Steel Fiber Reinforced Cementitious Composite Research Articles

Research on Flexural Properties and Flexural Toughness Evaluation Method of Steel Fiber Reinforced Cementitious Composites under Polar Low Temperatures

In this research, five groups of steel fiber reinforced cementitious composite (SFRCC) with different fiber volume content (0%, 0.5%, 1.0% 1.5%, and 2.0%) were designed to perform four-point flexural tests on beam specimens to study the effects of polar temperature (20, 0, −25, −50, −75, and −100°C) and fiber volume content on the flexural properties. The flexural toughness index and load holding capacity index were calculated based on the load–displacement curve, and the enhancement and toughening mechanisms of SFRCC by low temperature and steel fibers were analyzed in conjunction with experimental observations. The results of the proposed flexural toughness evaluation method show that the flexural toughness of SFRCC can significantly improve than that of ambient temperature when the temperature is lower than 0°C. With the decrease in temperature, the flexural property of SFRCC increases first and then decreases, and the temperature point of this transition is around −50–−75°C. The flexural property enhancement effect of 1.0% fiber volume content SFRCC is more significant in low temperatures according to the flexural toughness index and load holding capacity index. The conclusion can provide a reference for the application of SFRCC in cryogenic engineering, as well as a simple and quantifier evaluation method for flexural toughness is proposed.

Prediction models of compressive mechanical properties of steel fiber-reinforced cementitious composites (SFRCC)

Steel fiber reinforced cementitious composites (SFRCCs), including normal strength concrete (NSC), high strength concrete (HSC), and ultra-high performance concrete (UHPC), have attracted significant attention in research and commercial applications due to their excellent mechanical properties and durability. The compressive performance of concrete reflects the maximum stress that the material can withstand under applied loading, which directly affects the safety and bearing capacity of buildings and is a very important parameter in the design and construction of buildings. Many researchers have experimentally studied the mechanical properties of SFRCC under uniaxial compression and proposed models to predict the compressive properties, such as compressive strength, elastic modulus, and peak strain. However, the test results and quantitative assessment of the existing models in the literature indicate that the goodness of fit of existing models is not well enough. Even under their specific range given in the respective studies, the maximum values of correlation coefficient in regression analysis, R2, are 14.5 % for compressive strength, 36.0 % for elastic modulus, and 42.1 % for peak strain. In addition, the scope of application is not wide enough as soon as the influencing factors considered are not sufficient. This makes that the compressive properties of SFRCC cannot be accurately predicted. In order to overcome these limitations, compression tests on UHPC were conducted in this study, focusing on the most commonly used straight steel fibers (13 mm long and 0.2 mm diameter). Further, modified models for predicting compressive properties were proposed using test data from this study and existing publications, with the R2 of 46.7 % for compressive strength, 48.1 % for elastic modulus, and 48.4 % for peak strain. The new models showed higher accuracy and applicability in predicting SFRCC compressive properties.

Magnetic Alignment of Micro Steel Fibers Embedded in Self-Compacting Concrete

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 x 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.

Optimization of the Shape of Hooked-End Steel Fiber Based on Pulling Out and Reinforcing Cementitious Composites.

Efficient steel fiber-reinforced cementitious composites (SFRCC) should improve not only the ultimate tensile strength but also the residual tensile strength (post-cracking tensile strength) of the SFRCC matrix. The degradation of the post-cracking tensile strength of SFRCC depends on the pullout properties of the steel fibers from the cementitious matrix. When the straight steel fiber was pulled out from the matrix, the pullout resistance was affected by the actions of bonding and friction. After debonding, the load was transferred only by friction, and the pullout resistance decreased rapidly, resulting in a weak reinforcing effect. In addition, changing the fiber shape can effectively slow down the decreasing rate of the pullout resistance of the steel fibers, thus improving their reinforcing effects. In this study, the shape of the steel fibers was optimized to slow down the decrease in the pullout resistance of the steel fibers from the cementitious matrix, thus achieving better tensile properties of SFRCC. First, a calculation model for the steel fiber pullout resistance was established. On this basis, a method to optimize the shape of the steel fibers was proposed. Finally, the pulling out behavior of steel fibers with different end hook shapes was tested, and the influence of the steel fiber shape on the decreasing rate of the residual pullout resistance was analyzed. The results showed that the optimized hooked-end steel fibers had better pullout resistance than ordinary hooked end steel fibers of the same diameter, tensile strength, and matrix.

