Waste Steel Fibers Research Articles

Enhancing Mechanical Properties of Alkali-Activated Slag SIFCON for Sustainable Construction Using Recycled Glass and Tire-Derived Waste Steel Fibers

This paper presents the outcomes of a study in which continuous steel fibers, recovered from scrap tires of vehicles, were used to prepare alkali-activated slag-based slurry infiltrated fibrous concrete (SIFCON). In this experimental study, the steel fibers used were 250 mm long, with varying fiber contents of 0%, 1%, 2%, 3%, 4%, and 5%. The alkali-activated SIFCONs were produced by activating ground granulated blast furnace slag (GGBS) with a mixture of sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) solutions. Mixtures with ordinary Portland cement (OPC) were also cast for comparison purposes. The feasibility of utilizing finely ground waste glass as a silicate source for chemical activator solution in alkali-activated SIFCONs was also investigated. In this context, two different molar concentrations of NaOH, namely 8 M and 14 M, were employed during production. As activators, one series of mixtures utilized sodium hydroxide and sodium silicate solutions, while the other series replaced sodium silicate with finely ground waste glass. As a result, three different waste materials were utilized in concrete. 30 different mixtures were cast and examined in the experimental study. Load–deflection curves were obtained in three-point bending test and mechanical properties of the mixtures such as compressive, splitting and flexural strengths, fracture energy, and toughness were determined. The flexural strength and toughness increased with the use of waste steel fibers. The continuous waste fibers derived from discarded tires yielded results comparable to commercially available fibers, demonstrating their effectiveness in enhancing mechanical properties. Depending on mix design, the alkali-activated SIFCON attained flexural strength exceeding 75 MPa and compressive strength surpassing 100 MPa. These results suggest that concretes incorporating a variety of waste materials can be effectively combined. This innovative approach bridges an existing gap in the literature by combining alkali activation, waste glass, and waste steel fibers, ultimately yielding a sustainable composite that outperforms normal concretes in terms of mechanical properties while promoting environmental sustainability. Test results demonstrate that it is possible to obtain concrete with comparable mechanical properties while primarily composed of by-products and waste materials. This approach marks a substantial step in achieving high-performance concrete that relies solely on waste or by-products.Graphical

Experimental study on mechanical properties and toughness of recycled steel fiber rubber concrete

Adding rubber particles to concrete can improve its brittleness, but it also significantly reduces its compressive strength. In order to maintain the compressive strength of concrete unchanged and enhance its tensile strength and toughness, waste steel fibers are added to rubber concrete (RC). This not only achieves the reuse of solid waste materials, but also achieves the goal of high-performance concrete. By adding different amounts of scrap steel fibers to three different strength grades of rubber concrete, scrap steel fiber rubber concrete (SSFRC) is formed. Compression strength, tensile strength, and flexural strength tests were conducted on SSFRC with different mix ratios. The toughness of SSFRC was evaluated by introducing the tensile compression ratio, flexural compression ratio, and toughness index. The microscopic characteristics of SSFRC were observed using scanning electron microscopy (SEM), and the strengthening and toughening mechanism of waste steel fibers on RC was analyzed. The results show that: adding rubber decreases the mechanical properties of concrete with various matrix strengths; adding steel fiber admixture causes a trend in the mechanical strengths of SSFRC with various matrix strengths to increase and then decrease; getting the greatest compressive strength at 1 % and the peak tensile and flexural strengths at 1.5 %; Steel fibers and rubber particles can cooperate at a specific admixture amount to increase the toughness of RC. The local hydration of the scrap steel fibers may have taken place, according to the microscopic morphology of the Transition zone at the interface between the matrix and the scrap steel fiber. In conclusion, the best mechanical strength enhancement effect and the best toughness of SSFRC are achieved at 10 % of rubber and 1.5 % of scrap steel fiber.

