High-strength Fiber-reinforced Concrete Research Articles

Analysis of Tensile Specific Deformation of Fiber Reinforced Concrete Beams via FEM

The use of fiber reinforced concrete (FRC) for structural purposes has been gradually increasing and this growth has resulted in the emergence of several standards. With regard to Brazil, the first standard related to the design of FRC structures was published in 2021. In this standard, the calculation aspects for sizing FRC structural elements are represented, however, the behavior of specific tensile deformations is not fully illustrated. Based on this, a study is presented regarding the determination of the tensile specific deformation at the beginning of the plastic boundary (ε_Fp) of beams fiber reinforced concrete (FRC) and beams fiber reinforced high strength concrete (FRHSC). To establish these deformations, we used works found in the literature and through numerical analysis via the finite element method (FEM), and through the mesh convergence analysis of the finite elements obtained from the ABAQUS software, the beams were analyzed. According to the study carried out, it was found that, for FRC beams and FRHSC beams, ε_Fp corresponded to a value in the order of 5.0‰ and 6.5‰, respectively. This illustrates the possibility of greater deformation occurring at the beginning of the plastic boundary for the FRHSC and shows the potential of the work to contribute to the establishment of guidelines for the structural aspects of the FRC.

Shear behaviour of deep beams strengthened with high-strength fiber reinforced concrete jackets

The study addresses the pressing need for effective strengthening of reinforced concrete (RC) members, specifically focusing on shear-critical deep beams. One of the most effective methods for strengthening RC members is the fiber reinforced concrete (FRC) jackets. However, limited number of studies have been conducted on deep beams strengthened with FRC. To address this gap, this paper presents an experimental investigation for strengthening of shear-critical deep beams using high-strength fiber reinforced concrete (HFRC) jackets. The experimental program involves testing three large-scale deep beams, including a reference specimen and two strengthened beams with thin HFRC jackets of different thicknesses (34 mm and 26 mm). The HFRC jackets featured straight steel fibers with a volumetric ratio of 1.13 %. According to the experimental results and analysis, it is found that an HFRC jacket of 34 mm thickness upgraded the strength by around 25 % and enhanced the crack control by reducing crack widths by around 50 % at the same absolute load with respect to the reference specimen. From the measured deformed shapes of the compression zone of the specimens, it is concluded that the main principles of the two-parameter kinematic theory of deep beams remain valid for HFRC-strengthened members, and these principles can be used to establish a complete modelling approach for such members.

Behavior of Reinforced Concrete Circular Columns Subjected to Double Curvature Buckling Moment

This paper investigates experimentally and numerically structural performance of reinforced concrete (RC) circular column under double curvature buckling moment. RC circular columns are popularity embraced in RC structures not only owing to its esthetic, attractive appearance and easy for construction, but also for its better contribution for stress resistance. However, the corner or edge columns may be exposed to edge moment (EM) transferred from beam–column joint with double curvature effect. The current investigation proposes to understand the structural exhibition of such columns subjected to double curvature buckling edge moment generated at beam–column joint considering some parameters. A total number of 11 full-scale RC circular columns were constructed, installed, and then tested up to failure studying four parameters. These parameters were: clear height-to-diameter ratio (λ), longitudinal and lateral steel ratios (μ and ρ, respectively) and concrete type. The λ ratio has been introduced with: 4.89, 4.51 and 4.14. The μ ratio has been presented by: 2.2%, 2.3%, 2.6%, and 3.1%, while the ρ ratio was employed with: 0.84%, 0.93%, 1.00% and 1.18%. Three concrete types were studied; one of them was normal concrete (NC), while the other ones were high-performance concretes (HPCs) which were engineered cementitious composite (ECC) and high-strength fiber reinforced concrete (HSFRC). Experimental outcomes revealed that all studied parameters could affect and upgrade the structural performance; however, both longitudinal reinforcement and height-to-diameter ratio provided significant enhancement (about 51%–64%). Parallel to those exploited experimentally, nonlinear three-dimensional finite element models (FEMs) were installed, executed and established considering experimental outcomes producing an acceptable model with an under/over-estimation of about 4%.