Investigation on the performance of annularly aligned steel fiber reinforced cementitious composites pipe under internal water pressure

Steel fiber reinforced concrete pipes are commonly used in the municipal, agricultural, and industrial fields because of their superior internal water pressure performance. However, the randomly distributed steel fibers hinder the further improvement of internal water pressure performance. To maximise the reinforcement effect of steel fibers and improve the internal water pressure performance, an external circular magnetic field was first utilised to prepare annularly aligned steel fiber reinforced cementitious composite (AASFRC) pipes in which the steel fibers were aligned in the direction of tensile stress. Subsequently, the internal water pressure performance of AASFRC and steel fiber reinforced cementitious composite (SFRC) pipes was experimentally and numerically investigated. Finally, the reinforcement mechanism of the annularly aligned steel fibers was revealed from the aspects of fiber distribution and fiber resultant force. The results showed that the deformation and bearing capacity were enhanced by annularly aligned steel fibers. The ultimate internal water pressure of the AASFRC pipes was greater than that of the SFRC pipes by 22–32% with fiber volume fractions (Vf) of 0.8%, 1.2%, and 1.6%, implying that using less fiber in AASFRC pipes can ensure an internal water pressure performance equivalent to that of SFRC pipes. Both the fiber orientation efficiency factor and number of fibers bridging the principal cracking section of the AASFRC pipes were greater than those of the SFRC pipes. The fiber resultant force of AASFRC specimens was 2.04–2.64 times greater than that of SFRC, contributing to the enhancement in the bearing capacity of AASFRC pipes.

Mechanical properties of a 3D-printed SFRC beam with steel fiber distribution adaptive to tensile stress

To maximize the reinforcement of steel fiber in the steel fiber reinforced cementitious composite (SFRC) simply supported beam subjected to concentrated load at the midspan, the steel fiber is distributed according to the magnitude and direction of the tensile stress at the section of the midspan, which is defined as the adaptively distributed steel fiber reinforced cementitious composite (DD-SFRC) beam. In the DD-SFRC specimens, the dosage of steel fiber increases with the magnitude of the tensile stress and the orientation of steel fibers is parallel to the direction of tensile stress. In the preparation of the DD-SFRC beams, the distribution density and orientation of steel fibers were controlled by 3D printing and magnetic field, respectively. The mechanical properties of the beam were investigated by three-point bending tests and compared with the beams with aligned (AD-SFRC) or random (RD-SFRC) steel fiber distribution. The results showed that the mechanical properties of the beam are significantly improved by the adaptive distribution of steel fibers.

A Comparative Study on Electrical Resistivity and Compressive Strength Properties of Cement Composites Incorporating Conductive Materials

Conductive cement composites have attracted high attention in recent years due to the possibility of achieving multifunctional materials. The usual approach has been to incorporate steel fiber, carbon fiber, graphite, and carbon nanotube/or carbon nanofiber into the cement matrix. In this article, an experimental comparative study was conducted on the electrical resistivity and compressive strength properties of cement composites incorporating carbon fiber (CF) and steel fiber (SF), which are conductive materials. The electrical resistivity of the conductive fiber-reinforced cement composites (FRCCs) was measured using the four-probe method, and compressive strength was conducted based on the KS L ISO 679 and ASTMC109/C109M test methods. Their performance was compared and analyzed with plain cement composites (PCCs). Afterwards, the fracture surfaces of the conductive SFRCCs (steel fiber-reinforced cement composites) and CFRCCs (carbon fiber-reinforced cement composites) were also analyzed using a scanning electron microscope (SEM). The experimental results showed that, in all specimens, the electrical resistivity gradually increased as the curing ages elapsed, while the electrical resistivity decreased significantly as the fiber volume fractions increased. Overall, the addition of SF up to a fiber volume fraction of 1.25% did not significantly affect the electrical resistivity of cement composites. In contrast, however, the electrical resistivity of CF decreased slightly even at a low dosage (i.e., 0.1–0.3%), and thereafter, it was significantly decreased. The percolation threshold of the conductive CFRCC incorporating CF used in this experiment was 0.4%, and this seemed to be the optimal CF dosage that can greatly improve the conductive cement composites while maintaining the maximum performance of compressive strength. In addition, the compressive strength of conductive SFRCC was higher than that of PCC, whereas in the case of conductive CFRCC, it showed a greater tendency to decrease significantly as the fiber volume fractions increased. We expect the results of SEM image analysis to be useful as basic data for establishing microstructure mechanisms of reinforcement fibers in the cement matrix.

