Percentage Of Steel Fibers Research Articles

Effect of steel fibers on the interfacial shear strength of flyash and GGBS based geopolymer concrete activated with water glass

Concrete, a fundamental construction material, heavily relies on cement, manufacturing process of cement results in significant CO2 emissions, posing environmental concerns. Hence, exploring substitutes for cement becomes imperative to mitigate CO2 emissions. Geopolymer materials emerge as promising alternatives capable of entirely replacing Ordinary Portland Cement (OPC). However, these materials necessitate activators to initiate the polymerization reaction. While Na2SiO3 and NaOH are commonly utilized as activators, their cost-effectiveness is questionable. Moreover, when Ground Granulated Blast Furnace Slag (GGBS) reacts rapidly with these activators. To address these issues and streamline concrete production, “water glass” is employed as an activator, offering a solution to avoid rapid setting and economize the production process. In other hand the production of mass concrete structures, interfaces and joints critical points where cracks may develop. To ensure monolithic behavior, shear ties were advised at the interface in order to establish strong bond strength. However, the efficiency of construction could be decreased by adding more shear ties. The purpose of this study is to evaluate the interfacial shear strength of Geopolymer concrete (GPC), With the addition of different percentages of steel fibers 0.5, 1%,and 1.5%, with shear ties at the interface of push-off specimens. The findings reveal that it is viable to replace two shear ties with one 8 mm-2L shear tie and 1% crimped steel fibers of 30 mm length.

Durability Studies and Stress Strain Characteristics of hooked end steel fiber reinforced ambient cured geopolymer concrete

Abstract For conventional concrete, the use of fibers has proven to improve the strength properties of the material. However, in the case of ambient cured geopolymer concrete, there are limited studies that explore the application of fibers, in particular, the use of hooked end steel fibers. Further, it is important to study the durability properties of geopolymer concrete with fibers, since it will influence the service life of the structures in practice. Therefore, in the present study, fiber-reinforced geopolymer concrete was synthesized using fly ash, GGBS, hooked end steel fibers, and alkaline solution made with Na2SiO3 and NaOH. The percentage of steel fibers varied in the range of 0.5% to 2% with an increment of 0.5% by volume fraction of the binder. The precursor materials were characterized using techniques such as X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscope (SEM). Durability studies like water absorption, drying shrinkage, sulphate attack were studied. In addition, the elastic constants were determined through stress strain behaviour of geopolymer concrete in uniaxial compression. The results of the experimental study showed that the addition of hooked end steel fibers influences the strength of geopolymer concrete up to an optimal percentage, which was found to be 1%. Furthermore, in terms of durability properties, the addition of fibers exhibited better results in terms of resistance to water absorption and chemical attack, and this was validated by the microstructural studies, where the specimens with hooked end steel fibers revealed much denser hardened geopolymer matrix when compared to the mixes without fibers.

Axial behavior of UHPC columns with new emerging mixtures and varying confinement

Using advanced materials to optimize designs and make structures resilient is becoming of crucial importance. Advanced rapidly growing materials with superior mechanical properties, like ultra-high performance concrete (UHPC), can make structures better in terms of strength and service life when compared to conventional concrete. Behind the excellent performance of UHPC stands its dense packing theory and usage of steel fibers or even carbon nanofibers (CNF) in emerging UHPC mixtures. UHPC is mostly used in small-scale applications like bridge field joints and overlays, but research is extending UHPC to full structural applications such as girders and columns. To expand existing knowledge on UHPC columns and add new results from emerging and recently commercialized UHPC mixtures, this study uses, for the first time, two new UHPC mixtures with white cement and CNF enhancement to investigate axial behavior of nine full-scale columns with varying confinement. An extensive experimental program considers two groups of columns from two different mixtures with several other variables such as transverse reinforcement detailing, cross-section, and percentage of steel fibers. The paper presents results from companion material tests along with a detailed discussion of the global and local behavior of the columns, i.e. force, axial strains, reinforcement strains, and stiffness. Test results are interpreted in light of existing ACI 318 Code provisions and guidance is provided for axial design capacity estimation and transverse reinforcement detailing.

