Enhancing spalling resistance and mechanical properties of ultra-high performance concrete at elevated temperatures using hybrid polyoxymethylene and steel fibers

Dynamic tensile behavior of ultra-high performance concrete reinforced with steel fibers under quasistatic to high strain rates

Study on damage characteristics of early-age steel fiber shotcrete under high-temperature variable-temperature curing and cyclic impact loading

Low-temperature climate in extremely cold regions can pose significant challenges to the durability of concrete. In this study, artificially simulated chloride dry–wet cycle tests were performed on 25 groups of steel fiber–reinforced rubberized concrete (SFRRC) cubic specimens, which were subjected to low temperatures (0°C, −20°C, −40°C, and −60°C) to ambient temperature (20°C) cycling. Additionally, 50 groups of plain concrete (PC) and rubberized concrete (RC) cubic specimens subjected to the same treatment were provided as controls. The distribution of free chloride content within the PC, RC, and SFRRC specimens was measured and determined. Three key parameters (convection zone depth, peak free chloride content, and chloride diffusion coefficient) for evaluating chloride erosion resistance of SFRRC were calculated. Furthermore, a time-dependent predictive model for the free chloride content in SFRRC was developed, taking into account the effects of low temperatures. The experimental results indicated that the chloride erosion resistance of PC and RC were negatively impacted by the effect of low temperatures. However, the incorporation of steel fibers can effectively mitigate the adverse effects of low temperatures on the chloride erosion resistance of SFRRC, resulting in reductions of 10.6%, 14.3%, and 13.9% in convection zone depth, peak free chloride content, and chloride diffusion coefficient, respectively, compared to RC. The proposed model in this study can provide accurate predictions of the chloride erosion resistance of SFRRC in extremely cold regions.

Analytical model for pullout behavior of novel multiple hooked-end steel fiber in cementitious matrix

Capture of polonium homologue tellurium via silver nanoparticle decorated stainless steel fiber felt

Durability and microstructural behavior of high-strength concrete incorporating recycled steel fibers and ultrafine palm oil fuel ash under acidic and sulfate exposure

Hybrid steel–PVA fiber-reinforced concrete offers promise for enhancing both load-bearing capacity and deformation capacity. However, the coupled effects of fiber parameters and volume-fraction combinations on compressive strength (σc) and peak strain (εc) are still not fully understood. A unified, interpretable, and engineering-oriented quantitative framework is still lacking. This study compiled experimental data from 26 published literature, building a multi-source database consisting of 397 datasets for σc and 203 datasets for εc. Based on this database, a comprehensive analytical framework was proposed, including model prediction, SHAP-based interpretation, Monte Carlo marginalization, synergy-gain window determination, and dual-objective mix-proportion optimization. For σc prediction, LightGBM achieved the highest test-set R2 (0.9783), whereas CatBoost showed more robust error control (MAE = 2.7409 MPa). CatBoost was therefore selected as the base model for the subsequent interpretation analysis. For εc prediction, Bayesian-optimized CatBoost achieved the best test performance (R2 = 0.9659, MAE = 0.0218, RMSE = 0.0358), while the transfer-learning model reached a comparable accuracy level (R2 = 0.9650). SHAP analysis revealed that σc is mainly governed by matrix mix-proportion factors and steel fiber volume fraction, whereas εc is more sensitive to S/B and PVA-related variables. The mean synergy-gain maps generated via Monte Carlo marginalization and two-dimensional grid evaluation further showed clear differences between the two targets. Positive synergy in σc was highly localized. Its maximum mean synergy gain was 4.7949 MPa at (Steel, PVA) = (1.875%, 2.000%). By contrast, εc exhibited a wider positive-synergy region, with a peak value of 0.0141629 at (0.38%, 1.62%). Therefore, the engineering output of this study is not a single optimal mix point. Instead, it is a set of candidate windows for different performance targets, together with boundary-risk identification and priorities for experimental validation.

The project focuses on enhancing the performance of Fibre Reinforced Concrete (FRC) through the partial replacement of cement with industrial by-products and the inclusion of steel fibres. Cement production is a major source of CO₂ emissions, necessitating the exploration of sustainable alternatives. This study utilizes Fly Ash and Silica Fume as partial cement replacements to improve the long-term strength and durability of concrete, while incorporating steel fibres to enhance it tensile strength, ductility, and crack resistance. The concrete mixes will be tested for compressive strength, split tensile strength, and flexural strength at 7, 14, and 28 days. A comparison of strength gain over these periods will be made to determine the optimum mix proportion that balances sustainability and mechanical performance. The scope includes testing various percentages of cement replacement and steel fibre volumes to formulate a high-performance, eco-friendly concrete mix.