EXPERIMENTAL APPROACH FOR DEVELOPMENT OF SUSTAINABLE HYBRID GRADED FIBER REINFORCED CONCRETE BY CONSUMING LATHE WASTE STEEL FIBERS WITH GLASS FIBERS FOR ENHANCED MECHANICAL PROPERTIES

Local workshops generate large quantities of industrial lathe waste steel fibers, which the steel manufacturing industries find difficult to recycle because of their sharp edges. The utilization of lathe waste steel fibers as fiber reinforcement is sustainable in concrete because these fibers have the same properties as steel fibers. Furthermore, using combinations of ductile and elastic fibers improves strain capacity and resistance to pre- and post-cracking. This research employs hybrid fiber reinforcement technology, utilizing industrial lathe waste steel fibers and glass fibers in varying proportions, to bridge the micro and macro cracks in concrete specimens. This research was done to examine the physical (workability) and mechanical properties (compressive and flexural strength) of hybrid fiber-reinforced concrete. In this research different mixtures of hybrid fiber-reinforced concrete were cast and designated as M0, M1, M2, M3, M4, M5, and M6. The mixtures included lathe waste steel fibers at 0%, 0.50%, 1%, 1.5%, 2%, 2.5%, and 3%, and glass fibers at 0%, 0.15%, 0.25%, 0.45%, 0.60%, 0.75%, and 0.90%, respectively. The ASTM-standardised protocols were followed for all laboratory testing. The physical property results showed a decrease in the workability of concrete mixes as the percentage of lathe waste steel and glass fiber increased. This suggests that a higher percentage of lathe waste steel and glass fibers leads to a lower slump value. Consequently, the mechanical property results showed a gradual enhancement in the compressive and flexural strengths of hybrid fiber-reinforced concrete up to 2.5% lathe waste steel fibers and 0.75% (M5). Further incorporation causes a reduction in strength. The physical examination of fractured samples of hybrid fiber-reinforced concrete confirms that the lathe waste steel fibers yield a maximum strain before breaking down in the concrete matrix. Furthermore, lathe waste steel fibers broke rather than being pulled out, indicating a good bond with the concrete. It is recommended that up to 2.5% lathe waste steel fibers and 0.75% of glass fibers by the total weight of the concrete can be used as hybrid fiber reinforcement for optimum strength achievement.

Sustainability-driven application of waste steel and tyre rubber fibres as reinforcement in concrete: An optimization study using response surface methodology

Innovative use of waste materials has proven to be effective for improving concrete’s technical properties while eliminating the threat of environmental pollution. There is paucity of research regarding the combined use of Waste Steel Fibres (WSFs) and Waste Tire Rubber Fibres (WTRFs) in concrete. Thus, this study aimed to investigate the influence of WSFs and WTRFs as reinforcement in concrete and determine their optimal fractions for enhancing the concrete strength properties using Response Surface Methodology (RSM). WSFs of 0.3-1.5% with a 0.6% increment and WTRFs of 0.3-1.5% with a 0.6% increment by concrete volume as reinforcement in concrete with water-to-cement ratio (W/C) of 0.25–0.65 with 0.2 increment were designed using the Box-Behnken Design of RSM. A total of fourteen (14) concrete mixes with a design strength of 25 N/mm2 were prepared. The fresh and hardened properties (slump, density, water absorption, 7- and 28-day compressive and split tensile strengths) of concrete were determined using standard procedures. The RSM was used to evaluate the interaction between the concrete variables and identify their optimum combination which gave the peak values of responses. Furthermore, the characteristics and sustainability of the concrete under optimum variables were compared with that of the conventional concrete. The outcomes revealed that the inclusion of WSFs and WTRFs yielded concretes with maximum slump, density, water absorption and 28-day compressive and split tensile strengths of 25 mm, 2633 kg/m3, 5%, 41 N/mm2 and 4.54 N/mm2, respectively. The optimization technique showed the optimal variables combination which yielded the peak response values of WSFs (1.40%), WTRFs (0.66%) and W/C (0.54). The nominal variance with the absolute percent error of less than (9%) between the actual experimental verified results and predicted results for all the responses validates the predictability of the model. The split tensile strength and compressive strength increased by 28.33% and 48.85%, respectively at the optimum setpoint of variable with respect to the reference concrete. In addition, the WSFs and WTRFs-reinforced concrete exhibited lower embodied CO2 emission but the embodied energy and cost are slightly higher relative to conventional concrete. Nevertheless, the embodied energy of the concrete was significantly lesser than that of concrete that used individual fibers for reinforcement. Thus, the enhancement of concrete strength properties with the prospect for sustainable fibre-reinforced concrete production through the use of waste steel and tyre rubber fibres is feasible.