A design methodology for fibre reinforced concrete elements in serviceability conditions integrating tension softening and stiffening effects

This paper proposes a design methodology to derive an analytical bilinear moment‒curvature diagram (Mana–χana) for the cross-section of fibre reinforced concrete (FRC) elements that also includes conventional steel flexural reinforcement (R/FRC). This bilinear diagram is obtained by determining the post-cracking tensile capacity of FRC (NtcFRC), which integrates not only the tensile stiffening capacity of the FRC surrounding the conventional flexural reinforcement due to the bond stress transference between this reinforcement and FRC, but also the tensile softening of the cracked FRC out of this zone. This Mana–χana is defined by two points, the first corresponding to the cracking moment and its corresponding curvature (Mcrana,χcrana), while the bending moment of the second point of this diagram (Muana) is a multiple of the analytical cracking moment (CuMcrana), where Cu is dependent on the fibre volume percentage (Vf). The curvature corresponding to Muana,χuana, is obtained by assuming the flexural stiffness of a fully cracked RC section. Therefore, the Mana–χana is determined by geometric and material properties of directly assessed by a designer.For demonstrating the applicability of the proposed design methodology, a database of beams of distinct cross-section aspect ratios and compressive strength classes, reinforced with different percentages of steel fibres and reinforcement ratios of conventional steel bars was established. By using the bilinear Mana–χana, and applying the principle of virtual work, the deflection of these beams was estimated with sufficient accuracy for design purposes, when compared to experimental records. Although the formulation has been applied to beams made by steel fibre reinforced concrete (SFRC), it is conceptually general and applicable to elements of concrete reinforced with other types of fibres.

Effect of steel fibers and the fiber-concrete adhesion stress on the nonlinear shear behavior of beams

In this article, a theoretical model in nonlinear elasticity is presented to analyze the influence of the percentage of steel fibers and the effect of the fiber-concrete bond stress on the shear force at the rupture of beams subjected to the combined effect of bending moment, normal force, and shear force. For a given beam section, it is defined by a succession of layers of concrete and longitudinal steel elements. Each layer is defined by its height hi, width bi, and position relative to one end of the section YGi. Each longitudinal steel element is also defined by its cross-sectional area and position relative to one end of the section. The steel fibers are defined by volume percentages of 0.5%, 1%, 1.5%, and 2%, taking into account the mechanical nonlinearity of the materials. This model is based on the multilayer analysis of sections and an iterative solution procedure for each layer and each section, considering a given longitudinal deformation state and shear stress. The global equilibrium of the sections is analyzed under the assumption of flat longitudinal deformations but with, in principle, an interdependence of longitudinal normal stresses and shear stresses. In this study, using the principle of virtual work, equilibrium equations for deformations and stresses, as well as partial compatibility equations between concrete deformations and mean deformations, are derived. Comparative examples between ordinary reinforced concrete beams with variable shapes and reinforcement details, and those reinforced with steel fibers, are presented to demonstrate the accuracy of the proposed model for simulating the nonlinear shear response of beams.

Behaviour of Steel Fiber Reinforced Concrete in Deep Beam for Flexure

Use of deep beam in construction field saves money as well as increase the strength of structure. Reinforced concrete deep beams have very useful structural application such as piles-caps, water tanks and tall buildings. Addition of steel fibers gives good results to both load carrying capacity and increase the flexural strength of the deep beam. Steel fiber is kind of newly developed reinforced material for concrete widely adopted globally now a day, which features good performance in anti-crack, pressure resistance, anti-abrasion bending toughness, affinity with concrete, reinforcement for construction element compjonent and lengthy service life. Thus by using the steel fiber reinforced deep beam with varying percentage of steel fibers increases the first crack load and the ultimate load which gives the high flexural strength to the structure and achieves economy. This paper includes study of behaviour of steel fiber reinforced concrete in deep beam with advantages, disadvantages, properties of steel fiber etc. Keywords: Steel Fiber, Beam, Anti-Abrasion Bending Toughness, Affinity, Reinforcement

