Inclusion Of Steel Fibers Research Articles

The Effect of Nanosilica and Steel Fibers on The Mechanical Behavior of Structural Lightweight Concrete

The low strength of lightweight aggregates diminishes the strength of lightweight concrete, and the concrete's fragility impedes the ductile behavior of structures subjected to seismic stresses. The use of reinforcing materials and fibers may increase the strength of lightweight concrete by compensating for the impact of reduced strength caused by the use of lightweight particles and preventing the rapid breakdown of concrete. The performance of the materials used is an effective determinant of structural member behavior. Therefore, for computational analysis of finite elements to accurately anticipate the behavior of structural parts, precise behavioral models of materials are required. This study studied the tensile behavior of lightweight structural concrete containing steel fibers (at a volume percentage of 1%) and nanosilica reinforcing pozzolan (at a weight percentage of between 1 and 3%), using tensile strength as one of the influencing factors. together with the strain corresponding to the maximal stress. The inclusion of steel fibers and nanosilica had the largest influence on enhancing the tensile behavior of lightweight concrete, according to the data. By adding 3% nanosilica and 1% steel fibers to light concrete, the direct tensile strength has risen by 74%. In addition, the indirect tensile strength is somewhat greater in all samples than the direct tensile strength.

Effect of high temperatures on hot-bonded SCC/ECC and SCC/UHPC composite systems

The use of Engineered Cementitious Composites (ECC) and ultra-high-performance concrete (UHPC) in combination with self-consolidating concrete (SCC) in a fresh state can improve the economical and sustainability benefits of modern concretes while increasing the structural properties of SCC-elements. However, it is important to determine if the resulted hot-jointed composite systems (CS) can resist the harsh environments-like fire conditions, especially with the presence of unknown proprieties interfacial bond layer. The goal of this study is to investigate and compare the flexural and bonding behavior of the SCC/ECC and SCC/UHPC composites at ambient and high temperatures up to 800 °C. In addition to the type of modern concrete in the tensile layer, the effect of fiber reinforcement on fire endurance of CSs was also investigated through the inclusion of PVA and steel fibers in ECC and UHPC. After cooling in air, fire-exposed samples were examined for visual, microstructural, tensile, and flexural bond properties. It was confirmed that, the applied ECC and UHPFRC in CSs significantly improved the mechanical properties of SCC elements at ambient and all fire exposure temperatures. In addition to the enhanced fire endurance and better residual performance for the UHPRFC-based CSs, steel fibers were shown to be essential for the physical anchorage and bond preservation between SCC/ECC and SCC/UHPFRC, particularly at 400 °C–800 °C.

Experimental study and proposal of a design model of ultra-high performance concrete filled steel tube columns subjected to fire

To contribute a better understanding of the behaviors of ultra-high performance concrete filled steel tube (UHPCFST) under fire, fire resistance tests on twelve full-scale circular columns were performed in this study, with the emphasis on the evaluation of the effects of steel fiber content, coarse aggregate content, and load level. The failure mode, temperature distribution, axial deformation, and most importantly, the fire resistance of UHPCFST columns subject to the thermal-mechanical coupling action were analyzed. The test results showed that irrespective of the mix proportion of UHPC and the level of applied load, all the columns fail in the overall instability. Although the inclusion of steel fiber and coarse aggregate facilitates the heat transferring considerably, the temperature within the UHPC core is mostly below 400 °C during the whole heating process because of the low thermal conductivity. Moreover, as the content of steel fiber and coarse aggregate increases, better fire resistance of the UHPCFST column is generally observed, benefiting from the enhancement in global stability and the further hydration below the temperature of 400 °C. Finally, given the insufficient predictions of the fire resistance of UHPCFST columns upon the thermal parameters and the high-temperature reduction factors obtained from existing codes and research works, tailored modifications to the average temperature-based model proposed by the author previously were made. The satisfactory validation with the test results using material high-temperature reduction factors from independent research demonstrated the wide applicability of the proposed model.