Mechanical properties and dynamic compression behaviour of basalt/polypropylene fibre-reinforced high-strength concrete

Concrete is a typical brittle material. Although it has excellent compressive performance, it can be damaged by dynamic loads such as explosions and impacts due to its poor tensile strength and cracking susceptibility. In an attempt to improve the impact resistance of concrete, a ∅100 × 50 split Hopkinson pressure bar was used to carry out impact tests on high-strength concrete (HSC) specimens with different volume contents (0.1%, 0.3% and 0.5%) of basalt fibre (BF) or polypropylene fibre (PPF) under three different impact pressures. The compressive strength, splitting tensile strength, flexural strength and dynamic compression performance of BF/PPF-reinforced HSC (C60) were studied. With an increase in impact pressure, increasing the volume content of fibre significantly improved the impact resistance of the concrete, due to the crack resistance and bridging effects of the fibre. The BF and PPF were found to be sensitive to the strain rate. Within a certain range of strain rate, the relationship between peak stress and strain rate was positively correlated. Dynamic stress–strain curves of concretes with optimal dosages of BF and PPF were obtained through dynamic compression tests.

Performance of corroded RC beam–column joints repaired using a hybrid scheme with HSFRC and stirrups replacement

AbstractThe present study proposes a new technique for retrofitting corroded beam–column joints (BCJs) using high‐strength fiber reinforced concrete (HSFRC) and stirrups replacement. The entire corrosion‐affected concrete was removed and replaced with HSFRC. The corroded reinforcing bars were cleaned and treated to resist the progression of the corrosion mechanism. The severely pitted stirrups were replaced with new stirrups. Four exterior BCJ specimens were tested under seismic loading to determine the effectiveness of the proposed retrofitting scheme. The efficacy of the proposed retrofitting scheme is determined in terms of the hysteresis response, stiffness degradation, cumulative energy dissipation, ductility, and damage index. A significant delay in the fracture of severely pitted reinforcing bars was experienced for the corrosion‐damaged retrofitted specimens compared to the corroded unretrofitted specimen. The cumulative energy dissipation of the corroded unretrofitted and corroded retrofitted specimens was 0.4 and 1.3 times that of the reference specimen, respectively, indicating the effectiveness of the retrofitting strategy, as both specimens had similar corrosion rates. The test results indicated that the proposed retrofitting technique effectively improved the seismic performance of the corrosion‐damaged BCJs.

Investigation on the flexural behavior of high‐strength fiber‐reinforced concrete

AbstractThe present research investigated the flexural behavior of high‐strength fiber‐reinforced concrete (HSFRC) with six different types of fiber: hooked‐end and crimped steel fibers, chopped and pultruded glass fibers; monofilament and twisted polymeric fibers. An extensive experimental program with 108 specimens for 3‐point bending tests was carried out and the parameters analyzed were the fiber content (0.50%, 0.75% and 1.00% in volume), the fiber type and the compressive strength of the concrete (60 and 90 MPa). Statistical analyses were performed and showed that regardless of the fiber material, increasing the amount of fibers added to concrete increases residual strength and toughness. Limit of proportionality is not affected by the addition of fibers, while postcracking behavior, on the other hand, is controlled by the fibers. Increasing the compressive strength of the concrete matrix affect mainly the limit proportionality of all mixes and the postcracking behavior of the concrete reinforced with hooked‐end steel fibers. The classification of HSFRC and the conditions required for HSFRC for use in structural applications according to the fib Model Code 2010 were also discussed, and it was verified that such conditions are not consistent with the experimental results and should be revised for high‐strength fiber‐reinforced concrete.

High-strength fiber-reinforced concrete: assessing the impact of polyvinyl alcohol, glass, and polypropylene fibers on structural integrity and cost efficiency

