularly in setups with multiple fibers. Increasing the number of fibers reduced variability in pullout results, providing more consistent data. Numerical simulations effectively capture fiber–matrix interactions, with load–CMOD curves generally aligning with experimental data. However, discrepancies in the fR1 parameter highlighted the need for further calibration to improve accuracy in modeling early cracking stages. These findings underscore the importance of fiber configuration in optimizing pullout performance and the potential for refining numerical models to better predict post-cracking behavior in steel fiber-reinforced concrete.

Fracture performance of ultra high performance concrete (UHPC) at different curing ages: experimental investigation and unified formulation

This study examines the fracture performance of Ultra-High Performance Concrete (UHPC) at various curing ages. Three-point bending tests on precast notched UHPC beams were conducted, considering different curing ages, steel fiber content, and coarse aggregate content. The analysis focused on failure mode, load-crack mouth opening displacement (CMOD) curves, peak load, fracture toughness, and fracture energy. Results showed that the aging process significantly impacts UHPC’s fracture performance, especially within the first 14 days of curing. The rate of improvement in fracture performance decreases after fiber inclusion, while the fracture performance shows a greater increase at earlier ages stages with the addition of coarse aggregate. Finally, a unified formula was proposed and validated for predicting the fracture performance index of UHPC at different curing ages. This research emphasizes the importance of material composition and curing time in enhancing UHPC’s structural integrity and safety during construction.

Retraction Note: Evaluating the impact of nano-silica on characteristics of self-compacting geopolymer concrete with waste tire steel fiber

Retraction Note: Evaluating the impact of nano-silica on characteristics of self-compacting geopolymer concrete with waste tire steel fiber

Long‐term mechanical properties of hybrid fiber‐reinforced engineered cementitious composite

AbstractHybrid fiber‐reinforced engineered cementitious composites (hybrid ECC) employing short straight polyethylene (PE) and steel fibers have attracted growing interest in engineering applications due to their superior strength and ductility. In most studies, the mechanical properties of hybrid ECC were determined based on samples cured for 28 days, while their long‐term mechanical properties are seldom studied. Since hybrid ECCs often incorporate supplementary cementitious materials that alter the hydration process over time, relying solely on the 28‐day strength of samples may lead to inaccurate structural designs. To better understand the long‐term mechanical properties of hybrid ECC, this work presents an experimental investigation of hybrid PE‐steel fiber‐reinforced ECC samples cured under standard conditions for up to 3 years. Uniaxial compressive tests, direct tensile tests, and four‐point bending tests were conducted with samples cured at standard conditions for 28 days, 1 year, and 3 years. It was found that the compressive and tensile strengths of hybrid ECC increased with age. However, as the age increased to 3 years, the ultimate tensile strain and flexural ductility decreased significantly by 54% and 35%, respectively, compared to their 28‐day values. Furthermore, most changes occurred within 1 year. It was also found that the main damage pattern of the PE fibers was transformed from pull‐out to rupture failure as the curing age increased. Thermal‐gravity analysis revealed that the hydration process of hybrid ECC may last for up to 3 years, which explains their changes in mechanical properties and PE fiber failure mode.

Use of AutoML platform for prediction of interface shear strength of reinforced concrete push-off tests

ABSTRACT This study utilises Exploratory 10.6, a coding-free machine learning (ML) platform, to predict the interface shear strength of concrete interfaces, offering a coding-free AutoML solution to a data-driven approach in structural engineering. A dataset of 200 push-off samples was analysed, incorporating six input parameters: volume fraction of steel fibres, concrete compressive strength, yield strength of interface reinforcement, strength ratio, interface shear reinforcement area, and interface shear plane area. The single output parameter is the interface shear strength. The study employed machine learning models, including XGBoost, decision tree (DT), random forest (RF), and linear regression (LR), to develop predictive models. XGBoost emerged as the most effective model, achieving an R2 of 0.924 and RMSE of 1.032, significantly outperforming traditional empirical models, such as those in AASHTO LRFD and ACI codes, which demonstrated poor generalisation across varying experimental conditions. The random forest and decision tree models achieved R2 values of 0.812 and 0.728, respectively, with RMSEs of 1.895 and 1.962, while the linear regression model showed the lowest performance with an R2 of 0.768 and an RMSE of 1.458. Data preprocessing techniques, including correlation plots and principal component analysis, highlighted strength ratio as the dominant factor influencing interface shear strength. This study also revealed that ML-based models performed better during training than testing, highlighting their reliance on training data. The findings underscore the superiority of advanced ML approaches, particularly XGBoost, over traditional empirical methods, and demonstrate the potential of coding-free platforms for enhancing predictive modelling in structural engineering.