Improving sustainability of precast concrete sandwich wall panels through stone waste aggregates and supplementary

Precast concrete sandwich wall panels offer advantages such as design flexibility, ease of installation, cost-effectiveness, and energy efficiency due to the incorporated insulation layer, but regular concrete production has sustainability issues. This study aims to improve the sustainability of these panels by utilizing stone waste aggregates as a replacement for natural aggregates and supplementary cementitious materials as a partial replacement for cement. The panels were made with two concrete wythes reinforced with steel fibers and joined using basalt fiber-reinforced polymer (BFRP) connectors, with high-density expanded polystyrene (EPS) insulation (30 kg/m3) in between. Self-compacting concrete mixes with varying proportions of stone waste aggregates and supplementary cementitious materials were used. Full-scale wall panels were cast and subjected to flexural tests per ASTM standards, analyzing load-displacement curves, ultimate bearing capacity, and failure modes. The incorporation of steel fibers and stone waste aggregates resulted in substantial increases in failure load and flexural strength compared to controlled concrete panels, with the stone waste steel fiber panels exhibiting significantly higher maximum cracking loads and improved energy absorption and ductility. The inclusion of these sustainable materials, along with basalt fiber connectors and grooves in the EPS layer for mechanical interlock, prevented brittle failure modes and enhanced the composite action, leading to more ductile behavior under flexural loading. Utilizing sustainable materials like stone waste aggregates (100% replacement) and supplementary cementitious materials (30% replacement) in these panels can contribute to eco-friendly and efficient construction practices while maintaining adequate structural performance, paving the way for more sustainable building systems

EXPERIMENTAL STUDY ON STEEL FIBRE REINFORCED NATURAL AGGREGATE CONCRETE

The rising volume of pollution is a significant treat to achieving the United Nations goal for a sustainable society. Various approaches have been used to tackle pollution, including recycling wastes to completely new product or utilizing them to improve other materials. In this respect, this paper presents the results of experimental study conducted on waste Steel fibre reinforced natural aggregate concrete. Steel fibres sourced from waste tyre were utilized in this research. The fibres measuring 2, 4 and 6cm were utilized using dosage of 0.5, 1 and 1.5% by mass of cement. Iron molds measuring 150 x 150 x 150mm were used for concrete production and were demoulded after 24 hours and cured. The optimum 28 days compressive strength of 27.19 N/mm2 was recorded with 4 cm fibre length and 0.5% fibre content. This represented a 36.36% gain in the 28 days compressive strength of the concrete when compared to the control.

Experimental Study on Fracture Properties of Self-Compacting Concrete Containing Red Mud Waste and Different Steel Fiber Types

This study aims to investigate the effect of integrating red mud (RM) waste and different types of steel fibers on the fracture toughness characteristics of self-compacting concrete (SCC). A total of 24 specimens consisting of notched SCC beams with various steel fibers (measuring 100 × 100 × 500 mm) are subjected to a three-point bending test. This study examines five various fiber types characterized by varying shapes and aspect ratios. These fiber types include the hook-end fiber with lengths of 60 and 30 mm, the long straight fiber with lengths of 21 and 13 mm, and the flat-end fiber. Six concrete mixtures, each incorporating fibers with 1% of the volume percentage, are examined. RM is used at a replacement rate of 20% of the mass of cement. Another objective of the study is to analyze the mechanical and fresh characteristics of concrete. The findings indicate that the incorporation of steel fiber has an adverse effect on the fresh concrete characteristics of SCC. The presence of steel fiber results in enhanced mechanical properties, peak loads, and deflection at the point of failure, in addition to an increase in the crack mouth opening displacement. The fracture toughness of SCC mixtures is also influenced by the presence of steel fiber.

Torsional Behavior of Waste Fiber-Reinforced Concrete.

Factory made steel fiber and steel fiber derived from worn tires was used to develop cement concrete, which was subjected to torsional forces. A dedicated stand for torsion tests, allowing for the measurement of force, deflection, and torsion angle, was used. The test results showed that both the factory-made fiber and the waste steel fiber significantly improved torsional properties of the concrete matrix. The test results of specimens made with waste fiber were characterized by slightly worse results compared to factory-made fibers, but there was a significant improvement in torsional properties compared to samples without fibers. Taking into account the financial and environmental benefits, the application of waste steel fiber recovered from car tires could be an interesting alternative to using commercially sold steel fiber applied for the production of construction elements subjected to torsional forces.