Mechanical Properties of Rigid Pavements Incorporating Different Percentage of Steel Fiber

Nowadays, rigid pavement construction has widely used in road construction industry. Although rigid pavement is widely used in road construction, it tends to fail within time due to many reasons. Fatigue is the important aspect in the rigid pavement design. Due to applications of the heavy loads fatigue occurs in the pavement in the form of micro cracks. Fatigue concepts which is an important parameter in cement concrete pavement and mainly failure occurs due to fatigue failure. As a result, it is crucial to optimize and improving concrete structures to suit diverse engineering requirements. This paper investigates the effect of steel fiber on the improvement of structural behavior such as compressive, tensile and also flexural stiffness performance of rigid pavements. In this respect, the concrete mix design accordance to Design of Normal Concrete Mix (DOE) method was employed in the preparation of the specimens. A series of concrete laboratory tests have been carried out to evaluate the mechanical properties of the concrete sample incorporating 1, 3 and 5% of steel fiber. As a result, the performance (compressive, tensile and flexural) of modified rigid pavements improved remarkably 15-60% with 5% additive of steel fibre at 7 and 18 days curing time. Based on these studies, the addition of steel fiber reinforcement into the rigid pavements has a significant effect on mechanical properties of reinforced concrete mixture.

Global performance indicator (GPI) approach to predict the steel fiber reinforced concrete strength with error analysis

ABSTRACT The main aim and objective of the present research is to forecast the strength of steel fiber reinforced concrete (SFRC) using four mathematical models developed with five independent variables viz. control strength, aspect ratio, percentage of steel fiber, water to cement ratio and aggregate to cement ratio. These models provide the best model with the best performance to be determined by error analysis. For obtaining the experimental data, concrete cubes of size 150 mm x 150 mm x 150 mm are tested under compression. For flexure strength, beam specimens of size 150 mm × 150 mm x 700 mm are casted with steel fiber reinforced concrete. Thus error analysis is performed for exponential mathematical models, log-linear models, analytical models and Artificial Neural Network (ANN) models to compute response variables considered in the study. The calibrated model was analyzed, compared, and ranked using the Global Performance Indicator (GPI). Difference between standard deviation of predicted and experimental data is found to be -0.082 for exponential model and for ANN model it is computed as 2.771. The exponential mathematical model shows a higher GPI value as 0.67, whereas ANN model exhibits lower GPI value as -6.94. The novelty of the work is that, this research compares the models based on the mean value, mean error, % error, mean square error (MSE) and root means square error (RMSE) of the model when compared with field data. Experimental results are also provided for steel fiber reinforced concrete (SFRC). The effectiveness of GPI approach to predict the fiber reinforced concrete (FRC) strength is discussed.

The performance of steel fiber reinforced concrete as structural elements of a seismic resistant three-story low-cost housing using SAP 2000

Seismic activity is a looming threat in many regions around the world. Hence, pursuing low-cost housing solutions that can withstand seismic forces while remaining economically viable is critical. This research is motivated by the urgent necessity to create innovative materials and cost-effective design methodologies that can withstand the forces of devastating earthquakes. This study explores the effectiveness of steel fiber reinforced concrete (SFRC) as a structural element in a three-story low-cost housing building. SFRC incorporates small and hooked steel fibers into concrete, improving its mechanical properties, such as tensile strength, toughness, and ductility. This study aims to replace traditional reinforced concrete with SFRC in building columns and beams and assess its seismic performance using Finite Element Method (FEM) analysis conducted through SAP 2000 software. This study conducted experiments using concrete mix samples with different percentages of steel fibers (0%, 0.3%, 0.5%, and 0.7% by weight) and found that the 0.3% SFRC sample exhibited the highest compressive and flexural strength. Four models evaluated the cost-effectiveness of SFRC compared to the control sample with regular concrete. The analysis revealed that Model (3), featuring 250 x 300 mm columns with SFRC, significantly decreased concrete volume and rebar quantity. It resulted in a 13.79% reduction in structural costs compared to the original plan. Overall, the study highlights the potential of SFRC to enhance the mechanical properties of concrete and reduce costs in seismic-resistant construction projects. By incorporating SFRC, engineers can improve buildings' structural stability and performance, particularly in earthquake-prone regions.