This study delves into the realm of high-strength fibre reinforced concrete (HSFRC), a pivotal material in contemporary construction, with a focus on elucidating its mechanical robustness and durability enhancements facilitated by fibre reinforcement. Previous research on HSFRC has provided mixed results and often neglected the cost implications. However, this study incorporates an array of fibres, encompassing steel, polypropylene, and polyvinyl alcohol, in varied proportions as well as their cost implications to provide a comprehensive evaluation of their impact. Through standardized tests such as compression strength, splitting-tensile strength, flexure strength, water permeability, and ultrasonic pulse velocity tests, alongside an exhaustive cost–benefit analysis, the study uncovers the substantial influence of fiber type and proportion on HSFRC 's properties. Noteworthy findings indicate that both fiber type and fiber ratio can change the strength and durability properties of concrete considerably, however, the use of 1.5% glass fiber gives the best results, in improving the properties of HSC. Moreover, despite the initial higher costs associated with HSFRC production, its protracted durability and diminished maintenance requisites yield substantial long-term economic advantages. Consequently, it is inferred that judicious selection of fiber types and proportions plays a pivotal role in maximizing the performance and cost-effectiveness of HSFRC, thereby advocating for its broader integration within the construction sector. Subsequent research endeavours should concentrate on fine tuning fiber content and types to further elevate HSFRC 's properties.

An Experimental Study on the Influence of Different Cooling Methods on the Mechanical Properties of PVA Fiber-Reinforced High-Strength Concrete after High-Temperature Action.

High-strength concrete (HSC) has a high compressive strength, high density, excellent durability, and seepage resistance, but its deformation ability is weak. Adding fibers can improve the physical and mechanical properties of HSC. Additionally, the HSC structure may face the threat of fire. In the process of fire extinguishing, the damage mechanism of high-temperature-resistant concrete is complicated due to the different contact conditions with water at different locations. Hence, it is essential to conduct pertinent research on the behavior of fiber-reinforced HSC with different cooling methods after high-temperature action. In this paper, polyvinyl alcohol fiber (PVA fiber) was selected to be added into the HSC to carry out high-temperature experimental research, so as to explore the apparent changes, failure pattern, and mass loss rate of the fiber-reinforced HSC using different cooling methods and analyze the influence of its residual compressive strength and flexural strength. The test results suggest that, with the increase in heating temperature, the color of the specimen's surface transitions from dark blue-gray to white, and the quantity of surface cracks on the specimen gradually rises. The mechanical strength gradually decreases as the heating temperature increases. At a consistent heating temperature, the mechanical strength initially rises, and then falls with an increase in fiber content. The maximum compressive strength and flexural strength were achieved at PVA fiber contents of 0.2% and 0.3%, respectively. For different temperatures and fiber contents, the mechanical strength after natural cooling is generally higher than that after immersion cooling. In addition, X-ray polycrystalline diffractometry (XRD) and scanning electron microscopy (SEM) tests were conducted to analyze the compositional alterations and microstructure of the fiber-reinforced HSC following high-temperature exposure, accompanied by an explanation of the factors influencing the alterations in the physical and mechanical properties. Therefore, the findings of this study can serve as a valuable reference for the utilization of HSC in engineering structures and contribute to the advancement of HSC technology.

Mechanical Properties and Microstructure of Cellulose Fiber- and Synthetic Fiber-Reinforced High-Strength Concrete

Mechanical Properties and Microstructure of Cellulose Fiber- and Synthetic Fiber-Reinforced High-Strength Concrete

Influence of Drying Conditions on the Durability of Concrete Subjected to the Combined Action of Chemical Attack and Freeze-Thaw Cycles.

The durability of concrete is critical for the service life of concrete structures, and it is influenced by various factors. This paper investigates the impact of the relative humidity (RH) of the curing environment on the durability of five different concrete types. The aim is to determine a suitable approach for designing concrete that is well-suited for use in the salt lake region of Inner Mongolia. The concrete types comprise ordinary Portland cement (OPC), high-strength expansive concrete (HSEC), high-strength expansive concrete incorporating silica fume, fly ash, and blast furnace slag (HSEC-SFB), steel fiber-reinforced high-strength expansive concrete (SFRHSEC), and high elastic modulus polyethylene fiber-reinforced high-strength expansive concrete (HFRHSEC). All these concrete types underwent a 180-day curing process at three distinct relative humidities (RH = 30%, 50%, and 95%) before being subjected to freeze-thaw cycles in the Inner Mongolia salt lake brine. The curing environment with a 95% RH is referred to as the standard condition. The experimental results reveal that the durability of OPC and HSEC decreases significantly with increasing relative humidity. In comparison with the control sample cured in 95% RH, the maximum freeze-thaw cycles for concrete cured in lower RHs are only 31% to 76% for OPC and 66% to 77% for HSEC. However, the sensitivity of the durability of HSEC-SFB, SFRHSEC, and HFRHSEC to variations in RH in the curing environment diminishes. In comparison with the corresponding reference value, the maximum freeze-thaw cycles for samples cured in dry conditions increase by 14% to 17% for HSEC-SFB and 21% for SFRHSEC. Specifically, the service life of HFRHSEC cured in a low RH is 25% to 46% higher than the reference value. The durability of HSEC-SFB, SFRHSEC, and HFRHSEC has been proven to be appropriate for structures located in the salt lake region of Inner Mongolia.