Developing an eco-friendly cementitious grout using paper sludge ash and steel fiber recovered from waste tires

Cement is the most important component in cementitious grout production,andtt accounts for 7% of global greenhouse gas emissions. Reducing the amount of cement used in infrastructure and buildings is a desirable way to lower the total carbon footprint associated with grout production. relatedly, developments in manufacturing and transportation lead to the production of cars in large numbers, which in turn leads to an increase in the production of byproduct waste like waste tires, which are thrown away directly without recycling. Thus, this study aims to develop a novel sustainable grout by recycling paper sludge ash waste (PSA) and waste steel fiber (WSF) as partial cement replacements. This will help reduce grout production costs, minimize environmental pollution during cement production, and enhance landfill and waste management. The Grout mixtures used in this paper were prepared using ordinary Portland cement (OPC), WSF extracted from vehicle tires, PSA, and water. Different proportions of WSF(0, 1, 2, 3%) and PSA(5, 10%) were used in the weight of cement in designing sustainable grout. The mechanical properties of the sustainable grout were evaluated by examining extensive tests including flow tables, compressive strength, and flexural strength. The results showed that partially replacing the cement with 3% WSF and 1% WSP with 5% PSA resulted in a significant improvement in workability ,as well as a clear increase in compressive and flexural strength at an early age compared to the reference mixture.

Effect of waste steel fiber use on concrete behavior at high temperature

Recently, recycling of waste vehicle tyres which pose a significant risk to environmental health has become an important research issue due to environmental concerns worldwide. To handle the waste tyre pollution problem, recycling waste into new products and using waste to improve other materials’ properties can be considered. Waste vehicle tyres can be used in the production of energy and various materials, providing economic and environmental advantages. In this study, experimental studies were carried out on the use of waste tyre steel fiber (WS) obtained from the recycling of heavy vehicle tyres in concrete, including the goal of recycling and reducing the need for raw materials. In one experimental group, waste tyre steel was added to concrete at 0.4% by volume instead of fine aggregate, while in the other experimental group it was added at 0.8% by volume. In the study, in addition to mechanical analyses, many microanalysis experiments were carried out to understand whether there was a strong relationship between the results. The study was conducted at target temperatures of 400, 600 and 800 °C depending on the fire scenario for building and construction materials according to ISO 834 and ASTM E119 standards. Compressive strength losses and characterization changes in 15 cm cube plain concrete and composite concrete specimens exposed to targeted high temperatures for 60 minutes were compared in terms of strength. Ultrasonic pulse velocity (UPV), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential thermal analysis (DTA), X-ray diffraction analysis (XRD) and Fourier transform infrared spectroscopy (FTIR) analysis was also performed, as it was understood that there was not enough data in the literature regarding waste tyre steel fiber reinforced concrete. General results showed that fiber-added concrete made significant contributions to concrete performance at high temperatures.

EFFECT OF USING WASTE FIBERS ON THE STRENGTH PROPERTIES OF SUSTAINABLE REACTIVE POWDER CONCRETE

A bulk volume of waste tires, an underrated global resource, is disposed of in landfills worldwide. Extracting recycled steel fibers from these tires is an evolving trend nowadays. Reactive-Powder Concrete (RPC), the most recent generation of concrete produced in the early 1990s and possessing extremely high mechanical strength criteria, is a modified form of high-performance Concrete. This study looked into how the type and volume proportion of new and waste steel fibers affected the compressive, flexural, and impact strengths 
 of RPC when it was curried at high temperatures. Steel fibers (new and waste tire fibers) with volume fractions of 1%, 1.5%, and 2% were used to create RPC. It was clear that increasing the amount of steel fiber had a beneficial effect on compressive, flexural, and impact strengths. Also, the results showed that the outcomes of RPC having steel fibers sourced from end-of-life tires are similar to those of industrial steel fibers.

Experimental study on flexural strength of slurry infiltrated fibrous concrete (SIFCON) produced with various percentages of waste steel fibers recovered from used tires

Slurry Infiltrated Fibrous Concrete (SIFCON), a modified version of Fiber Reinforced Concrete (FRC), addresses the challenge of increased fiber volume fractions. Commercially produced steel fibers are typically used in FRC and SIFCON. Efforts to reduce energy use in making commercial steel fibers have led to seeking alternative sources. Vehicular tires are typically recycled when no longer usable, yielding steel fibers among the products. Emphasis lies in recovering steel fibers from used tires as part of resource recovery from waste. Experimental work explored flexural strength in SIFCON with waste steel fibers at volumes from 4% to 7%. The study extended to assess SIFCON’s flexural strength with commercial steel fibers at similar volumes, aiming to correlate with those from waste steel fibers. M20 grade concrete and SIFCON slurry matrix specimens were cast as reference mixes for comparison. The flexural strength of SIFCON specimens with waste steel fibers recovered from used tires notably surpasses that of reference mixes and is comparable to SIFCON specimens with commercial steel fibers. Additionally, the two-layer technique proves effective in SIFCON using waste steel fibers from used tires, up to 6% volume. The test results show successful production of SIFCON from waste steel fibers recovered from used tires.