Experimental and numerical investigation of steel fiber concrete fracture energy

This research investigates the influence of steel fibers on the mechanical properties and behavior of concrete through a combination of numerical simulations and laboratory experiments. A series of numerical models were developed and validated against experimental results, employing circular-shaped aggregates to ensure model accuracy. The load-CMOD diagrams revealed that an increase in the percentage of steel fibers led to significant improvements in the tensile strength and energy absorption of the concrete specimens. The presence of steel fibers acted as an effective barrier, inhibiting crack propagation and enhancing the energy absorption capacity of the concrete. However, beyond a certain fiber percentage (approximately 4%), the increase in energy absorption became limited due to reduced bonding forces between the fibers and cement mortar, resulting in premature failure of the specimens. The numerical models provide valuable insights into the behavior of fiber-reinforced concrete, facilitating the optimization of concrete design for various engineering applications. This study contributes to a broader understanding of fiber-reinforced concrete behavior and underscores the significance of selecting the optimal fiber content and distribution for specific construction scenarios. Further research is encouraged to explore the complex mechanisms of fiber-matrix interaction in concrete for developing more resilient and durable concrete structures.

Mechanical and Durability Evaluation of Hooked End Steel Fibers Reinforced Concrete

Steel fibres reinforced concrete has recently been good alternative to normal concrete.This research seeks to explore the characteristic strength of high-performance concrete through the incorporation of hooked-end steel fibers, simultaneously evaluation their mechanical and durability attributes. In the experimental setting, multiple concrete mixes were meticulously prepared and examined, each containing different percentages of steel fibers varying from 0.5 to 2.0 percent. The percentages of fibres were used with the respect by volume of concrete. The primary objective was to ascertain the saturation point at which maximum strength is achieved and to identify any other pertinent factors. Five mixes were formulated, with one mix serving as the normal group, containing no fibers whatsoever. M30 grade concrete was employed in this investigation, incorporating steel fiber content ranging from 0.5% to 2.0%. Test specimens in the form of cubes, cylinders, and prisms were meticulously prepared and subjected to controlled laboratory testing following 28 days of water curing. Various mechanical properties, such as compressive strength, split tensile strength, and modulus of rupture, were assessed for all fiber percentages. Additionally, a durability assessment was conducted for period of 30 days to specimens containing 0% and 1.5% steel fibers, evaluating their resistance to acid, sulfate, and saltwater. Non-destructive tests, including rebound hammer and ultrasonic pulse velocity, were performed both before and after immersion to study the effects. The study’s findings revealed that high-strength concrete specimens containing fibers demonstrated a decreased occurrence of cracks, suggesting an improvement in ductility attributed to the inclusion of fibers in the concrete matrix.

Verification and Parametric Analysis of Shear Behavior of Reinforced Concrete Beams using Non-linear Finite Element Analysis

Many researchers have tackled the shear behavior of Reinforced Concrete (RC) beams by using different kinds of strengthening in the shear regions and steel fibers. In the current paper, the effect of multiple parameters, such as using one percentage of Steel Fibers (SF) with and without stirrups, without stirrups and steel fibers, on the shear behavior of RC beams, has been studied and compared by using Finite Element analysis (FE). Three-dimensional (3D) models of (RC) beams are developed and analyzed using ABAQUS commercial software. The models were validated by comparing their results with the experimental test. The total number of beams that were modeled for validation purposes was four. Extensive parametric analysis has been carried out on another twelve beams to explore the influence of specific parameters, such as using different strengths of concrete, different flexural reinforcement bars, and laminate in the shear regions. It is concluded from the results that when a different compressive strength was assigned to RC beams, a decrease by 31 of beam ultimate strength was recorded when using C25 concrete strength. On the other hand, an improvement of 29% was observed by assigning concrete compressive strength C50. As well as another decrease of 18 and 26 kN was observed when GFRP was used with beams that had stirrups and beams that had both stirrups and SF. However, the beams recorded a higher number for ductility with using GFRP. In addition, using laminate with the beam that had both stirrups and SF was not beneficial; hence, the failure load was increased by only 3%, particularly with the beam that had both stirrups and SFs