Experimental study on the fully encased composite short columns made with high-strength fibre-reinforced concrete

Experimental study on the fully encased composite short columns made with high-strength fibre-reinforced concrete

Abrasion and Maintenance of High-Strength Fiber-Reinforced Pervious Concrete

This study examines the properties of ordinary and high-strength fiber-reinforced pervious concrete, aiming for a 28-day compressive strength exceeding 40 MPa with a target porosity close to 15%. Utilizing glass fiber (at 0.25% and 0.5% volume ratios) and steel fiber (at 1% and 2%), the study conducts mechanical and abrasion resistance testing on pervious concrete specimens. Sand dust clogging experimental simulations assess permeability coefficients for both application and maintenance purposes, revealing optimized maintenance, including vacuum cleaning and high-pressure washing, can restore water permeability to over 60%. The specific mix designs demonstrate high-strength pervious concrete achieves a 28-day compressive strength ranging from 40 to 52 MPa, with corresponding porosities ranging from 7% to 16%. Results highlight the significant impact of the ASTM C1747 impact abrasion test, where ordinary pervious concrete exhibits a cumulative impact abrasion rate reaching 60%, contrasting with approximately 20% for other high-strength specimens.

Sustainable design framework for enhancing shear capacity in beams using recycled steel fiber-reinforced high-strength concrete

According to a recent estimate, over 1.5 billion wasted tyres which containing over 40% of vulcanised rubber and 15% of steel fibre are discarded yearly, which posing a serious threat to circular economy implementation and transition to net zero. To minimise the greenhouse gas(GHG) emission and the environmental side effect caused by burning and burying these waste tyres, recycling and reusing these materials for sustainable structural designs has become the centre of attention. This paper focuses on applying recycled bead steel fibre to improve the shear capacity of fibre-reinforced concrete beams. Moreover, the existing national standard known as Eurocode 2 and TR63 can hardly illustrate the relationship between fibre and high-strength concrete. This study is the first to investigate shear behaviours of high-strength industrial and recycled steel fibre reinforced concrete beams with consideration of different shear span ratios. Therefore, twenty real-scale beams are constructed to examine the shear capacity of high-strength industrial and recycled steel-fibre reinforced concrete beams, which aims to compare the improvement of shear strength through experiments and identify different shear strength improvements of the two categories of steel fibre. Besides, comprehensive data of 164 beams from previous studies have been collected to benchmark with the experimental results for the formula design. This study proves the feasibility of replacing industrial steel with recycled steel fibre to improve the shear capacity of fibre-reintroduced concrete beams. Moreover, there are six novel equations designed developed using Eurocode 2 and TR63 as a basis in this study. Based on the findings of the paper, the proposed formulas demonstrate remarkable accuracy, with an average value of 0.982 and standard deviation of 0.213, respectively. Following an exhaustive comparison of RSF and ISF reinforced concrete beams, with a focus on economic expenditure and GHG emissions, it can be concluded that RSF offers superior economic and environmental benefits, which reduce the emissions up to 25.39% and price up to 28.04% when replacing ISF 0.8% RSF, respectively.

Experimental investigation on fresh and hardened properties of high strength fibre reinforced concrete using GGBFS and micro silica

The use of High Strength Concrete (HSC) has increased now a days. The concrete is one of the most useful construction materials, but the major defects of concretes are brittle in nature, low workability and low tensile strength. Experimental study is carried out to assess fresh and hardened properties of high strength fibre reinforced concrete (HSFRC) of grade M70. In addition to normal materials, silica fume and GGBS are added to achieve higher strength and poly propylene fibres are added to improve its ductility. The content of silica fume and GGBS is 5% and 25% respectively by weight of cement. Water to cementitious material ratio is 0.31. Mixes with different percentages of poly propylene fibres such as 0.5%, 0.1%, and 1.5% by the weight of cementitious content are denoted as HSFRC 1, HSFRC 2, and HSFRC 3, respectively. To improve the workability characteristics of the low water-binder ratio HSC mix, the Poly Carboxylate Ethylene-based chemical admixtures are used. The fresh properties were investigated in terms of slump flow and mechanical performances of the HSFRC over HSC are evaluated in terms of compressive, flexural, split tensile strength.