Strength properties of fiber reinforced concrete including steel fibers

PurposeThis paper aims to study the influence of the presence of steel and polyolefin (PO) fibers on the mechanical and durability properties of fiber and hybrid fiber-reinforced concrete (FRC and HFRC).Design/methodology/approachHooked-end steel fibers having a length of 35 mm were applied at four different fiber content 1.0%, 1.5%, 2.0% and 2.5%, respectively. PO fibers having the length of 45 mm were also replaced with steel fibers at three different fiber content, 0.6%, 0.8% and 1.0%, to provide HFRC. The compressive, indirect tensile and flexural strengths; electrical resistivity; and water absorption were evaluated in this study.FindingsThe results showed that the addition of both steel and PO fibers led to improvements in the mechanical properties of FRC and HFRC. However, the replacement of steel fibers with PO fibers led to a slight loss in mechanical properties. Also, it was concluded that the addition of various types of fibers to concrete decreased both the electrical resistivity and water absorption compared with the control sample. Finally, distance-based approach analysis was used to select the most optimal mix designs.Originality/valueAccording to this method, the HFRC specimen including 1.2% of steel and 0.8% of PO fibers was the most optimal mix design among all fiber-reinforced mix designs.

Mechanical characterization of the concrete mixture, including steel slag aggregate and steel fibres

Steel slag is a major by-product of the steel industry, its waste management poses serious environmental threats. The slag produced by the steel industries and used as an aggregate in concrete is a sustainable key for the optimal and efficient use of natural mineral resources. In the past, numerous studies have been conducted and engineering solutions have been proposed to find the desired proportion of steel slag in concrete. The present work primarily focuses on the mechanical characterization of concrete mixes adopting Steel Slag Aggregates (SSA) as a substitution for conventional Coarse Aggregates (CA). Furthermore, an optimal concrete composition has been proposed to maximise the load-bearing strength of the concrete. First, following the standard benchmarking procedure, concrete mechanical properties are obtained. Next, the effect of replacing CA (10%, 20%, 30%, and 40%) by weight with SSA in the concrete mix is studied. The required number of cubes was cast for optimisation, and mechanical characterization (compressive, split tensile, and shear tests) was performed on the M45-grade concrete with SSA. Finally, the study has been extended with the inclusion of steel fibres in the previous optimal SSA-concrete mix. The optimum steel fibre volume fraction has been determined by performing various mechanical tests on the steel fibre concrete mix. The experimental results show that SSA can significantly improve the mechanical performance of concrete. The ideal percentage to replace CA with SSA in the concrete mixture (CM2) is 30%, which improves the concrete's compressive strength, split tensile strength, and shear strength in comparison to regular concrete. Additionally, adding steel fibres to the ideal mix (CM2) has very less impact on compressive strength but increases tensile strength and shear strength.

Quantitative damage evaluation of prestressed concrete containments with steel fiber strengthening under internal pressure

Current investigations cannot quantitatively predict the overall damage performance of prestressed concrete containment vessels (PCCVs) under internal pressure and the effect of steel fiber strengthening on the damage performance improvement has not been investigated. A new parameter definition is proposed to characterize the entire damage performance of conventional and steel fiber-reinforced concrete (SFRC) PCCVs under internal pressure in this study. The prestress loss is precisely calculated considering 40 years of the service period of PCCV. To review the possibility of operating lifetime extension of PCCV, the subsequent 60 years are also considered. Firstly, elaborate three-dimensional numerical models of conventional and SFRC containments were established. Then, three parameters to represent the extent corresponding to concrete, steel liner, and prestressed tendons of containment under damage were proposed. Finally, damage performance of conventional and SFRC containments considering the impact of prestress loss was discussed in depth. The results show that by introducing the SFRC and considering the five-year prestress loss, the pressure capacities for containment concrete, steel liner, and prestressed tendons are increased by 22.16%, 18.99%, and 12.35%, respectively. What's more, the proposed parameters can reflect the changing trend of the damage extent of containments under internal pressure and inclusion of steel fibers can improve damage performance significantly. To examine the realistic damage performance under internal pressure, the five-year prestress loss requires to be specifically considered.

