Steel Fiber Concrete Research Articles

Research status and prospect of waste steel fiber reinforced concrete

Scrap steel fiber concrete (SFRC) is a new kind of concrete material, which uses the scrap steel fiber from the scrap tire as the reinforced fiber of FRP bar fiber reinforced concrete, replacing or partially replacing the traditional steel fiber and synthetic fiber. This paper summarizes the research status of waste steel fiber at home and abroad, including the mechanical properties of compressive and tensile resistance, the mixing amount and use requirements of waste steel fiber, and finally the development prospect of waste steel fiber concrete is forecasted

Recycled materials execution through digital image processing

The main aim of composition is to investigate reinforced concrete using a novel approach to the digital image process (DIP). Utilization of the photogrammetry principles to track features and assign their position to a predetermined coordinate system. The present study deals with the systematic investigation of the cracks propagate and created inside the factual is a crucial feature of the sharp Ordinal pictures. They are apprehended ahead of overwhelming (undistorted position) and specific cases of loading. The pictures were explored through the connexion procedure to reckon the shallow displacements, strains, flaw overture, descending shortcomings, transposition of point load, flaw interval, and break gradient position. The obtained results of concrete material using Matlab® tool. The behavior of various samples such as conventional mix, 3%, 3.6%, and 4.2% steel fiber concrete was examined using DIP. The considered of augment structural health monitoring techniques currently practice in various applications. DIP technique employed to assess the external displacement and damage within concrete. In general, various faults transpire in hardened concrete specimens. This analysis deal with damage estimation inside reinforced concrete examples concurred with the code IS:456(limit states approach) through novel techniques. The connexion scrutiny using the program illustrates the proportional displacement along with the rupture arrest on the glued boundaries and the frictional interface. The attained displacement quantities are converted to strain using this novel technique, and respected stresses were obtained. This analysis is a primary pace about expending the digital image process technique in incorporation with high-speed taking pictures to capture the highly transitory singularities complexed in deep cracks.

Savijanje AB greda od običnog betona i betona s čeličnim vlaknima armiranih različitim vrstama FRP šipki

Fibre Reinforced Polymer (FRP) bars can be used as an alternate for reinforcing bars to avoid corrosion of steel. Samples of reinforced concrete beams cast with normal or steel fibre concrete (SFC), internally reinforced with Glass Fibre Reinforced Polymer (GFRP) or steel bars, are prepared and tested in this paper. Experimental results show that compressive strength of concrete increases with an increase in steel fibre (SF) ratio used in this study (from 0% to 1.5%). Also, the beams reinforced with GFRP bars have a lower initial stiffness and higher ductility than those reinforced with steel bars.

Study on cast set up concrete steel fibers in various construction fields

Abstract The major significant technologies that is growing rapidly since 1980 in concrete technology is SCC (self-compacting concrete). It is initially developed in japan, and further extended all over the entire world with constant enhancing and divergent amount of applications. Because of its definite increased properties, the term SCC might research over the concrete structures quality and open novel fields for concrete implementation. This SCC gets dense and compacted because of their own weight. The simulation study is conducted to examine divergent characters such as workability & strength of SCC. Moreover, a test comprising several proportions of fiber for specific combination of SCC has been conducted. Here, the test models utilized for researching the new concrete properties were L-Box, V-Funnel, Slump test and U-Tube. Some of the properties like tensile, flexure and compressive strength of the technology SCC have also been examined. The test comes exhibited that the SCC workability characteristics are within boundaries of SCC limits. The difference of divergent factors of M50 (hardened concrete) in regard to several percentages of contents of steel fibre have also been investigated.

Failure Mechanism of Diamond Saw Blade Sawing Concrete

Sawing concrete with diamond saw blade is a complex process with alternating loading. However, due to the poor working conditions of the thin circular blade made of high manganese steel core, and the lack of research on its failure mechanism, a large number of used blade are abandoned every year in China and all over the world without steel core reused. Therefore, exploring the failure mechanism of diamond saw blade can improve the cutting quality and efficiency, and extend the service life of the saw blade. In this paper, the failure mechanism of diamond saw blade sawing concrete was analyzed through segment wear experiment and microstructure observation of segments and steel core of failed sawblade. The results showed that the stress concentration exited at the bottom of slot, where it became the most dangerous section. The crack at the bottom of the cooling hole caused the saw blade to deviate violently and bear unevenly. The microstructure is great different along the outer to the center of the steel core. The closer to the teeth of the saw blade, the more obvious the microstructure change, while the central core still retains the original structure. Under the same sawing area of 0.01m2, the stable dust adhesion of plain concrete is less than that of the steel fiber concrete. However, when the dust adhesion increases to more than the stable adhesion, the phenomenon of blockage will occur. Therefore, deflection, crack, wear and burn were the main failure reasons of diamond saw blade when sawing concrete.