Bond durability performance of sand-coated BFRP bars in high-strength fiber reinforced concrete

The ever-increasing utilization of fiber-reinforced polymer (FRP) bars has led to a surge in research regarding their bonding properties with concrete. In this study, the bond durability behavior between high-strength fiber-reinforced concrete (FRC) and sand-coated basalt FRP (BFRP) bars was examined under three different environmental conditions including immersion in seawater solution at 50 °C for 3, 6, and 9 months, immersion in the sulfuric acid solution for 3, 6, and 9 months with an ambient temperature range of 20 to 30 °C, and exposure to 270 freeze–thaw cycles. A total of 60 pull-out samples were prepared using either basalt (B) fibers or polypropylene (PP) fibers. Plain concrete pull-out samples were served as controls. Test results revealed that all exposures have degraded the bond, leading to pull-out failure in all of the specimens. Exposure to 50 °C seawater was found to cause the most significant degradation. However, the use of basalt fibers helped to mitigate the loss of bond strength in the specimens when compared to plain concrete specimens. For example, after 3, 6, and 9 months of exposure to 50 °C seawater, bond strength retentions of 73.58%, 56.04%, and 34.47% were observed for basalt FRC (BFRC) specimens, compared to 39.64%, 49.37%, and 29.61% for plain concrete specimens. On the other hand, a lower retention in bond strength of 16.28% was recorded for polypropylene FRC (PPFRC) specimens at 9 months of exposure to 50 °C seawater. The bond stress-slip relationship of the tested bars was accurately predicted using two calibrated analytical models: the Eligehausen, Popov, and Bertero (BPE) model and the Cosenza, Manfredi, and Realfonzo (CMR) model. Notably, both models showed a strong correlation with the observed bond stress-slip relationships in the experiments.

Seismic performance of corroded non-seismically and seismically detailed RC beam-column joints rehabilitated with High Strength Fiber Reinforced Concrete

The experimental investigation was undertaken to restore the seismic performance of the corrosion-damaged beam-column joint (BCJ) rehabilitated with High Strength Fiber Reinforced Concrete (HSFRC). A total of eight exterior beam-column sub-assemblages were cast following two types of reinforcement detailing as per IS 456:2000 and IS 13920:2016, respectively. Three specimens from each reinforcement detailing regime were subjected to three different levels of corrosion and thereafter rehabilitated with HSFRC. The hysteresis behavior, energy dissipation, stiffness degradation, crack patterns, and damage index of all rehabilitated specimens are analyzed and compared with the conventional specimens. Test results indicate that the replacement of damaged concrete with HSFRC can recover the strength of corrosion-damaged BCJ when the corrosion ratio is within 10 %. The peak load-carrying capacity and initial stiffness of rehabilitated specimens showed a significant increase up to 36 % and 84 % respectively, when compared to control specimens. The ductile detailing rehabilitated specimens showed up to 90 % higher equivalent viscous damping ratio than the non-ductile ones, exhibiting close stirrups arrangement superiority. Despite recovering the load-carrying capacity at initial drifts, the seismic performance of non-ductile and ductile rehabilitated specimens having 17.76 % and 20.32 % corrosion ratio were not recovered at higher drifts.

Shear behaviours of steel-HSFRC welded stud and perfobond rib connectors under static push-out experiments

In this study, high-strength fibre-reinforced concrete (HSFRC) was introduced into steel–concrete composite girders owing to its high strength, good cracking, and impact resistance. Sixteen push-out specimens were tested to study the shear behaviours of the welded stud and perfobond rib connectors used in steel-HSFRC composite girders. The failure modes, load–slip curves, and shear behaviours of the push-out specimens were analysed and compared. The experimental results indicate that the shear capacity and stiffness of these two types of connectors are improved when they are used in steel-HSFRC composite girders, whereas the ductility of the welded stud and one-hole perfobond rib connectors decreases. The stud diameter has a significant effect on the shear behaviour of welded studs, unlike the stud length. The shear capacity of perfobond rib connectors increases with an increase in the perforating rebar diameter and hole number. The initial stiffness and ductility of perfobond rib connectors were larger than those of welded stud connectors with similar shear capacities. Finally, shear capacity prediction equations for welded studs and perfobond rib connectors embedded in HSFRC are proposed and verified to have good accuracy and applicability.