Effects of steel fibers on the dynamic properties and failure process of ultra-high performance concrete

In the building area, an increasing number of applications have been made of ultra-high performance concrete (UHPC) because of its excellent properties. The steel fiber, as one of the popular admixtures of UHPC, can have a significant impact on the properties and failure process of UHPC under dynamic loading. A series of dynamic compression and Brazilian split tests were performed on UHPC specimens with six steel fiber contents based on the split Hopkinson pressure bar (SHPB) to investigate the effects of varying fiber content on the dynamic performance of UHPC. The digital image correlation (DIC) system equipped with a high-speed camera was incorporated to assist an in-depth knowledge of the UHPC failure process. Diverse experimental results were obtained and demonstrated that the presence of steel fibers can enhance the strength and toughness of UHPC, but the crack resistance of UHPC was unremarkable when the steel fiber content was 0.5%. Over the studied range, an increase in tensile strain rate of 10 s −1 resulted in a 36% growth of tensile dynamic increase factor (DIF t ) and the variation of fiber content had little effect on the growth ratio of DIF t . While with a 100 s −1 increase in compressive strain rate, the compressive dynamic increase factor (DIF c ) increased within 27% and higher fiber content decreased this value obviously. Based on the test data, logarithmic models for compressive and tensile dynamic increase factors were proposed in which the effects of strain rate and fiber content were both incorporated. DIC analysis revealed that the inclusion of steel fibers allowed for a larger peak strain of the specimen and slower macro-crack evolution after cracking. This research facilitates further understanding of the dynamic behaviors and damage mechanisms of UHPC. • The effects of steel fiber on dynamic behaviors of UHPC and corresponding mechanisms were analyzed. • DIF models incorporating the effects of strain rate and fiber content were proposed. • The crack evolution was explored in terms of strain field and the cracking speed was evaluated. • Inclusion of steel fibers allowed for greater deformation before failure and restrained the expansion of macro-cracks after failure.

Effect of silica fume on compressive strength of ultra-high-performance concrete made of calcium aluminate cement/fly ash based geopolymer

The study on geopolymers blended with silica fume is scant. This study investigates the effects of silica fume (SF) on the compressive strength of geopolymer-based ultra-high-performance concrete (G-UHPC) subject to ambient curing. Low-calcium fly ash (LCFA) and calcium aluminate cement (CAC) were activated by a combination of sodium hydroxide and sodium silicate solution to produce geopolymer binders. Effects of the CAC content, alkaline solution to binder (A/B) ratio, and sodium hydroxide (SH) concentration on the flowability and compressive strength of geopolymer binders were studied. The SF dosage varied from 5% to 30% of the total binder weight, and the Taguchi method was used to determine the optimum mix proportions. The incorporation of SF showed a complicated influence on the compressive strength, depending on the CAC content. For mixes with 20% CAC content, the compressive strength increased with increasing SF dosage. But for mixes with 10% CAC content, a high SF dosage (>10%) negatively influenced the compressive strength. The mechanisms for this contradictory behavior were discussed based on the X-ray diffraction and scanning electron microscopy analyses. The inclusion of steel fibers has a positive influence on the mechanical properties of G-UHPC. The G-UHPC mix with 1.5 vol% steel fibers achieved a compressive strength of 139.1 MPa and flexural strength of 13.5 MPa at 28 days. • Geopolymer-based UHPC was developed by incorporating calcium aluminate cement. • Taguchi analysis was used to optimise mixture compositions for geopolymer-based UHPC. • Effects of silica fume on the strength were explained via SEM and XRD analyses. • Effects of steel fiber on the mechanical properties were evaluated.