Characteristics and neutron imaging of capillary water absorption for metakaolin and steel fiber reinforced slag based-geopolymer mortars

The manufacturing of cement consumes energy and natural resources of raw materials, and emits large amounts of CO2. Geopolymers are eco-friendly building materials that have the potential to replace cement-based building materials. We used neutron radiography to report new data on water absorption and distribution in metakaolin (MK) and steel fiber reinforced slag-based mortars for the first time. Due to contradictory studies on the influence of adding steel fibers to slag-based geopolymers on compressive strength and the limited research on water permeability, workability and sorptivity, new results were presented. Alkaline-activated MK and steel fiber reinforced slag -based geopolymer mortars were prepared. The neutron radiography (NR) technique was used to investigate capillary water absorption in the mortars. The fresh and mechanical strengths of the mortars, as well as their permeability, workability and sorptivity, were determined. The compressive, flexural, and splitting tensile strengths, as well as the water permeabilities, increased, whereas the workability decreased as the steel fiber percentage in slag-based mortars increased. The results showed that the addition of steel fiber at volume fractions of 1%, 2%, and 3% increased the −7 and 28 days compressive strengths for the slag-based mortars by 44.7%, 50.7%, and 57.1% and 41.9%, 50.2%, and 55.1%, respectively. The NR results revealed that the resistance to water penetration in reinforced slag-based mortars is greater than that of MK. The addition of steel fiber introduced inhomogeneity in the matrix of the reinforced samples and created water-accumulating regions. Water proceeded regularly in the Mk samples but irregularly in the slag-based mortars. The capillary absorption factors k for Mk and slag-based mortars with steel fiber at volume fractions of 1%, 2%, and 3% were found to be 0.37 cm min−1/2, 0.2 cm min−1/2, 0.17 cm.min−−1/2, 0.19 cm min−1/2, and 0.2 cm min−1/2, respectively. According to NR, the optimal percentage of steel fibers in the slag-based mortar impeding water flow is 1%–2%. Steel fiber used at a high proportion to slag-based mortars increased sorptivity. To best fit the results at high absorption times, the second Fick's law of diffusion can be used.

Structural Performance of Ferrocement Panels under Low- and High-Velocity Impact Load.

The primary objective of this experimental study is to examine the response and energy absorption capacity of ferrocement panels exposed to low- and high-velocity impact loads. The panels are reinforced with two different types of mesh layers, namely, welded wire grid (WWG) and expanded wire grid (EWG), with varying percentages of steel fibers (SF). The ferrocement panel system is made up of cement mortar reinforced with 0-2% SF with an increment of 1% and wire grid layers arranged in three different layers 1, 2, and 3. A consistent water-cement ratio (w/c) of 0.4 is maintained during mortar preparation, and all panels are subjected to a 28-day curing process in water. The study utilized square-shaped ferrocement panels measuring 290 mm × 290 mm × 50 mm. The panels are exposed to repeated impact blows from a 2.5 kg falling mass dropped from a height of 0.80 m. The count of blows necessary to commence the first crack formation and the cause of ultimate failure are recorded for each panel. The study reports that an increase in SF content and the number of wire grid layers increased the number of blows needed for both the first crack and the ultimate failure. In the high-velocity impact test, 7.62 mm bullets are fired at the panels from a distance of 10 m with a striking velocity of 715 m/s. The study observed and analyzed the extent of spalling, scabbing, and perforation. The results showed that an increase in fiber content and the number of wire grid layers led to a decrease in the area of scabbing and spalling compared with the control specimens. It was also possible to see the mode of failure and crack pattern for impacts with low and high velocities.