Investigation on Shear Strength of Fiber Reinforced GPC Exposed to Elevated Temperatures

Investigation on Shear Strength of Fiber Reinforced <scp>GPC</scp> Exposed to Elevated Temperatures

Experimental Study on Bending Behaviors of Ultra-High-Performance Fiber-Reinforced Concrete Hollow-Core Slabs

Ultra-high-performance fiber-reinforced concrete (UHPFRC) has the characteristics of high strength, toughness, and excellent crack resistance. In order to fully utilize the high-strength properties of UHPFRC and reduce the structural weight and construction cost, solid slabs can be fabricated into hollow-core slabs or composite sandwich slabs. In order to further analyze the mechanical properties and mechanism of action of UHPFRC hollow-core slabs, one solid slab and two hollow-core slabs with the same geometric dimensions, reinforcement, and steel fiber volume content are designed in this paper, and their stress performance under a static load was investigated using a four-point bending test. The research results show that the UHPFRC hollow-core slab is anisotropic, and the bending stiffness of the section with parallel, distributed tubes is slightly smaller than that of the solid slab. The addition of steel fibers can greatly limit the development of cracks on a slab surface, so the elastic limit of a UHPFRC hollow slab is higher than that of a conventional concrete hollow slab. The whole bending process is roughly divided into the elastic stage, the elastic–plastic stage, and the plastic stage; the crack development process on the bottom of the slab can be classified into the cracking stage, the stable crack development stage, and the rapid propagation stage. In the elastic stage, the cross-sectional deformation of the UHPFRC hollow-core slab in the bending process still satisfies the assumption of a flat section. A row of parallel, round tubes on the neutral axis has a little effect on the cracking load, bearing capacity, and deformation capacity of the UHPFRC slab. By conducting the comparative analysis of the hollow rate and bearing capacity, when the hollow rate reaches 13.57%, the comprehensive weight of the solid slab is reduced by 13.16%, the cracking moment is slightly reduced, and the ultimate load is only reduced by 8.78%. Under the premise of meeting the bearing capacity, the hollow rate of the UHPFRC hollow-core slab can be appropriately increased to save money and energy.

Intelligent Proportion Optimization of SFRC Using Ensemble Learning: A Multi-Objective Predictive Framework

Steel fiber-reinforced concrete (SFRC) is formulated by incorporating short, slender steel fibers into standard concrete, thereby creating a composite material. This addition significantly mitigates the brittle nature of concrete, enhancing its strength, toughness, and durability. The application of SFRC not only improves structural safety and service life but also promotes the development of green building materials and efficient construction technologies. To optimize the mix proportion design of SFRC, key parameters such as steel fiber content, water, cement, sand, natural aggregates, and water reducer were collected. A neural network model was constructed to leverage its powerful nonlinear mapping capabilities, establishing an implicit relationship between the mix proportions and compressive strength. The trained model enables rapid prediction of SFRC compressive strength, while a genetic algorithm was employed to inversely search for the optimal mix proportions that meet target performance requirements, providing a novel approach and design strategy for the intelligent design of SFRC.

Enhancing Concrete Strength and Microstructure with Basalt and Steel Fibers in Acid and Base Environments Incorporating Desert Sand

Concrete is widely used in construction due to its remarkable compressive strength and durability. However, its performance can deteriorate when exposed to harsh environmental conditions, such as acidic or alkaline surroundings. There has been considerable interest in incorporating both basalt and steel fibers (B&SFs) to enhance the resilience of concrete in such challenging settings. This study presents a comprehensive examination of the influence of B&SFs on the strength and microstructure of concrete, utilizing desert sand as a fine aggregate and subjecting it to exposure to acidic and alkaline environments. Employing a systematic experimental approach, this research assesses concrete samples with varying B&SFs proportions. The study encompasses density and compressive strength tests, complemented by microstructural analyses using scanning electron microscopy (SEM) and X-ray diffraction (XRD), to analyze the performance of the concrete under diverse environmental conditions. Initial findings indicate that including B&SFs results in a substantial improvement in concrete strength. The role of basalt fibers (BFs) in enhancing the concrete's resistance to acidic environments by mitigating deleterious effects on microstructural integrity is particularly noteworthy. Notably, when exposed to acidic conditions, concrete mixtures containing 0.5% BFs demonstrated the least strength loss. When B&SFs are synergized, their positive effects are amplified, yielding concrete with exceptional resistance to alkaline environments. Microstructural analysis reveals that incorporating fibers refines and strengthens the interconnected matrix of cementitious products, thereby enhancing cohesion and overall strength. Furthermore, this study underscores that desert sand can be a viable alternative to traditional fine aggregates without compromising concrete resistance if it is appropriately reinforced with fibers. In conclusion, this research sheds light on the promising role of B&SFs in augmenting the strength and microstructure of concrete containing desert sand.