Rheological characterization of ultra-high performance concrete for 3D printing

The authors recently developed a 3D-printable ultra-high performance fiber-reinforced concrete (3DP-UHPFRC) for additive construction of structural members with significantly reduced reliance on steel bars. This study investigates the rheological behavior of the developed 3DP-UHPFRC. The effects of two major factors affecting the performance of 3DP-UHPFRC, namely steel fiber volume (0, 1%, and 2%) and nano-clay (NC) content (0, 0.1%, and 0.2% by binder mass) on workability, static yield stress, dynamic yield stress, and apparent viscosity were determined. Test results showed that the inclusion of steel fibers and NC reduced the workability and led to a significant increase in the static yield stress, dynamic yield stress, and apparent viscosity. However, the effect of NC content on the rheological properties became negligible in the mixtures made with 2% fiber content. Similarly, the effect of steel fiber volume became negligible in the mixtures made with 0.2% NC. In addition, the influence of changes in rheology due to the addition of steel fiber and NC on the extrudability and buildability of the mixtures were investigated by 3D-printing of 500 mm high hollow columns with three different print speeds. The results showed all mixtures exhibited satisfactory extrudability (i.e., no blockage of extruder or tearing of filaments was observed). In addition, the buildability of the mixtures increased as the steel fiber and NC contents increased.

Strength and Durability Studies on Steel Fiber Reinforced Ternary Blended Concrete Containing Nano Silica and Zeolite

An experimental study conducted to evaluate the hardened and durability characteristics of ternary blended concrete containing Nano-Silica and Zeolite along with steel fibers to act as micro- reinforcement has been presented in this paper. Nano-Silica and Zeolite were included in different dosages and the optimum combination of the above two materials (Nano-Silica -1% and Zeolite- 10%) has been obtained through trails from the viewpoint of workability and strength. Steel fibers have been added in varying volume fractions of 0.5%, 1.0% & 1.5%. Tests have been performed on cubes, cylinders, and prism specimens to evaluate the impact of steel fibers on various hardened and durability parameters of the ternary blended concrete. The test results clearly exhibit that inclusion of steel fibers significantly influences the material characteristics of the ternary blended concrete which includes compressive strength, indirect tensile strength, flexural strength, elasticity modulus, water absorption, Sorptivity and porosity. Nano silica and zeolite supplied the voids in the micron size of cement particle and formed a denser concrete which enhanced the improvement of the concrete. Based on the results obtained, the optimum compressive, splitting tensile, flexural strengths and modulus of elasticity of ternary blended concrete with micro reinforcement were obtained by 24.95%, 21.16%, 23.56% and 13.72%, respectively. The results suggested that cementitious materials, including ternary blended concrete with micro reinforcement, were the most influential factors on the mechanical properties.

Mechanical performance and numerical simulation of high-performance steel fiber reinforced concrete

This paper presents the outcome of the investigation of high-performance steel fiber reinforced concrete (HP-SFRC) with water to binder ratio (w:b) of 0.30- 0.40. The binder included cement replacement of 10 and 15% by silica fume. Fiber volume fractions (Vf) of 0, 0.5, 1.0 and 1.5% with aspect ratios of 80 and 53 were used. The study aims to present the effect of the inclusion of micro-silica and steel fibers on the mechanical performance of HP-SFRC. Experimental results show that moderate increase in compressive strength and significant improvement in flexural strength of HP-SFRC at Vf = 1.5% (reinforcing index = 3.88) with 15% micro-silica replacement. Empirical expressions were developed for compressive and flexural strength of HP-SFRC as a function of steel fiber volume fraction. The power relation between flexural tensile and compressive strengths was developed with an integral absolute error of 6.39. Further, the validity of the proposed models was tested against published data. A machine learning framework was established based on an adaptive neuro-fuzzy inference system (ANFIS) to predict the compressive strength of HP-SFRC mixes with higher accuracy. Finally, a multiple linear regression (MLR) model is proposed for the strength of HP-SFRC mixes and tested against published data. The validity of the MLR model is checked with experimental results and it is shown that the model has good prediction capability.