Quality improvement of monolithic steel fiber concrete floor slabs with void formers

The features of the technology for the monolithic floors construction using void formers have been studied, its disadvantages have been identified and the ways to eliminate them have been proposed. At the first stage of this work, the reasons for the low quality of monolithic floors with void formers were studied by the method of visual and measuring control, and by comparing with known scientific and industrial data. At the second stage, by the method of systematization the main defects and damages arising in the construction, repair and usage of these floor slabs were classified and ways to eliminate them were proposed. At the third stage, the features of the quality control system, carried out directly during the construction of monolithic floor slabs using void formers, were studied, the composition of operations and control tools were proposed. According to the research results, it was found that the use of steel-fiber concrete in floors with non-removable void formers allows to reduce the percentage of reinforcement by 9.82%, compared to other known options, and also to reduce the consumption of concrete in comparison with a solid monolithic slab almost by half. The proposed quality control system will improve the efficiency of monolithic floor slabs using void formers.

Performance Test of C60 Self-Compacting Steel Fiber Concrete

Self-compacting steel fiber concrete must meet the strength standard after steel fiber is added and must have good fluidity. The test results show that the addition of steel fiber to concrete will affect the fluidity of concrete. Compared with ordinary concrete, the addition of steel fiber will improve the compressive strength and flexural tensile strength of concrete to varying degrees. The mix proportion test can be carried out in stages, i.e. the mix proportion meeting all performance indexes used is determined first, then steel fiber is added and adjusted to determine the best mix proportion.

КРУЧЕНИЕ С ИЗГИБОМ СТАЛЕФИБРОЖЕЛЕЗОБЕТОННОЙ БАЛКИ ПРЯМОУГОЛЬНОГО СЕЧЕНИЯ

The article provides information about the tests of rectangular cross-section reinforced concrete beams made of high-strength steel-fiber concrete on combined torsion and bending. Given information contains the main results: a diagram of the cracks with an indication of their opening width, the values of support reactions at the moment of cracking and at the moment before destruction. It was found that as the load is applied in beams made of high-strength steel-reinforced concrete, in the case of several cracks at the first stage, there is one crack increases. The beams are modeled in the design complex and given description of the main design parameters. The results of the calculation are presented and a comparative analysis of the results obtained with the experiments results. It is noted that the adopted models in the computational complexes require the development of subroutines and refinement.

Use of Rice Husk and Rice Husk Ash as a Replacement for Cement with Use of Additional Steel Fibres in Concrete

Use of Rice Husk and Rice Husk Ash as a Replacement for Cement with Use of Additional Steel Fibres in Concrete