Flexural Behavior Characteristics of Steel Tubes Filled with SFRCCs Incorporating Recycled Materials.

This study deals with the effect of fly ash and recycled sand on the flexural behavior of SFRCCs (steel fiber-reinforced cementitious composites)-filled steel tubes. As a result of the compressive test, the elastic modulus was reduced by the addition of micro steel fiber, and the fly ash and recycled sand replacement decreased the elastic modulus and increased the Poisson's ratio. As a result of the bending and direct tensile tests, strength enhancement by the incorporation of micro steel fibers was observed, and a smooth descending curve was confirmed after initial cracking. As a result of the flexural test on the FRCC-filled steel tube, the peak load of all specimens was similar, and the applicability of the equation presented by AISC was high. The deformation capacity of the steel tube filled with SFRCCs was slightly improved. As the elastic modulus of the FRCC material lowered and the Poisson's ratio increased, the denting depth of the test specimen deepened. This is believed to be due to the large deformation of the cementitious composite material under local pressure due to the low elastic modulus. From the results of the deformation capacities of the FRCC-filled steel tubes, it was confirmed that the contribution of indentation to the energy dissipation capacity of steel tubes filled with SFRCCs was high. From the comparison of the strain values of the steel tubes, in the steel tube filled with SFRCC incorporating recycled materials, the damage was properly distributed between the loading point and both ends through crack dispersion, and consequently, rapid curvature changes did not occur at both ends.

Preparation and fracture behavior of annularly aligned steel fiber reinforced cementitious composite: Experiment and simulation

Annularly cement-based structures are widely used in the harsh environments, such as municipal drainage and subway tunnels. The cracks in the structures will provide the penetrate channel of aggressive media, which induces the further deterioration. To prevent cracking and improve durability, an external circular magnetic field is applied in this work to prepare the annularly aligned steel fiber reinforced cementitious composites (ASFRC). The fracture behavior of annularly ASFRC is investigated by three-point bending fracture test. Moreover, the fracture propagation progress is elucidated based on the digital image correlation (DIC) approach. The results reveal that the initial fracture toughness (Kini) and fracture energy (GF) of annularly ASFRC arch notched beams are improved by more than 35% and 100%, respectively, when compared to the steel fiber reinforced cementitious composite (SFRC) with randomly distributed fibers. The development of the strain field produced by the DIC method also demonstrates that aligning steel fibers improves the crack resistance of arch notched beams greatly. Moreover, the effects of steel fiber volume fraction and initial notch ratio on fracture behavior of arch notched beams are further verified and measured based on numerical simulation method. This study can provide guidance for the application and promotion of annularly ASFRC.

Utilization of novel stranded steel fiber to enhance fiber–matrix interface of cementitious composites

Reinforced materials with helically twisted geometries have been successfully applied in the concrete structures, owing to their superior mechanical properties and anchoring capabilities. Helically twisted types materials with diameters less than 1.0 mm might be an ideal type of fiber for cement-based materials reinforcing. In this article, a novel stranded steel (SS) fiber was first proposed and realized by simply cutting the commercial steel strands. The fiber–matrix interfacial properties and mechanical performance of steel fiber reinforced cementitious composites (SFRCC) were investigated. It was found that the SS fiber-cement matrix interface demonstrated superior interfacial bonding performance, as compared to those for the interface between hooked-end/straight fibers and cement matrix. For the mechanical properties of SFRCC, cementitious composites reinforced by SS fiber exhibited strikingly outstanding mechanical property as any other types of steel fiber with the same fiber amount. In conclusion, SS fiber may be more suitable for cementitious composite reinforcement than hooked-end and straight fibers.