Influence of Magnetized Water on Mechanical Properties and Durability of Recycled Aggregate Concrete

The main objective of this study was to investigate the influence of using magnetized water on the mechanical properties and durability behavior in terms of freeze-thaw resistance of recycled aggregate concrete. In addition to the effect of different numbers of water rounds in the magnetic field, other variables including steel fibers, super-plasticizers and silica-fume were considered in the concrete production in order to achieve the ideal possible performance for recycled aggregate concrete made with 100% coarse aggregates replacements. For this purpose, a total of 11 concrete mixes were prepared and tested. At the first step, the effects of the mentioned variables on the basic properties, including workability, water absorption, compressive strength, splitting tensile strength, flexural strength and freeze-thaw durability test were investigated. Additionally, flexural toughness was evaluated in accordance with the post-crack strength (PCS) method and the microstructure of concrete specimens was also observed by using scanning electron microscope (SEM). The results of most experiments indicated that magnetized water, although highly effective on the mechanical properties of concrete, should not be solely utilized as a compensating factor for the defects caused by recycled coarse aggregates. The optimum toughness and durability results regarding the fiber-reinforced concrete mixes produced with recycled coarse aggregates, were related to samples containing silica-fume and 10-rounds magnetized water. Furthermore, the existence of cement replaced by 10% of silica-fume and 10-rounds magnetized water in the concrete mix MW-SF2, increased the durability of the recycled aggregate concrete by an average of approximately 63%.

ELECTRICAL RESISTANCE OF HYBRID STEEL FIBER REINFORCED SELF- COMPACTING CONCRETE

Beton yüksek basınç dayanımı yanı sıra çok düşük elektriksel iletkenliği sahiptir. Bu çalışmada kendiliğinden yerleşen betonun (KYB) elektriksel özdirenci, iletkenliği ve sıcaklık artışı üzerinde uzun ve kısa çelik liflerin etkisini, lif kombinasyonu (tek ve karma) ve kısa çelik liflerin boyuna (6 ve 13 mm) bağlı olarak belirlemek için dört adet karışım tasarlanmıştır. Bu karışımlar, lifsiz referans, sadece uzun tek lif takviyeli ve uzun lif ile iki farklı boya sahip kısa çelik lif içeren iki adet karma çelik lif takviyeli karışım olmak üzere dört farklı karışım tasarlanmıştır. Tüm çelik lif takviyeli KYB karışımları hacimce toplam %1 lif içermektedir. Karışımların belirlenmesinde EFNARC tarafından önerilen işlenebilirlik testleri (Çökme-yayılma, t500 ve J-halkası yükseklik farkı) dikkate alınmıştır. Karışımlara ait mekanik özellikler (basınç, yarmada çekme ve eğilme dayanımı) ile elektriksel özdirencin belirlenmesi için numuneler üretilmiş ve toplam 90 gün boyunca 23±2 0C’de su içerisinde kür edilmiştir. Sonuçta çelik lif takviyesinin betonun elektriksel özdirencini düşürdüğü ve dolayısıyla iletkenliğini artırdığı tespit edilmiştir. Bunun yanında karma lifli KYB numunelerinin en düşük elektriksel özdirenç ve en yüksek iletkenlik ile sıcaklık artışına sahip olduğu görülürken, narinliği yüksek olan 13 mm boyunda mikro çelik lifin betonun elektriksel özellikleri üzerinde 6 mm boyunda mikro çelik life göre daha olumlu etkiye sahip olduğu bulunmuştur.

A Review: “Experimental Study on Steel Fiber Reinforced Concrete Using flat Crimped & Round Crimped Type Steel Fiber.”

Abstract: Steel Fibre Reinforced Concretes are characterized by high tensile and flexural strengths and high ductility, as well as by a high compressive strength and a very good workability. Ductility and strength of concrete can be improved at lower fiber contents, where fibers are used in combination rather than reinforcement with a single type of fiber. Durability problems concerning one type of fiber may be offset with the presence of a second type of fiber. Steel Fiber is added by 1% volume of concrete. The different concrete mixesalong with control mix proportions as 100% round crimped type fiber, 50% round crimped type fiber -50% flat crimped type fiber and 100% flat crimped type fiber. Two types of crimped steel fiber i.e. round crimped type steel fiber and flat crimped steel fiber are used of length having 50mm. An extensive experimental investigation consisting of 12 specimen of size 50 x 10 x 10cm for determining flexural strength, 12 specimen for compressive strength and 12 specimen for split end test are used.In the experiment, an combination of steel fibre with concrete is used, which improved various mechanical properties and the strength. This review study is a trial of givingsome highlights for inclusion of steel fibers especially in terms of using them with new mix ratio combinations with concrete.