Experimental Investigation on the Impact of Micro-Steel Fibers on the Flat Slabs' Punching Shear Resistance

This research examined the effects of micro-straight steel fiber percentage and column form on the punching shear of SFRC slabs. Fibers made of micro steel with a diameter of 0.2 mm and a length of 13mm with an aspect ratio equal to 65 were used. The fiber content varied between 0.5%, 1%, and 1.5% by volume. Four different types of concrete mixes were adopted and tested. Experimental results showed that when the percentage of steel fibers in SFRC increased, its compressive strength, flexural strength, splitting tensile strength, and direct tensile strength improved. This investigation applied a monotonic load to eight cast slabs (two each of conventional concrete of square and circular column sections of the equivalent area while the other six slabs were made with steel fiber concrete. The dimensions of each slab were (920 x 920 x 80 ) mm. Each slab specimen had essential, edge-based support with square and round column sections. It has been demonstrated that slabs with square column sections endured a relatively higher ultimate load than slabs with circular column segments when the steel fiber dosage was 0.5% or 1.0%. Still, at a steel fiber dosage of 1.5%, circular column segment slabs approached the ultimate load of square column segment slabs. The heterogeneous behavior in concrete can be attributed to the random and unequal distribution of steel fibers throughout the material. There were only flexural fractures visible on the tensile face of the slab. New fractures emerged in the center of the slab as the load increased.

Influence of nano-coated micro steel fibers on mechanical and self-healing properties of 3D printable concrete using graphene oxide and polyvinyl alcohol

High ductility cementitious composite is one of the proposed new generations of concrete for use in 3D concrete printing with a large dosage of microfibers. This large volume of fibers negatively affects printed layers’ fresh properties and durability. It also increases the porosity of concrete and is not cost-effective. Accordingly, through an experimental program, this article introduces a novel coating technique to reduce the required quantity of fibers for 3D concrete printing. Polyvinyl alcohol (PVA) is used in the present study to help in coating graphene oxide (GO) nanomaterials on the surface of micro steel fibers. Compressive, direct tensile, and bending tests are considered for the mechanical properties. The self-healing property of the proposed mixture is also checked by applying pre-loading on direct tension and bending samples and followingly putting for the healing period. The results show that the nano-coating method improves the compressive and direct tensile strength of cement mortar so that this technique can be used to reduce the volume percentage of steel fibers to achieve the same mechanical characteristics. Also, promising findings were obtained for the self-healing properties of cementitious composites containing nano-coated fibers.

Compressive behavior of steel-polyethylene hybrid fiber reinforced cementitious composite

A hybrid fiber reinforced cementitious composite (HFRCC) was produced by mixing steel fiber (SF) and polyethylene fiber (PE) together in the cement matrix with an appropriate ratio. Under the same PE volume percentage, the effect of various SF aspect ratios (30, 50, 65, 83.3, and 108.3) and volume percentages (0%, 0.3%, 0.6%, and 0.9%) on the compressive behavior of HFRCC was experimentally studied. The results indicated that the aspect ratio and volume percentage of SF had little effect on the elastic modulus of HFRCC. With the addition of SF, the maximum increase of compressive strength and peak strain reached 33.82% and 24.29%, respectively. And the HFRCC presented maximum compressive strength and peak strain when the aspect ratio of SF was 108.3 and the volume percentage was 0.6%. In order to reveal the compressive constitutive relationship of HFRCC, a piecewise function was adopted based on the comparison of existing theory and furthermore in which the fiber reinforcing index, compressive strength, peak strain, and elastic modulus had been introduced. It is concluded that the proposed compressive constitutive model has more agreement with test data.