Deformability of Steel-Fiber Beams with External Tape Reinforcement

In 2013, the Lviv National Agrarian University patented the construction of a steel-fiber concrete beam, additionally reinforced with an external steel ribbon armature with end anchors. This technical solution allows reducing the cost of the structure by reducing the complexity of its manufacture, due to the absence of a reinforcing frame in the structure. The purpose of this work is to develop proposals for a refined calculation method of deflections of steel-fiber concrete beams with tape reinforcement on the basis of our experimental studies. 3 beams with dimensions 1500x150x60 mm were manufactured. Beam B-1, reinforced with steel tape 1500x60x3 mm with end stops, did not contain fiber. Beams BF-2 and BF-3 in addition to the specified reinforcement contained fiber, corresponding the coefficient of fiber reinforcement by volume, ρfν = 1,5% i 2% respectively. Compressed prisms of 400x100x100 mm and stretched samples of 700x100x60 mm were also tested to determine the mechanical characteristics of concrete and steel-fiber concrete. Loose beams with a working run of 1400 mm were tested with concentrated force applied along the middle of the length. Mass production fiber produced both in Ukraine and abroad with bent ends HE 1050 1 mm in diameter and 50 mm in length was used for reinforcement. The percentage of fiber reinforcement by volume of concrete beams was taken ρfν = 1.5% and 2% to provide enough bearing capacity of the inclined sections. The cement of grade 400 (activity 42.3 MPa) of the Ivano-Frankivsk plant was used to obtain C20 /25 concrete. The test samples were made of fine-grained concrete containing sand from the Yasinets quarry with a fineness modulus of not more than 2.5. Mixtures for beams were made in a forced mixer. The composition of the mixture was chosen so that the settling of the cone did not exceed 4-6 cm and that the fiber did not settle to the bottom of the form. The composition of the mixture per 1 m3 of the mixture was as follows: cement - 549 kg, sand - 1647 kg, water - 285,5 l. The deflections of the steel-concrete beams were smaller than the steel-concrete beams at equal moments. For example, at the moment of 210 kN·cm the experimental deflection values of beams B-1, BF-2 and BF-3 were equal to 0.116; 0.081 and 0.064 cm, and at the moment 420 kN·cm - 0.380; 0.213 and 0.140 cm, respectively. In this paper, it is proposed to determine deflections using the Mora integral and taking into account the results of the calculation of beams by deformation method. The ratio of theoretical and experimental values of deflections was equal to 0.93 … 1.14.

Bearing capacity of steel-fiber-concrete slabs with biaxially prestressed reinforcement

The aim of the research is to obtain new experimental data of biaxially prestressed steel-fiber-concrete slabs under transverse loading and to develop a method for calculating their bearing capacity.
 Experimental-theoretical studies of biaxially prestressed steel-fiber-concrete slabs under the action of a uniformly distributed load were performed. Experimental studies were performed on plates measuring 40x800x800 mm with prestressed reinforcement Ø5Bp-II in two directions. Samples of the first series were reinforced with a mixture of steel fibers of STAFIB 50/1.0 and STAFIB 30/0.6 with anchors at the ends, the percentage of which was 0.5% by volume of each fiber. The samples of the second series contained 1.0% by volume of NOVOKON URW 50/1.0 corrugated fibers.
 A method for calculating steel-fiber-concrete (SFB) slabs based on the deformation method is proposed. This takes into account the real diagram "σ-ε" for uniaxial and biaxial compression of steel-fiber-concrete and increase the compressive strength of steel-fiber-concrete under conditions of biaxial compression. Stress losses in the reinforcement from creep and shrinkage deformations of steel-fiber-concrete are also taken into account. The results of calculation of experimental samples and their comparison with the results of experimental researches are given. They showed sufficient convergence. The difference was 1.1… 2.5%. It is established that the bearing capacity of biaxially prestressed slabs is 1.55… 1.61 times higher than unstressed slabs and 42.4… 55.5% higher than uniaxially stressed slabs.

Behavior of conventional and fibered concrete shear walls during earthquake, an analytical simulation in SAP2000

The investigation of this paper was about non-liner behavior of shear walls against seismic wave by using conventional and fibered concrete. Case of earthquake study was Iripina 1980, Italy with Ms = 6.9 and fourth kind of shear walls with glass fiber, basalt fiber, steel fiber concrete and conventional concrete shear walls simulated in SAP2000 with dynamic analysis method. Analysis shows that glass fiber concrete and conventional concrete shear walls had similar behavior, also these shear walls had more suitable response. All shear walls behavior were same at the beginning of earthquake but at the end of earthquake basalt and steel fiber concretes had a lot of displacement. Furthermore, behavior of steel fiber concrete shear wall could not return at the last moments of earthquake. Beside modulus of elasticity and compressive strength had most effect on reaction of shear walls such that modulus of elasticity was the cause of doing linear behavior of shear walls during all times of earthquake, on the other hand compressive strength had most efficiently in dissipation energy. Best result in earthquake was with conventional concrete due to modulus of elasticity and compressive strength.