Mechanical and fractural characteristics of structural lightweight fiber reinforced concrete

AbstractRecent advances in the development of high‐performance insulating composite materials have created a new trend in the construction industry for the production of optimized lightweight structural sections. Although such sections are often found to have enhanced strength‐to‐weight ratio, their lower fracture resistance and toughness are commonly known to prone lightweight concrete sections to brittle failure with a low capacity to withstand crack propagation. To address this, in this study, six mixes containing lightweight expanded clay aggregates with a small quantity of hooked steel fibers ranging from 0 to 1.15 vol% are produced. As a result, it is found that the inclusion of steel fibers at 1.15 vol% can increase fracture energy and characteristic length by about 20 and 11 times, respectively. The result of this study is found to be significant and point to the development of highly ductile, structural‐grade lightweight fiber reinforced concrete through the use of hooked steel fibers.

Triple Blending Effect of Fly Ash, Silica Fume and Steel Fibers on Performance of High Strength Concrete

Abstract: Compressive strength is an integral property of concrete that play a key role in the construction industry. The present works investigates the effect of triple blend of fly ash, silica fume and steel fibers on the compressive, split tensile and flexural strength of concrete. Fly ash (FA) and silica fume (SF) are introduced as a partial replacement for cement for various additions of steel fibers by volume of concrete. A replacement level of 0% FA with 0 %, 5%, 10%, 15% SF in place of cement for 0% addition of steel fibers by volume of concrete is used for the preparation of first set of samples. Second set of samples were prepared with the change in fly ash proportion to 20%, keeping replacement levels of SF unchanged for 0% inclusion of steel fibers and the last set of samples were prepared with 40% FA replacement percentage without any change in the replacements of SF for the same 0% steel fibers. Likewise, the same combinations of FA and SF were repeated for 0.5% and 1% steel fibers and tested for various strength results after 28 days curing. Later, it is seen that an optimum mix of 20% FA with 10% SF for 1% inclusion of steel fibers, produced the maximum compressive strength of 81.20 N/mm2 and maximum flexural strength of 8.40 N/mm2. Keywords: Fly ash (FA), Silica Fume (SF), Steel fibers, compressive strength, flexural strength

Combined chelating and corrosion effects of steel fiber on the interfacial bond and tensile behaviors of ultra-high-performance concrete

This study evaluates the effect of corrosion on the pullout and tensile properties of ultra-high-performance concrete (UHPC) including steel fibers treated with ethylenediaminetetraacetic acid (EDTA) containing electrolyte solution for 3–9 h. For this, the steel fibers were intentionally corroded through a 3.5% sodium chloride (NaCl) solution to obtain two different corrosion degrees of 2% and 5% by weight. The roughness of the smooth steel fiber surface increases, owing to the chelating effect of the EDTA electrolyte solution, which is positive in enhancing the pullout and tensile performances of UHPC. The pullout resistance of steel fiber from UHPC increased after the treatment for up to 9 h, while the best tensile performance was obtained after 6-h treatment under non corrosive environments. The steel fibers were more severely oxidized when treated with the EDTA electrolyte solution. The pullout performance of the plain and 3-h treated steel fibers from UHPC improved for up to 2% degree of corrosion. Beyond this value, the pullout energy was deteriorated by premature ruptures. The pullout energy of steel fibers treated for 6 h or more decreased by corrosion. Under corrosive conditions, the best tensile performance was found for the steel fibers treated with the EDTA electrolyte solution for 3 h. Therefore, by considering inevitable corrosive environmental conditions, the steel fiber treated for 3 h is recommended as a suitable reinforcement for UHPC.