The effects of waste iron powder and steel fiber on the physical and mechanical properties of geopolymer mortars exposed to high temperatures

Geopolymer (GP) concretes have the potential to be an excellent alternative to cement-based traditional concretes for more sustainable concrete production. GP concretes have advantages such as low production temperature, low energy consumption, low carbon dioxide (CO2) emission, and rapid strength gain. However, GP concretes, similar to conventional concretes, lose a large part of their residual strength and durability capacities when exposed to possible high temperatures such as fire due to the deterioration of their internal structures. One efficient way to minimize the loss of strength and durability properties of GP concretes subjected to high temperatures is to use various waste materials and fibers in GP mixtures. This study aimed to improve GP mortar's physical and mechanical properties by adding steel (ST) fiber and waste iron powder (WIP) to GP mixtures. This study fundamentally investigates the spreading diameters (SD), mass loss (ML), external surface changes, residual compressive strength (RCS) and residual flexural strengths (RFS), and microstructural properties of GP mortars reinforced with ST fiber and WIP before and after high-temperature effects. According to the results, although ST fiber and WIP negatively affected GP mortars' workability and reduced GP mortars' SD values, they significantly increased GP mortars' RCS and RFS capacities. At 800 degrees (C), the RCS and RFS capacity reductions of the S0 control sample were 83.30% and 75.27%, respectively.In contrast, the drops in the RCS and RFS capacity of the S6 sample, in which 20% of WIP and 2% of ST fiber were used in hybrid form, decreased by 70.72% and 65.31%, respectively. However, ST fibers and WIP slightly reduced the ML of the GP mortars after the high-temperature effect due to ST fibers and WIP being ineffective in preventing peeling on the sample surface. At 800C, while the ML of the S0 control specimen was 4.47%, the ML values of S1-S6 specimens where WIP and ST fibers were used in single and hybrid forms varied between 4.16% and 4.38%.

Mechanical properties of alkali-activated slag based SIFCON incorporating waste steel fibers and waste glass

This experimental study focuses on sustainable slurry infiltrated fiber concretes (SIFCONs) by utilizing alkali-activated ground granulated blast furnace slag (GGBS) and waste fibers. The waste fibers were high-strength steel fibers recovered from scrap tires. Additionally, waste glass was employed as a substitute for commercial sodium silicate activator, contributing to the reutilization of a waste material. Such an approach stands out for its use of various waste materials to achieve a high-performance concrete primarily composed of recycled materials. Literature survey indicate that there are no studies available on concrete primarily composed of waste or recycled materials. In this study, the molarities of the activators were selected as 8 M and 14 M based on a prior research. Due to the fiber geometry and the associated bulking effect, a maximum waste fiber content of 5 % was adopted, with increments of 1 %. Load–deflection curves of the specimens were obtained in the bending test. Various mechanical properties, including compressive strength, splitting tensile strength, flexural strength, and fracture energy, were determined for the mixtures. The mechanical properties of the alkali-activated mixtures were improved compared to those of the reference concretes. Based on the mixture proportions and materials employed, alkali-activated mixtures in the study achieved compressive strengths exceeding 120 MPa and flexural strengths approaching 30 MPa. Furthermore, significant enhancements in fracture energies were observed. The strengths of the mixtures with waste glass, however, were lower compared to the other mixtures. Nonetheless, in summary, the study shows the promising potential of waste steel fibers and waste glass for the production of alkali-activated slag SIFCON. This approach not only enhances cost-effectiveness, sustainability, and mechanical properties but also reflects a significant step towards achieving a concrete composition that relies solely on waste materials.