Experimental and Numerical Evaluation on the Performance of Perfobond Leiste Shear Connectors in Steel-SFRCC Composite Beams.

The difference between the shear performances of Perfobond Leiste (PBL) shear connectors embedded in steel fiber-reinforced cementitious composite (SFRCC) structure and normal strength concrete (NC) structure was investigated by push-out tests and finite element (FE) simulations. Push-out tests were carried out on nine steel-SFRCC specimens and nine steel-NC specimens. The mechanical behavior of the PBL shear connector was examined according to the failure modes, load-slip curves, and strain distribution laws of the push-out specimens. Experimental results revealed that the extension of cracks in SFRCC was hindered by steel fibers, and the number and width of cracks in SFRCC were smaller than those in NC. The failure mode of the steel-SFRCC specimens and the single-hole steel-NC specimens was the shear failure of the penetrating reinforcement, whereas that of the multi-hole NC specimens was concrete slab cracking. The ultimate shear bearing capacity of PBL shear connectors in the steel-SFRCC specimens was 47.8% greater than that in the steel-NC specimens. Furthermore, an FE model verified by the test results was established to conduct parametric analyses. It was found that the hole diameter and thickness of the steel plate and the yield strength of the penetrating rebar greatly affected the shear bearing capacity of PBL shear connectors. Finally, based on the experimental and FE simulation results, an expression for calculating the ultimate shear bearing capacity of PBL shear connectors in the steel-SFRCC composite structure was developed by considering the bearing effects of concrete dowels, penetrating rebars, and end parts.

A micromechanical crack bridging model considering the slip-softening interface with the residual shear stress for SFRCC

Characterizing the bond properties of the steel fiber/matrix interface plays an important role in describing the crack bridging effect in steel fiber-reinforced cementitious composites (SFRCC). In this paper, a new interface law considering the residual shear stress is proposed to interpret the slip-softening effects of the steel fiber/matrix interface. Accordingly, a micromechanical crack bridging model for SFRCC is formulated by combining the single steel fiber pullout model with the image analysis-based fiber orientation distribution. Comparisons with the experimental data and the existing models show that the proposed model can well predict SFRCC’s tensile softening behavior. Meanwhile, the decrease rate of the bridging stress, the composite fracture energy, the peak bridging stress and the corresponding peak crack opening displacement (COD) are employed to quantitatively evaluate the crack bridging curves. Finally, the effects of the residual shear stress ratio, the interfacial softening coefficient and the fiber orientation distribution on the crack bridging relation are discussed with the proposed framework.

Experimental and Numerical Analyses of Stud Shear Connectors in Steel-SFRCC Composite Beams.

To investigate the shear performance and failure mechanism of stud shear connectors in steel fiber-reinforced cementitious composite (SFRCC) beams, six steel-SFRCC and six steel-normal strength concrete (NC) push-out specimens with two heights (80 mm, 120 mm) and three diameters (14 mm, 18 mm, 22 mm) of stud connectors were prepared. The experimental results revealed that the stud shearing failure was the main failure mode of all push-out specimens. In comparison to the steel-NC specimens, the development of cracks in the SFRCC beams was efficiently restrained due to the existence of high-strength steel fibers added to the normal concrete. The shear resistance and stiffness of studs in the steel-SFRCC beams were, respectively, 22.3% and 15.1% greater than those in the steel-NC specimens; however, their ductility was reduced, and the stud shear connectors failed in advance. The finite element (FE) model was developed and verified by push-out test results. FE analysis results indicated that the shear resistance of stud shear connectors was significantly improved with the increase in the concrete compressive strength, the stud diameter and tensile strength, whereas the aspect ratio of studs had a small impact on the ultimate resistance of stud shear connectors. Based on the as-obtained push-out experiment and FE analysis results, empirical formulas were presented to predict the load-slip curves and ultimate shear resistance of stud shear connectors in the steel-SFRCC specimens, and higher accuracy and a wider application range were obtained than with previous formulas.