Coupled effect of waste tire rubber and steel fibers on the mechanical properties of concrete

Abstract Studies in the literature indicate that while tire crumb rubber can be added to concrete to replace some natural aggregates, steel fibers need to be introduced to overcome the compromise in the mechanical properties of concrete, especially compressive and tensile strength, that would be caused due to the addition of tire crumb rubber exclusively. In the present study, a minimum content of steel fibers has been added to mitigate the negative impact of addition of tire rubber fibers on the mechanical properties of concrete. The tire rubber fibers content was varied from 1% to 3% by volume whereas steel fibers were added from 0.1% to 0.3% by volume only. In this way, the effectiveness of hybridized concrete using tire rubber and steel fibers was evaluated based on its mechanical properties. The results revealed that inclusion of steel fibers overcame the reduction in strength and toughness of concrete to which tire rubber fibers have been added. Concrete with 2% tire rubber fibers and 0.2% steel fibers showed better mechanical performance in terms of compressive strength (10%), split tensile (14.7%), flexural strength (6.6%), and flexural toughness indices ( T 150 D = 46 % T_{150}^D = 46\% , f 150 D = 45 % f_{150}^D = 45\% ) as compared to the concrete with only 3% tire rubber fibers.

Characteristics of high-performance steel fiber reinforced recycled aggregate concrete utilizing mineral filler

In current state of the World, the pollution is increasing very fast. One of its major reason is the production of huge quantity of cement which causes outflow of CO2 into the environment and land dumping of construction and demolition waste which leads to the land pollution. In order to address this major issue, it is important to decrease the utilization of cement by substituting the cement with by product such as slag and using recycled aggregates as a replacement of natural aggregates. This research aimed to utilize evaluate the performance of sustainable high-performance concrete reinforced with steel fibers which is produced with recycled aggregate. Crushed stone aggregates are supplanted with recycled aggregates extracted from source concrete that had compression strength of 45 MPa and 85 MPa at proportions of 50% and 100%. Steel fibers are used at 2% to produce high-performance concrete, and in a few of the mixtures, the cement was substituted with granulated blast furnace slag. In addition to mechanical performance, the durability properties, i.e., electrical resistivity, drying shrinkage, and water absorption, of concrete blends were examined. The test outcomes show that high-performance concrete with the required characteristics can be developed utilizing recycled aggregates extracted from source concrete of high strength. The inclusion of double hooked end steel fibers considerably improves the mechanical characteristics of RAC. Concrete formed with high-quality recycled concrete aggregates and mixes comprising granulated blast furnace slag (GBFS) and double hooked end (DHE) steel fibers shows decreased drying shrinkage and water absorption in comparison to normal concrete. The outcomes of the present study assist in making of suitable high-performance concrete which is sustainable and budget friendly.

Properties of hybrid steel-basalt fiber reinforced concrete exposed to different surrounding conditions

The use of mineral basalt fibers in composites recently attracted increasing attention because of its ecological nature, availability in abundance, excellent mechanical properties, and good resistance against chemical attacks. The long-term behavior of concrete is of great importance to concrete structural integrity, especially when subjected to acid or sulfate attack. The optimization of basalt fibers and quantitative analysis in terms of fiber factor for different environmental conditions remain a research gap. In this regard, basalt fibers of various lengths and contents, together with steel fibers, were incorporated into a tailored fly ash-CaCO3 whisker mixture to produce hybrid fiber reinforced concrete (HFRC), which was then exposed to various aggressive surrounding conditions. A new fiber factor is proposed for the HFRC, and empirical models are established for the mechanical attributes. Furthermore, scanning electron microscopy (SEM) analysis of HFRC is performed to evaluate the microstructural damage caused by chemical attacks. Significant enhancement is observed in water absorption, weight loss, and compressive strength of HFRC with the inclusion of steel fibers and basalt fibers compared to plain concrete after exposure to various hazardous environmental conditions. It is found that the mineral basalt fibers presented overall worthy suitability in developing HFRC with improved properties under aggressive surrounding conditions.