Effect Of Steel Fiber Reinforcement Research Articles

Effect of Steel Fibre Reinforcement on Flexural Fatigue Behaviour of Notched Structural Concrete

One of the biggest challenges in facilitating the installation of concrete is the development of fibre-reinforced concrete. Although nowadays fibre reinforced concrete is relatively common, it is still necessary to deepen in the study on its behaviour, especially regarding its fatigue behaviour. This paper proposes a new methodology to analyse the bending fatigue behaviour of notched test specimens. From these tests, it was possible to verify that, despite carrying out the tests with load control, the presence of fibres extends the fatigue life of the concrete after cracking. This effect is of great importance since during the extra lifetime with the cracked concrete, the damage to the concrete will be evident and the corresponding maintenance measures can be carried out. Regarding the analysis of the results, in addition to obtaining a traditional S-N curve, two new criteria have been applied, namely energy and notch growth. From these two new approaches, it was possible to determine critical energy values that can be used as predictive indicators of the collapse of the element. Moreover, from the notch growth analysis, it was possible to determine crack growth rate as a function of the stress conditions for the concrete and the specific geometry. From the comparison among the results obtained from the different tests, a limit cracking index of 0.05 mm can be defined.

Investigating flexural performance of waste tires steel fibers-reinforced cement-treated mixtures for sustainable composite pavements

In many parts of the world, the cement-treated base course material has been extensively used within composite pavements for enhancing the load-carrying capacity of pavements. However, its vulnerability to cracking under repetitive traffic loading, due to its brittle nature, significantly cuts off its lifespan and hence reducing the sustainability of composite pavements. To provide a solution to this problem, this study is aimed to investigate the flexural performance of cement-treated base (CTB) mixtures reinforced with the Waste Steel Fibers (WSF) extracted as a residual product from the scrap tires. The flexural performance is evaluated in terms of flexural fatigue and flexural strength. Moreover, the effect of steel fiber reinforcement on the dynamic modulus of the cement-treated base mixtures was also studied. The specimens for dynamic modulus were prepared by using a gyratory compactor to better simulate the traffic loading. Furthermore, the basic split tensile strength and unconfined compressive strength of WSF reinforced CTB mixtures were also studied. Lastly, important correlations were derived based on the results obtained in this study, to predict the flexural performance of CTB mixtures in terms of dynamic modulus and fatigue life by conducting basic split tensile strength tests and flexural strength tests. Based on the results, WSF reinforcement has noticeably enhanced tensile strength, dynamic modulus, flexural strength, and fatigue life of CTB mixtures. On the other hand, the variations in the compressive strength due to WSF reinforcement were trivial. Based on the results, the steel fibers content of 0.3% by volume of the wet compacted blend has shown more promising results than lower and higher WSF contents.

Effect of Combining Fiber and Textile Reinforcement on the Flexural Behavior of UHPC Plates

A series of flexural tests were performed in order to investigate the effect of steel fiber reinforcement (SFR) in textile‐reinforced concrete (TRC) plates. Some of the specimens were reinforced only with textile, some of them only with fibers, and some of them were provided with both textile and fiber reinforcement. The concrete matrix was a self‐developed ultrahigh performance concrete (UHPC) mixture with a compression strength over 160 MPa. The tensile strength of the used textiles was around 1500 MPa for glass fiber textile and over 3000 MPa for carbon fiber textile. In case of fiber reinforcement, the concrete was reinforced with 2 vol% of 15 mm long and 0.2 mm diameter plain high strength steel fibers. The dimensions of the rectangular plate test specimens were 700 × 150 × 30 mm. The plate specimens were tested in a symmetric four‐point bending setup with a universal testing machine. The tests were monitored using a photogrammetric measurement system with digital image correlation (DIC). The paper presents and evaluates the test results, analyses the crack patterns and crack development, and compares the failure modes. The results showed a general advantageous mechanical behavior of specimens reinforced with the combination of fibers and textiles in comparison to the specimens reinforced with only fiber or textile reinforcement.