Performance and life cycle of ultra-high performance concrete mixes containing oil refinery waste catalyst and steel fibre recovered from scrap tyre

An economic solution to recycle spent equilibrium catalyst (Ecat) disposed of by petrochemical manufacturers and steel fibre recovered from scrap tyre would be their use in the production of structural concrete. In this study, the performance and life cycle of ultra-high performance concrete (UHPC) mixes containing these waste materials was examined. They were made using a total binder content of 1160 kg/m3 and also contained fly ash and silica fume in addition to Ecat and cement. Their average compressive strength at the end of 28 days was found to be above 150 MPa. The replacement of cement with Ecat reduced the CO2 emission and material cost of recycled steel fibre (RSF) reinforced UHPC samples by 15% and 6%, but there is no significant change in their compressive, flexural and split tensile strengths at the end of 28 days. Only 2% of the elastic modulus of these samples increased as a result of the addition of Ecat by weight of the binder. Ecat, an aluminosilicate material, is generally classified as a pozzolanic material, but its addition together with fly ash and silica fume in the UHPC mixture did not affect the strength gain properties. Based on our experimental findings, the use of waste materials including Ecat and RSF in the preparation of precast UHPC elements for explosion and earthquake resistant structures is recommended.

Flexural behavior of steel fiber reinforced concrete beams comprising coarse and fine rubber and strengthened by CFRP sheets

Despite having many advantages, using rubber to produce reinforced concrete members like beams is still restricted. When there is more waste tire rubber in concrete structures, rubber concrete's flexural and compressive strengths gradually decrease. However, this study used steel fibers to improve compressive strength and externally bonded carbon fiber-reinforced polymer (CFRP) sheets to increase flexural strength. Four groups of three reinforced concrete beams each were established for the study's use. The first and third groups of concrete beams used a volumetric replacement of fine and coarse aggregates with 5% and 10% waste tire rubber. However, steel fibers were added to the second and third groups at a rate of 1.25% of the concrete volume. Waste tire rubber and steel fibers were not replaced or added to the fourth group, the main reference group. The dimensions of each beam were 2.1×0.2×0.3 m. A concrete beam's first member is always free of external reinforcement, followed by its second member, which has one layer, and its third member, which has two layers of CFRP sheet. ABAQUS, a finite element analysis program, was used numerically to represent the third strengthening layer. The results showed that strengthening the reinforced rubberized concrete beams with a single layer of CFRP sheets increased the load at first crack and failure by 8.57% and 17.64%, respectively, compared to the unreinforced reference beam, compensating for the loss caused by the production of rubberized concrete and adding additional flexural strength. These loads increased by 31.43% and 26.45%, respectively, due to the steel fibers added to the beams containing these waste tire rubber. Strengthening with two layers of CFRP sheets increased the load at first crack and failure by 17.14 and 34.27, respectively. The steel fibers added to the beams that contained these amounts of waste tire rubber, on the other hand, caused these loads to increase by 42.86 and 49.23%, respectively. Strengthening with three layers numerically results in an exponential increase in load at the first crack and the failure by 8.03 and 52.88%, respectively. On the other hand, the loads on the beams that contained these quantities of waste tire rubber increased by 50.49% and 104.47%, respectively, when steel fibers were added to them.

Feasibility of utilising waste tyre steel fibres to develop sustainable engineered cementitious composites: Engineering properties, impact resistance and environmental assessment

This study investigates the feasibility of developing sustainable engineered cementitious composite (ECC) with polyvinyl alcohol fibre (PVAF) and recycled tyre steel fibre (RTSF) to reduce the total cost of construction materials and ease the environmental pressure for disposing of waste tyres, putting an emphasis on the engineering properties, impact resistance and environmental assessment. Experimental results reveal that partially replacing PVAF with RTSF can reduce the loss in fluidity and promote flexural performance, while the fibre bridging stress of ECC can reach up to 4.41 MPa because of the enhanced fibre bridging effect. The dynamic compressive properties of ECC present a typical strain rate effect regardless of the fibre content, and the replacement of 0.25 vol% RTSF would cause a further 5.03%–25.55% increase in total dissipation energy within the strain rates of 58.2–124.5 s−1, relative to ECC reinforced by 2.0 vol% PVAF. The synergetic effects of hybrid fibres on dynamic compressive properties of ECC can be explained by the bridging and pull-out effects of PVAF at lower strain rates, as well as the enhanced fibre-to-matrix bonding of hydrophilic RTSF at relatively higher strain rates. Upcycling of waste steel fibres in ECC holds promise as a cost-effective and eco-friendly solution for defence engineering constructions.