Mechanical properties of concrete beam with steel fiber and baxuite residual

There is lot of new materials are used in current construction work. This changes due to the improve the performance, to minimize the environmental causes, to use waste materials effectively. The materials mostly is used as a partial replacement of the conventional materials. In this study we are using steel fibre as a additive and bauxite residual is the replacement of binder. The cement was replaced (0%, 2%, 5%, and 10%) with bauxite residual. In addition to the concrete steel fibre (0%, 0.5%, 1%, 1.5%, and 2%) is added. The experimental investigation determines the mechanical properties such as ultimate load, deflection, flexural strength and failure mode of reinforced concrete beams. The addition of steel fiber and bauxite residual in concrete increase the mechanical properties of the concrete beam.

Study and Comparison of Characteristics of Models of Hollow-Core Slabs, Reinforced Concrete and Steel-Fiber Concrete

Two models of hollow core slabs were tested: reinforced concrete and steel fiber concrete. When designing slab models, the proportions of full-sized structures were preserved for the further possibility of correct data comparison. As a result of testing models of hollow core slabs, it was found that the bearing capacity of a slab with combined reinforcement is 24% higher than that of reinforced concrete, the deflection is 36% less, and the crack resistance is 18% higher. The use of steel fiber made it possible to avoid the brittle fracture of a steel fiber reinforced concrete slab, which was observed in the model of a conventional reinforced concrete slab.

Concrete grade change in the layers of three-layer steel fibre reinforced concrete beams

Purpose: Determine the state of stress-strain, formation and development cracks, three-layer beam diagrams of load-compression stress, load-tension stress, load-vertical displacement relationships with a change in concrete grade. Design/methodology/approach: This paper presents the results of an ANSYS numerical simulation analysis involving stress-strain state and cracking of the steel fiber concrete layers of three-layer reinforced concrete beams with the upper and lower layers. With a cross-section of 150x300 mm, a total span of 2200 mm and an effective length of 2000 mm, the middle is a normal concrete layer. Under two-point loads, all the beam samples were tested. The research simulated three-layer concrete beams in different layers of beams with a change in concrete grade, and compared with and without the use of steel fibers in layers of concrete beams, including the nonlinearity of the material considered. Findings: A diagram of the formation and development of cracks in three-layer concrete beams has been constructed by the study results, determining the load at which the concrete beams begin to crack, the load at which the concrete beams are damaged. In the middle of three-layer steel fiber reinforced concrete beams, load-compression stress, loadtension stress, load-vertical displacement relationships are established. Study results show that these three-layer concrete beams appear to crack earlier than in other cases in cases 2 and 3, but the beam bearing capacity is damaged at 67 kN, the earliest in case 3. And case 6 at 116 kN is the latest. The effects of case 1 and case 3 are small compared with and without the use of steel fibers in cases, while the effects of case 5 and case 6 are very high. Research limitations/implications: The research focuses only on the change of concrete grade in the layers, but the input parameters affecting three-layer steel fiber concrete beams have not been researched, such as the number of tensile steel bars, tensile steel bar diameter, steel fiber content in concrete, thickness variation in three-layer concrete beam layers, etc. Practical implications: Provides a result of experimental study and ANSYS numerical simulation in multi-layer steel fiber concrete beams. Originality/value: The analysis of multi-layered steel fiber concrete beams using experimental and simulation methods shows that other parameters influencing the beams will continue to analysis the working stages of three-layer beams.

Flexural Behavior of Composite Concrete Slabs Made with Steel and Polypropylene Fibers Reinforced Concrete in the Compression Zone.

The paper presented aimed at examining the effect of a fiber-reinforced concrete layer in the compressed zone on the mechanical properties of composite fiber-reinforced concrete slabs. Steel fibers (SF) and polypropylene fibers (PP) in the amount of 1% in relation to the weight of the concrete mix were used as reinforcement fibers. The mixture compositions were developed for the reference concrete, steel fiber concrete and polypropylene fiber concrete. The mechanical properties of the concrete obtained from the designed mixes such as compressive strength, bending strength, modulus of elasticity and frost resistance were tested. The main research elements, i.e., slabs with a reinforced compression zone in the form of a 30 mm layer of concrete with PP or SF were made and tested. The results obtained were compared with a plate made without a strengthening layer. The bending resistance, load capacity and deflection tests were performed on the slabs. A scheme of crack development during the test and a numerical model for the slab element were also devised. The study showed that the composite slabs with fiber-reinforced concrete with PP in the upper layer achieved 12% higher load capacity, with respect to the reference slabs.