Investigation of the effect of steel fibers on the shear crack-opening and crack-slip behavior of prestressed concrete beams using digital image correlation

The effect of steel fiber reinforcement on the shear behavior of prestressed concrete beam is studied using digital image correlation (DIC) technique. Steel fiber reinforced prestressed concrete (SFRPC) beams with fiber dosages of 0.5% and 1.0% by volume were cast and tested under shear. SFRPC beams were tested under a three-point bending configuration at a shear span (a) to depth (d) ratio of 2.4 to simulate shear dominant behavior. Other parameters such as compressive strength of concrete, prestressing reinforcement ratio and level of prestressing were kept constant. The kinematics of diagonal shear cracks including crack opening and crack slip were monitored using DIC based full-field strain measurement technique. The improvement in aggregate interlock and residual tensile strength at the crack tip due to the addition of steel fiber was reflected in the post-peak response of SFRPC beams. DIC analysis revealed that the full depth crack was formed in all the SFRPC beams before reaching their peak loads. The dilatant behavior was found to be consistent for all the test specimens (control and fiber reinforced concrete beams) up to peak load. The test results portray that the addition of steel fibers stiffens the post-peak response and reduces the crack opening and crack slip. Moreover, the failure mode changed from shear (brittle) to flexure-shear (less brittle) mode.

Effect of Steel Fibre Reinforcement on Early Strength of Concrete

Effect of Steel Fibre Reinforcement on Early Strength of Concrete

Structural performance of steel fibre reinforced concrete — Part I. Overview of the experimental program

Abstract The papers of the series deal with experimental characterisation of mechanical as well as structural properties of different steel fibre reinforced concretes that can be used for several structural applications. An extensive experimental programme (six years) has been developed to investigate the effect of steel fibre reinforcement on the mechanical performance and structural behaviour of concrete specimens. Specimens and test methods were selected to be able to detect realistic behaviour of the material, representing clear effect on the structural performance. Material compositions, test methods, type of test specimens will be detailed in the presented paper (Part I). Furthermore, compressive strength (Part II), stress-strain relationship (Part II), splitting strength (Part III) and toughness (Part IV) will also be discussed. In the light of the motivation to determine the structural performances of 1D concrete structural element affected by steel fibre reinforcement, bending and shear behaviour (Part V) as well as serviceability state (Part VI) of steel fibre reinforced concrete beams will be analysed. Since normal force — prestressing force — can affectively be used to improve the structural performances of RC element flexural tests were carried out on prestressed pretensioned steel fibre reinforced concrete beams (Part VII). Moreover, focusing on the in-plane state of stresses for 2D structures, behaviour of steel fibre reinforced concrete deep beams in shear and steel fibre reinforced concrete slabs (Part VIII) in bending will be explained. Finally, based on the wide range of the experimental and analytical studies on the presented field, a new material model for the 1D uniaxial behaviour (Part IX) and its possible extension to the 3D case (Part X) will be described hereafter. All papers will put emphasis on the short literature review of the last four decades.

Flexural and shear behavior of steel fiber reinforced SCC beams

This paper deals with the effect of steel fiber reinforcement on the behavior of Self-Compacting Concrete (SCC) beams. Bending tests were carried out to examine the effect of low fiber content (0.25% by volume) on the flexural behavior of beams with different amounts of steel rebar reinforcement. The study compares the behavior of reinforced concrete beams cast either with control SCC and the one of Fiber-Reinforced Self-Compacting Concrete (FRSCC). Fibers used were made of stainless amorphous metal. Their influence was studied through the global and local mechanical responses of the beams. The results show that fiber reinforcement allows the control of cracking to be improved. Yielding, ductility and load bearing capacity are not modified by the fiber reinforcement; its effects are limited to the kinetics and distribution of cracks. If it was observed that the used fiber content reduced stresses in the stirrups, they could not be considered as a solution to replace stirrups. However, their ability to transfer tensile stress through a crack provided greater beam stiffness, notably with a low steel bar reinforcement ratio. It was concluded that stainless steel fiber reinforcement is a suitable solution to control crack width in reinforced concrete elements in aggressive environments with respect to the limitations imposed by design codes such as the European code Eurocode 2.