Prediction of the compressive strength of lightweight concrete containing industrial and waste steel fibers using a multilayer synthetic neural network

The use of waste and industrial steel fibers as part of the materials used in concrete can increase resistance and reduce cost and air pollution. It also saves energy. One of the important measures for technical inspections and assessment of the existing condition of structures, especially bridges, which is the most important communication factor, is to check the compressive strength. Considering that the calculation of compressive strength in the laboratory is done with the intervention of human power and is undoubtedly affected by human error, we decided to use it through.Predicting the mechanical properties of concrete reinforced with steel fibers based on artificial neural network models without the need to conduct any laboratory studies will save money in construction projects. Unlike classical methods in statistical theories, neural networks do not require any specific model or function along with limiting assumptions to linearize problems.For this purpose, this research was done with the aim of compensating this problem and with the aim of building a neural network with high accuracy that can make the desired predictions with the least error. In this research, this modeling was done using artificial neural networks (ANN) and Levenberg algorithm. The data used to train the neural network was collected from 45 different mixing schemes. Then the compressive strength of the sample is determined experimentally. The parameters considered for the ANN inputs are the values of steel fiber, water, water-cement ratio, cement and superlubricant. The objective data of this study included the compressive strength of each of these mixing designs at the ages of 7, 28 and 60 days. Then, to design the neural network, 75% of the data were considered as training data, 15% as target data and 15% as validation data. The compressive strength of concrete samples made from waste steel fibers increases. One of the reasons for this result is the placement and uniform distribution of fibers in the cement matrix, or in other words, the optimal amount of desired fibers in concrete. For experimental information and data, results can be seen with the help of neural network in data analysis. It was observed that the validation is correlated with a correlation coefficient above 99% and the constructed neural network has sufficient accuracy and validity.

Flexural Behavior of Reinforced Rubberized Reactive Powder Concrete Beams under Repeated Loads

Non-biodegradability of rubber tires contributes to pollution and fire hazards in the natural environment. In this study, the flexural behavior of the Rubberized Reactive Powder Concrete (RRPC) beams that contained various proportions and sizes of scrap tire rubber was investigated and compared to the flexural behavior of the regular RPC. Fresh properties, hardened properties, load-deflection relation, first crack load, ultimate load, and crack width are studied and analyzed. Mixes were made using micro steel fiber of the straight type, and they had an aspect ratio of 65. Thirteen beams were tested under two loading points (Repeated loading) with small-scale beams (1100 mm, 150 mm, 100 mm) size. The fine aggregate is replaced by 5, 10, and 15%, respectively, with crumb rubber. While replacement of silica fume was 10, 20, 30, and 50%, respectively, with very fine rubber. Also, chip rubber was added to the mixture as coarse aggregate with 5, 10, and 15%. Five tested beams were chosen as case studies to analyze and compare the results of the ABAQUS software with the experimental results. The results showed that the flexural behavior of RRPC beams that contains rubber was acceptable when compared with the flexural behavior of the RPC beam (depending on load-carrying capacity). The crack width was decreased by including waste rubber and steel fibers. There is a satisfactory agreement between the results of the numerical analysis and the results of the experimental testing. Slight ultimate load differences are targeted between the effects of the monotonic loading and the repeated loading.

Application of waste recycle tire steel fibers as a construction material in concrete

Abstract A bulk volume of waste tires, an underrated global resource, is disposed of in landfills worldwide. Extracting recycled steel fibers from these tires is an evolving trend nowadays. The outcomes of concrete having steel fibers sourced from end-of-life tires are alike industrial steel fibers. Accordingly, the attention of researchers is focused nowadays on using alternative recycled steel fibers in place of industrial steel fibers in concrete. In the current study, the review focuses on waste recycle tire steel fiber (WRTSF)-reinforced concrete applications, considering different lengths and contents for finding the research gap in this research domain. The results and methods to recycle WRTSFs in existing studies are compiled and briefed. The adoption of appropriate composition and characteristics like length, diameter, content, etc., of WRTSFs can be made by using this study to improve the mechanical properties of respective composites. Therefore, the aim of this evaluation is to encourage the application of concrete reinforced with WRTSF for different construction purposes, including but not limited to pavements, tunnel linings, bridge decks, hydraulic structures, and slope stabilization. The study seeks to provide guidance on the appropriate composition and characteristics of WRTSFs to improve the mechanical properties of the composite material.