Steel fiber distribution and orientation in full-scale walls cast from FRC with various consistencies and casting procedures: evaluation by the inductive method

Steel fiber reinforced self compacting concrete has high potential application in structural elements. The distribution and orientation of fibers in fiber reinforced self compacting concrete play a key role in defining the mechanical and durability behavior. Several factors such as casting method and rheological properties of concrete may influence the fiber distribution and orientation within structural elements. In this paper, due to the importance of vertical elements and high uncertainties regarding fiber distribution and orientation in these elements, steel fiber dispersion and alignment were investigated. In this study, five structural walls (7.0 × 2.5 × 0.2 m) with three distinctive casting procedures (single point, double points, and continuous casting) and two rheological properties [self compacting concrete (SCC) and vibrated compacted concrete] were constructed. Thereafter, by using the inductive test, fiber orientation and distribution were assessed. The results indicated that using two casting points resulted in a more uniform fiber distribution. A comparison between the two SCC mix designs revealed that large coarse aggregates significantly increased segregation and scattering in fiber distribution and orientation. Additionally, fiber orientation analysis demonstrated that continuous casting and vibration led to greater fiber alignment in the horizontal direction. Finally, the results showed that the rheological behavior of concrete mix plays a major role in the fiber distribution compared to the casting procedure. Therefore, to achieve higher uniformity, altering mix designs is recommended.

Sustainable Strengthening of Concrete Using Lathe Waste Steel Fibers: Experimental and FEA Analysis

The construction industry is growing fast and increasing the demand for concrete which requires sustainable materials. Concrete is weak in tension and needs fiber reinforcement to improve strength. This study explores lathe waste steel fibers as a sustainable option to enhance tensile properties. Local industries produce large amounts of lathe waste that can be used in fiber-reinforced concrete. Traditional destructive testing is expensive and slow because it needs heavy machinery like Universal Testing Machines. This research combines destructive and computational analysis using ANSYS 15 for finite element modeling. Cylindrical and beam specimens were tested with fiber ratios from 0 to 3 percent. Results show that 2.5 percent fiber content gives the best compressive and flexural strength. Scanning electron microscopy confirms stronger bonding as fibers break within the matrix instead of pulling out. This study proves lathe waste steel fibers improve both performance and sustainability in construction

Experimental characterization of VHPC reinforced with short synthetic fibers

Very-High-Performance Concrete (VHPC) are defined as concrete capable of reaching compressive strength higher than 80 MPa. These performances can be reached thanks to its compact and extremely dense microstructure, as a result of a proper mix. Together with their great durability properties, these concretes may lead to reduce cross sections of structural elements and thus save material and built volumes. The addition of synthetic fibers allows to significantly increase the toughness and crack opening resistance, beyond the tensile strength. These benefits can easily be traduced in an improved durability of the VHPC concrete. the aim of this research activity is to enlarge the experimental database of high-performances concrete reinforced with synthetic fibers having different size. In fact, contrary to the case of steel fibers, few works are report ed in literature regarding the types of fibers investigated herein. In the present work three Very High-Performance Fiber Reinforced Concrete (VHPFRC) mixes have been studied and characterized in laboratory. The mixes were realized with the same VHPC concrete matrix and different types of synthetic fibers: 10 mm straight polyvinyl alcohol (PVA) fibers; 30 mm waved polypropylene (PP) fibers; 40 mm waved polypropylene (PP) fibers. The first mix was realized using PVA fibers only, the second with 30 mm PP fibers and the last one was obtained by mixing PVA fibers and 40 mm PP fibers. A further VHPC mix with no fibers has been also realized and tested as reference material. Compression tests on both cylindrical and cubic specimens and modulus of elasticity tests have been performed for each mix. The VHPFRC toughness have been determined by means of three-points bending tests according to EN 14651. The bending parameters obtained from the experimental test have been compared between all the mixes and an analysis of the fracture energy has been performed. Moreover, each mix has been tested at bending with four-points setup in order to verify the efficiency of this test type for VHPC reinforced with synthetic fiber. The results provided in the paper highlight the different effects, in terms of mechanical response, caused by fibers of different size at different cracking stages of the tested materials.

Effect of single and hybrid incorporation of steel, polypropylene and polyethylene terephthalate fibres on the properties of concrete under static and impact loading

The effects of single and hybrid use of steel fibres (STF), polypropylene fibres (PPF) and polyethylene terephthalate fibres (PETF) on the static and impact properties of concrete were comprehensively evaluated. The concretes were evaluated and compared according to different properties, including static properties (unit weight, compressive strength, flexural strength, splitting tensile strength, fracture energy and flexural toughness), microstructural properties, impact performance and cost. In addition, the overall performances of the tested mixtures were comparatively assessed using desirability function (DF) analysis. The performed tests and analyses showed that STF had a positive effect on the compressive strength of concrete, the PPF and PETF had a negative effect. On the other hand, the fibres, especially STF, led to remarkable increases in the splitting tensile strength, flexural strength, flexural toughness, fracture energy and impact performance of the concrete. It was found that under static and impact loads, fibres were successful at shifting the brittle behaviour of concrete into more ductile behaviour. Scanning electron microscopy analysis revealed that the STF had better adherence with the surrounding cement paste than the PPF and PETF. It was concluded from the DF analysis that concrete containing 1% STF showed the best overall performance of all the tested concrete mixtures.