Restrained shrinkage cracking in steel fibre reinforced and rubberised cement-based mortars

The paper focuses on the combined effect of Steel Fibre Reinforcement and of Rubber aggregates on the resistance to restrained shrinkage cracking of cement-based mortars. The kinetics of restrained shrinkage cracking of a control mortar is compared both to the one incorporating a single fibre content as reinforcement and to the above fibre reinforcement combined to rubber aggregates substitution. Two rates of substitution were considered in the case of Steel Fibre Reinforced and Rubberized Mortar (SFRRM). The used rubber aggregates are obtained by grinding used tyres, a way that may address the demand for the conservation of a clean environment by recycling an industrial by-product. Fibre-reinforced mortar was based on the control mortar and one metal fibre content was studied: 40 kg/m3 (0.5% by volume). The used fibres have a high bond with the cementitious matrix. SFRRM composites were cast using two contents of rubber aggregates: 20 and 30% by volume replacing mineral aggregates and the one fibre content reported here above (40 kg/m3). Tests were conducted using ring type specimens to simulate restrained shrinkage cracking according to ASTM C 1581-04 standard. Additionally, after the cracking occurred, the development of the crack widths was measured by video-microscope. Ring tests demonstrated that the SFRRM exhibit high strain capacity prior to macro-cracking localization and the effectiveness of rubber aggregates along with their positive synergistic effect when combined with fibre reinforcement to improve resistance to shrinkage cracking. It is a promising solution to improve the durability of large surface area such as pavements and thin bonded cement-based overlays, whose durability is often limited by shrinkage cracking.

Young’s modulus of fiber-reinforced and polymer-modified lightweight concrete composites

In this paper, the effect of steel fiber reinforcement and polymer modification on the Young’s modulus of lightweight concrete aggregates is investigated. Through experimental measurements, composite property models that best describe the mixtures in terms of the properties and volume fractions of their constituents are identified. The relationship between various composite properties and the mixtures used to produce the lightweight concrete are also explored qualitatively.

Behavior of high strength concrete with and without steel fiber reinforcement in triaxial compression

Based on an extensive experimental program, this paper studies the behavior of high strength concrete and steel fiber reinforced high strength concrete under uniaxial and triaxial compression. Triaxial stress–strain relations and failure criteria are used to evaluate the effect of steel fiber reinforcement on the mechanical properties of high strength concrete in triaxial compression, which is found to be insignificant.

Effect of Fiber Reinforcement on Bond Strength of Tension Lap Splices in High-Strength Concrete

This research evaluates the effect of steel fiber reinforcement on the bond strength and ductility of the mode of bond failure of tension lap splices anchored in high-strength concrete (HSC) test specimens. 12 full-scale HSC beam specimens were tested. Each beam was designed with bars spliced in a constant moment region at midspan. Test results indicated that the use of steel fibers in the splice region increased the bond strength and the ductility of the mode of failure of the beam specimens.

Toughness measurements on steel fibre-reinforced high strength concrete

The paper reports on strength and toughness measurements on a range of normal and high strength concrete mixes, with and without steel fibre reinforcement. Cube strength, modulus of rupture, cylinder splitting and torsional-tension test results are reported together with toughness measurements determined via two fracture-type test specimens (standard RILEM three-point notched beams in flexure and eccentrically loaded notched cubes). In the toughness tests, crack mouth opening displacement (CMOD) was measured and used in a closed loop testing mode to achieve complete load/displacement curves. Good correlation was observed in the strength tests and the two toughness tests showed similar load-CMOD curves and toughness indices. However, traditional toughness indices are unsatisfactory with load-CMOD tests, and further work is necessary to define acceptable toughness measurements, which may also have to account for size effects. The effect of steel fibre reinforcement on high strength (up to 120 N mm 2 ) and normal strength concrete is similar.

Effect of Steel Fiber Reinforcement on Fresh Mix Properties of Concrete

Effect of Steel Fiber Reinforcement on Fresh Mix Properties of Concrete

Influence of steel fibre reinforcement on the fracture behaviour of concrete in compression

Experimental results are presented to describe the compressive load-deformation characteristics of steel fibre reinforced concrete. The influence of steel fibre reinforcement on the fracture process of concrete is discussed, based on data for various volumes of melt extract, hooked, straight and crimped steel fibres. The results indicate that the primary effect of steel fibre reinforcement on the fracture behaviour of concrete up to ultimate stress is very similar to the characteristics imparted by coarse aggregate inclusions. The initiation and critical stress and strain values decrease with increasing fibre content and the volume of the crack phase in the matrix increases. Steel fibre reinforcement improves the energy absorption capacity of concrete due to the higher lateral strain capacity imparted by steel fibres and due to energy dissipation during pull-out of fibres which bridge tension and shear cracks in the failing matrix.