Performance of slag based recycled coarse aggregate concrete with steel fibers

Designers may lessen the impact of concrete on the environment while yet ensuring enhanced performance and higher durability by using slag cement, which has proven long-term performance advantages. However, in actual practice, concrete constructions use slag to replace OPC up to 30 to 50 percent of the time, depending on the uses. By using M sand in place of river sand, this study shows differences in the strength and durability parameters of concrete manufactured using 100% with slag cement. Mechanical and durability study was made on replacement of natural coarse aggregates (NCA) with 30, 45 and 60% of recycled coarse aggregates (RCA); Based on the study optimum percentage of recycled aggregates for slag based concrete is 45%. Thus to study effect of fiber on concrete 45% of natural aggregates replaced by recycled aggregates with and without Nano silica.This reduces the consumption of natural resources and adds some additional benefits from a structural and financial standpoint. Steel fibers are added at a rate of between 0.5, 1 and 1.5 percent by volume of cement to give it strength. In order to obtain the optimum percentage of steel fibres using slag cement, concrete grades M20, M25, M30 and M35 were used. Testing techniques such as the compression test, flexural test, spill tensile test, Rapid Chloride penetration test used to assess properties recycled aggregate concrete and also performed the life cycle assessment. From the experimental study 1% Steel fibers was optimum for both with and without Nano silica.

Compressive Strength Dependency on the Effect of Temperature Variation on the Percentages of Steel Fiber in Concrete

Aims: The aim of this study is to check the effectiveness of steel fiber on the compressive strength of concrete. Background: Fibers have long been used as building materials to improve the ductility, tensile, compressive, and flexural strengths of concrete. Although fibers have been known as an effective reinforcement material for concrete structures, it is also acknowledged to be a suitable alternative to reinforcement steel bars. Objective: The objective of this research is to investigate some engineering properties, the compressive behavior of steel fiber reinforced concrete (SFRC), and the effect of elevated temperatures of up to 1000°C on concrete. Methods: Various tests which included the slump test, compressive strength test, as well as heating tests were done. The workability (slump) and thermal effects of M20 SFRC were evaluated. Results: Based on the results obtained, it could be observed that the workability of the M20 concrete reduced with the increase in steel fiber (SF) content from 0% to 1.6% as values obtained were 80mm, 73mm, 67mm, 61mm and 55mm for SF contents of 0%, 0.4%, 0.8%, 1.2%, and 1.6% respectively. These values showed medium workability of the concrete according to ASTM C-143/C-143 M-03. Also, the addition of SF to plain M20 concrete greatly improved the compressive strength (ƒc) with the concrete strength at 26.89N/mm2, 30.41N/mm2, 32.85N/mm2, 35.90N/mm2 and 39.66N/mm2 after 28 days of curing for steel fiber contents of 0%, 0.4%, 0.8%, 1.2%, and 1.6% respectively. The f_c after heating the concrete mix to 1,000°C showed improved thermal resistance with 4.2N/mm2, 8.23N/mm2, 11.63N/mm2, 15.60N/mm2 and 17.20N/mm2 for SF contents of 0%, 0.4%, 0.8%, 1.2% and 1.6% respectively. Conclusion: The incorporation of steel fibers in the concrete mix decreased the workability of SFRC but increased its compressive strength and balling tendencies.

Workability and Flexural Strength of Recycled Aggregate Concrete with Steel Fibers

This study examined how concrete workability and flexural strength are affected by steel fibers and recycled aggregates. Steel fibers were used in doses between 1-5%, with an increment of 0.5%, and 50% of the natural coarse aggregates were replaced by recycled. Two mixes of conventional and recycled aggregate concrete without steel fibers were used as control mixes. Concrete mixes were prepared using 1:2:4 and 0.45 water-to-cement ratios. Workability was determined using the slump cone. Three prism specimens sized 500×100×100mm were prepared for each batch and cured for 28 days in potable water. After curing, the specimens were air-dried in the laboratory and tested to evaluate their flexural strength under two-point loading. The load and deflection were monitored at regular intervals until failure. A comparison of results with control mixes showed that as the percentage of steel fiber increased, flexural strength increased by 69% and deflection decreased by 66%. The use of steel fibers improved the flexural strength of the recycled aggregate concrete by 59%.