Steel fiber (SF) cement mortar, renowned for its dual advantages of strength and toughness, is widely used in construction, transportation, and other engineering fields. However, in actual service, it often faces challenges, such as weak bonding at the SF-cement matrix interface and insufficient freeze resistance in severe cold environments, which compromise the long-term durability of engineering structures. To optimize the performance of SF cement mortar, a composite cement mortar (TS) was developed. This study investigates the effects of single-blending nano-TiC(NT), nano-CaCO 3 (NC), and their combined blending on the mechanical properties (flexural and compressive strength) and freeze-thaw resistance (mass and strength loss rates under freeze-thaw cycles) of the mortar. Analysis of variance was employed to examine the interactions among materials. Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscopy (EDS) were also used to examine the microstructure of the mortar. Results indicate that the TS3 group with sole NT addition demonstrated stable mechanical property enhancement, achieving 28-day flexural and compressive strengths of 11.79 MPa and 38.21 MPa, respectively—representing 10.7% and 20.0% increases over the control group. The sole NC addition group exhibited significant performance fluctuations, while the TS6 group showed approximately 10% strength improvement at 28 days. Some groups experienced strength degradation due to NC agglomeration. Among the mixed-blended groups, the TS12 group exhibited the optimal “hydration-filling” synergistic effect, achieving a 28-day compressive strength of 38.89 MPa. Agglomeration occurred in most groups due to mismatched nanomaterial dosage or dispersion, resulting in strength reductions exceeding 14%. Under freeze-thaw cycles, the TS12 group demonstrated the best freeze resistance, with a compressive strength loss rate of 9.2% after 100 cycles. The TS3 group (single NT addition) and the TS6 group (single NC addition) also outperformed the control group, both suppressing freeze-thaw damage through optimized pore structure. The two-way ANOVA revealed that NT, NC, and their interaction exerted a highly significant influence on both the flexural strength and compressive strength of steel fiber cement mortar at 7-day and 28-day ages. SEM analysis revealed compact microstructures across all groups. EDS characterization results indicate that the elemental features in cement mortars with different additive combinations exhibit significant differences.

Single-side pull-out tests were conducted on crimped recycled steel fibres from waste tire wires and on Dramix 3D industrial steel fibres, both embedded in mortar and exposed for 30 and 60 days to a 7% (by mass) sodium chloride (NaCl) solution. The main objective of this research was to clearly evaluate how chloride-induced degradation influences the interfacial bond strength and mechanical performance of recycled crimped steel fibres embedded in cement mortar. Fibre tensile properties were also measured, and surface characterisation was performed via digital microscopy, Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS) and X-ray Diffraction (XRD). The results show that tire steel fibres exhibited lower corrosion resistance (mass loss 4.50% vs. 0.46% for Dramix) but a 438% roughness increase, leading to a temporary improvement in pull-out performance at 30 days (maximum load +9.94%; toughness +4.40%; average bond strength +14.56%), which declined at 60 days due to detachment of ferrihydrite and lepidocrocite layers. In Dramix fibres, goethite and magnetite formation concentrated damage in the hook region, causing pull-out reductions of −7.2% at 30 days and −9.6% at 60 days. Tensile tests revealed greater strength losses in tire fibres (−11%) than in Dramix (−5%); however, it was shown that the pull-out resistance depends more on the fibre adhesion and the surface characteristics than on its intrinsic strength.

Strengthening interfacial bonding and enhancing mechanical properties of UHPC by surface modification of steel fibers with polydopamine and nano-SiO2

Calculation models on flexural stiffness of steel fiber reinforced concrete beams with HRB600 steel bars after exposure to elevated temperatures

Ambient mass spectrometric analysis of perfluorosulfonic acids with a covalently immobilized irreversible trifluoromethyl-functionalized COF solid-phase microextraction probe.

Penetration-explosion resistance of novel steel fiber reinforced concrete-foam concrete composites reinforced by Re-entrant auxetic cellular frame

Experimental investigation on the effect of steel fibers on compressive softening behavior of reinforced ultra-high performance concrete under biaxial tension-compression

The role of steel fibers in the bond behavior of CFRP-UHPFRC joints: A mesoscale finite element study

Comparative structural behavior of full precast UHPC columns with recycled and manufactured steel fibers

Bond performance between steel rebar and steel fiber reinforced sulfoaluminate cement concrete under curing conditions of −5 °C: Experimental investigations and theoretical analysis

Impact of loading rate and elevated temperatures on the pull-out behaviour of inclined hooked-end steel fibres embedded in normal and high-strength concrete