An integrated experimental and multiscale numerical methodology for modeling pullout of hooked-end steel fiber from cementitious matrix

This work proposes a methodology to translate the experimental pullout results of hooked-end steel fibers from cementitious matrix to a multiscale model with a discrete and explicit representation of steel fibers. The coupling scheme of non-matching meshes used to describe the fiber–matrix interaction is adapted to represent separately and explicitly the anchorage mechanism of hooked-end steel fibers. The difference of the experimental results of pullout tests of hooked-end steel fibers (DramixⓇ 80/60 BN) and straight fibers obtained by cutting the hooked-ends of the fibers is used as input parameters to describe the anchorage mechanism. Pullout tests with one and four fibers aligned to the applied loading and perpendicular to the crack plane are carried out to investigate the effect of instability on the experimental results. The methodology is also coupled with an analytical model for predicting the effect of fibers inclined to the crack surface. Initially, the effect to represent explicitly the anchorage of hooked-end steel fibers in multiscale models is assessed through the simulation of pullout tests. Then, the numerical model is applied to obtain the post-cracking parameters of steel fiber reinforced cementitious composites (SFRCC) through the simulation of flexural three-point-bending test (3-PBT) according to EN 14651, considering the same type of hooked-end steel fibers and a similar matrix strength. Thus, the bond–slip model derived from pullout tests is used together with the amount and orientation of steel fibers obtained from the inductive test carried out. The results demonstrate that the integrated experimental and multiscale methodology may be very useful to link the physical and numerical responses of SFRCC with hooked-end steel fibers, and the numerical tool obtained can contribute for better understanding the failure processes for this type of composite.

Machine learning prediction of structural response of steel fiber-reinforced concrete beams subjected to far-field blast loading

Owing to its superior mechanical properties, enhanced energy absorption, and improved blast resistance, steel fiber-reinforced cementitious composites are a prime choice for the development of resilient structures. Sizable advancements have recently been made in assessing the blast performance of steel fiber-reinforced concrete (SFRC), high-strength steel fiber-reinforced concrete (HSFRC), and ultra-high-performance steel fiber-reinforced concrete (UHPFRC). However, there is still need for concerted research to explore the effects of fiber parameters under blast loading and to develop simple and robust predictive models. Thus, the present study develops a machine learning model to predict the maximum displacement of SFRC, HSFRC, and UHPFRC beams subjected to far field blast loading. Using Gaussian Process (GP) regression and Conditional Tabular Generative Adversarial Networks, a novel model was developed considering 117 experimental and 300 synthetic datasets. The proposed model was appraised through several statistical performance metrics and compared to existing analytical and numerical methods. The model imparts noteworthy reduction in modeling complexity in terms of static and dynamic material properties. A parametric analysis was conducted using the developed model to investigate the effects of fiber properties for diverse beam configurations. The proposed simplified model achieved highly favorable predictive performance with MAE of 2.75, R2 of 90.32%, and MAPE of 13.8%.

Complex Permittivity Measurements of Steel Fiber-Reinforced Cementitious Composites Using a Free-Space Reflection Method with a Focused Beam Lens Horn Antenna.

To measure the electromagnetic properties of steel fiber-reinforced concrete (SFRC) in the X-band, 1-port measurements were performed using a lens horn antenna in a free-space measurement system. Free-space 1-port calibration with translations of the position of the reflector regarding the characteristics of the focused beam lens horn antenna was applied. The intrinsic impedance and complex permittivity of the SFRC were obtained from the measured reflection characteristics. The steel fiber content increased and the electromagnetic properties of the SFRC gradually changed from a dielectric to a conductor, even in very low frequencies compared to the plasma frequencies of general metal, which are optical frequencies. This is considered to be the plasmon effect of the metallic structure formed by the steel fiber. This result is applicable for analyses of the electromagnetic phenomenon of large structures with fiber content.

Interfacial technology for enhancement in steel fiber reinforced cementitious composite from nano to macroscale

Abstract The rapid construction of innovative structures and megastructures is pushing the development of steel fiber reinforced cementitious composite (SFRCC). The interfacial enhancement technology from nano to macroscale for improving global properties of SFRCC is summarized here, including nanomaterials reinforcement of cementitious matrix, physical arrangement and nanomaterials modification of steel fiber. The interfacial bonding strength of SFRCC can be enhanced more than 150% via these approaches. To evaluate the effect of local interfacial technology on global mechanical properties of SFRCC, the structural performance of SFRCC with interfacial modification is reviewed. The energy absorption capacity of SFRCC can be improved over 20% through interfacial enhancement technology. The multi-scale mechanisms behind these approaches are illustrated through macroscale characterizations and molecular dynamics modeling. Furthermore, the key challenges and future prospects of enhancement approaches are also discussed from the perspectives of bottom-up system, nanoscale reinforcement, and durability properties in SFRCC, which are expected to inspire further improvement in interfacial performance and promote the application of SFRCC in practical engineering.