Behavior of reinforced concrete ring beams strengthened with sustainable materials

Reinforced Concrete Ring Beams (RCRBs) have been used in Reinforced Concrete (RC) buildings, tanks, and roof shell structures, such as domes and cones. The curviness feature of RCRBs may result in excessive tensile stresses that may consequently generate critical cracks in concrete, particularly when the beams are constructed with Normal Concrete (NC). This paper presents experimental and numerical investigations on the structural behavior of RCRBs strengthened with sustainable materials. The experimental results on 12 RCRBs constructed with various types of concrete and strengthened with several techniques are presented and discussed. The specimens were made of NC, Engineered Cementitious Composite (ECC), High Strength Concrete (HSC), and High Strength Fiber Reinforced Concrete (HSFRC). Three strengthening techniques were employed for strengthening, including the External Bonded Reinforcement (EBR) with stainless-steel plates (SSPs), the Near Surface Mounted (NSM) with steel bars, and the pre-stressing system. Three-dimensional Finite Element Models (FEMs) were developed by using ABAQUS software to simulate the nonlinear performance of RCRBs. The test results show that the use of sustainable materials in RCRBs can remarkably improve the strength and ductility of RCRBs. In addition, the strengthening techniques are effective in enhancing the responses of RCRBs against the applied loads. Moreover, the thickness and configuration of SSPs significantly affect the ultimate and energy absorption capacities of RCRBs. Finally, a good agreement is observed between numerical predictions and experimental results, suggesting that the finite element model can be employed for further investigations.

Response of high-strength concrete beams with corrugated discrete steel fibers to small shear span-depth ratios

The behavior of high-strength, fiber-reinforced concrete (HSFRC) beams under concentrated loads was affected by many different aspects, such as the type of fibers used and the volume percent of the fibers; nevertheless, the behavior was primarily affected by modifying the shear span-to-depth ratio (a/d). In this experimental investigation, the influence of a/d ratios (ranging from 1.5 to 2.2) is investigated on the response of twelve high-strength fiber-reinforced concrete (HSFRC) beams containing varying amounts of discontinuous steel fiber (vf) in the concrete mixture. The purpose of this study was to analyze the manner of failures of the tested beams and to identify a limiting a/d for effective beam depth. Shear failure was observed in high-strength concrete (HSRC) beams with a vf of 0% at a/d ratios as high as 2.2, according to the findings of the study. Altering either the a/d ratios or the vf had an effect on the way in which the HSFRC beams responded to the stimulus. Some of the HSFRC beams that were put through the shear–flexure test failed. In addition, the findings demonstrated that, as the a/d ratio increased up to 2.2, the beams with a vf of 0.5% and 0.75% broke in pure flexure with multi-cracking. This indicates that the a/d ratio has a substantial impact on the various failure behaviors of HSFRC beams.

High strength fiber reinforced concrete with steel slag as partial replacement of coarse aggregate: Overview on mechanical and microstructure analysis

The growth in construction development and an increase in the number of predisposed waste products has instigated vendors and investigators in studying the use of substitute resources that valor preserve usual resources and defend ecology, helping the reduction of aggregate occupying 70% volume in concrete. Steel slag, a byproduct of steel industry can be used to substitute aggregates in standard concrete mixtures. Steel slag has essentially identical properties to ordinary aggregates and is easily obtained as a byproduct of the steel industry. Steel slag usage conserves natural resources and cleans the environment. This work primarily intends to study the mechanical behaviour of high strength fiber reinforced concrete (HSFRC) of M70 grade such in compression and tension tests, by replacing coarse aggregate by 40 %, 45 % and 50% with steel slag and pondering 1 % of steel fibers. The microstructure of concrete mixes is analysed, results indicated that 50% replacement has better performance in the strength and microstructural aspects.