Concrete and Fiber Concrete Impact Strength

The results of experimental studies of the impact strength of samples of concrete and steel fiber concrete are presented. For dispersed reinforcement, three types of steel fiber were used - with bent ends, wave and flattened. Tests were conducted to determine the static and dynamic bending strength, and then - impact tests on the pendulum headstock MK-30. It was found that the impact strength increases significantly in the presence of fiber, but the type of fiber has almost no effect on it. Since specimens reinforced with a fiber content of 1.0 and 1.5% differ slightly in impact strength, 1.0% dispersed reinforcement in volume is recommended, both under static and dynamic loads.

Steel fiber concrete. Constructions. Terminology

The article discusses the terms and definitions that are increasingly appearing in the open press and on the Internet, confusing well-established concepts. The purpose of considering terminology issues is an attempt to draw the attention of the community of builders – scientists and practitioners to the inadmissibility of inaccuracy and incorrect choice of terms and definitions in the technical, scientific and even regulatory literature. The article discusses the transformation (changes) of terminology in the field of dense concretes, reinforced concrete structures, as well as structures based on a building composite – steel fiber reinforced concrete. In particular, concrete is a composite, reinforced concrete is not a collective name for reinforced concrete structures and products, but material, moreover, is composite. At the same time, steel fiber concrete is a hardened concrete. This approach is an important reason for restraining widespread use in the practice of building structures based on steel fiber reinforced concrete. These terms are often used in the open press, depriving the discussed topics of physical meaning, and, as a result, the impossibility of obtaining the expected result. At the same time, the open press provides information on composite materials, the peculiarities of creating and managing their properties. The article presents the established generally accepted terms and definitions that correspond to the physical nature of concrete, reinforced concrete structures, composite materials and structures based on composite – steel fiber reinforced concrete. The definition of composite materials, the principles of their creation, as well as the features of the composite – steel fiber reinforced concrete and methods of forming its structure are presented. A method is shown for obtaining the properties of steel fiber reinforced concrete in accordance with the stress-strain state of the developed structural element and creating structures based on it with properties specified in accordance with the conditions of their operation and having technical and economic indicators that exceed those of standard structures – analogues.

Experimental Study of Strengthening of RC Columns with Steel Fiber Concrete

This study introduces an experimental program to investigate the performance of concrete wrapping jackets reinforced by steel fibers used for retrofitting of the square and circular RC columns under axial loads. Ten columns divided into two groups; the first group included seven square columns while the second group involved three circular columns. The experimental study included testing the columns with varied parameters such as cross-section shape, type and aspect ratio of steel fibres, jacket thickness, and using several techniques for retrofitting the column such as strengthening by plain and reinforced concrete jackets. The selected parameters affected the compressive behavior of confined columns high strength concrete jackets. The obtained results revealed that all strengthened columns with square cross-section appeared maximum strength greater than a circular one. Using several types of concrete jacketing promotes the load-capacity of the column with a clear improvement in the ductility. Increasing thickness appeared increasing in the load-carrying capacity in comparison with the reference column. Using the straight fibres showed better enhancement in the load capacity than the hooked ones. The main result was the failure mode was different from unstrengthen columns which showed more crushing in the concrete core with an increase in thickness.

Reinforced concrete beams strengthened with steel fiber concrete

The aim of the study at exploring joint behavior under load of steel fiber concrete strengthening jackets (SFRC) and reinforced concrete beams at all loading stages. It is necessary for further development of calculation methodology for this strengthening method for members subjected to bending. Experimental results were obtained for assessment of strength, stiffness, crack resistance and failure behavior with a crack propagation pattern for the examined 4 samples (two with strengthening jackets and two reference non-strengthened samples). It has been found that the use of an SFRC jacket 45 mm in thickness with 2.5% fiber content (at the rate of 196 kg per cubic meter) increases the failure load by 20%, the stiffness – 3.4–11 times in the course of loading, and crack resistance – about 2.6 times. The results obtained were compared with the computer simulation in ANSYS PC: the discrepancy between the cracking load, failure load and deflection values for full scale samples and the computer model were found to be within 6.3 %.