Investigation of mixed-mode fracture of aligned steel fibre reinforced cementitious composites

Mixed-mode fracture experiments were conducted on aligned steel fibre reinforced cementitious composite (ASFRC) and ordinary steel fibre reinforced cementitious composite (SFRC) three-point bending beams. Mixed-mode fracture performances of the ASFRC and SFRC specimens were studied by changing the crack offset distance. The fracture processes of the ASFRC and SFRC specimens were simulated using the extended finite element method. A good agreement was found when the simulation results were compared with the experimental ones. The alignment of steel fibres significantly improved mixed-mode fracture properties. The peak load $$P_{\mathrm {max}}$$ and crack initiation angle of the ASFRC specimen were obviously greater than those of the SFRC specimen because more steel fibres bridged the crack. Compared to the SFRC, the $$P_{\mathrm {max}}$$ of the ASFRC increased by 58%, 49% and 38% with the crack offset distances of 0, 50 and 100 mm, respectively. The crack initiation angle of the ASFRC increased by 11% and 17% with the crack offset distances of 50 and 100 mm, respectively. In addition, the influences of the initial crack length to depth ratios a/D and the steel fibre volume fraction $$V_{\mathrm {f}}$$ on the ASFRC specimens were simulated. The $$P_{\mathrm {max}}$$ significantly increased with $$V_{\mathrm {f}}$$ and decreased with a/D

Design, preparation and mechanical properties of full-field aligned steel fiber reinforced cementitious composite

In this study, a full-field aligned steel fiber reinforced cementitious composites (FASFRC) prism specimen was designed, prepared and tested. The special feature of the FASFRC is the orientation of steel fibers in the specimen is consistent with the principal stress when apply flexural loading to the specimen. In order to optimise the design of the FASFRC prism, the orientation of the major principal stress of the prism subjected to flexural load was determined by finite element analysis, which is the expected orientation of steel fibers in a true specimen. Then, in the preparation of the FASFRC prisms, an external magnetic field with magnetic line consisting with the direction of the principal stress was used to control the direction of steel fibers to be consistent with the designed orientation when the mixtures were compacted. Finally, the flexural strength, toughness and residual strength of FASFRC, conventional steel fiber reinforced cementitious composite (SFRC) and aligned steel fiber reinforced cementitious composite (ASFRC) prism specimens were tested by four-point bending tests. Through the tests, it is found that the mechanical properties of the FASFRC specimens were significantly higher than other specimens mainly due to the enhancement of the reinforcement of steel fibers.

Understanding the Toughening Mechanism of Silane Coupling Agents in the Interfacial Bonding in Steel Fiber-Reinforced Cementitious Composites.

Interfacial bonding between a fiber and a matrix plays an essential role in composites, especially in fiber-reinforced cementitious composites that are superior forms for bearing flexural and tension load in construction applications. Yet, despite the importance, effective and economic approaches to improve the interfacial bonding between a steel fiber and a cementitious matrix remain unfeasible. Herein, we report a pathway adopting a silane coupling agent (SCA) to modify an interfacial transition zone (ITZ) and enhance interfacial bonding. This approach involves coating a SCA layer onto a steel fiber, where tight physical and chemical bondings (via cross-linking of silicate chains) with a cementitious matrix are formed, leading to an 83.5% increase in pullout energy. Combining nanoindentation and an atomistic force microscope with molecular simulation, we find that SCA increases the surface roughness of the steel fiber, accelerates the hydration reaction of cement clinker, and promotes the volume fraction of the C-S-H phase, inducing a denser and more uniform ITZ with an adequate stress-transfer capability that shifts the mode of failure from interfacial debonding to cement cracking. This work presents an effective and economical approach to improve interfacial bonding, and it enables us to design more durable fiber-reinforced cementitious composites, which can be massively used to build innovative infrastructures.