Electric Arc Furnace Slag Aggregates Research Articles

Alternative Recipes SMA 11 with EAF FE-NI SLAG Aggregates the Only Possibility of Increasing the Safety and Comfort of Driving on The Highway

Objective: The objective of this study is to investigate the possibilities of using the slag of the electric arc furnace, for the development of the alternative recipe SMA 11, as one of the possibilities of increasing the safety and comfort of driving on the highway. Theoretical Framework: Theoretical, EAF (electric arc furnace slag) is an intermediate product, that during the melting process about 75% of the ore turns into slag, chemical and physical-mechanical properties of which make it a valuable aggregate for industry and especially for the development of recipes for asphalt concretes with advanced properties. The use EAF slag aggregates would be a good possibility for the development of an alternative asphalt concrete recipe for highways with comfort driving and high safety. Method: The methodology adopted for this research comprises chemical, mechanical-physical research methods, as well as the evaluation of the performance indicators of the consumable layer AC, developed according to the alternative recipe SMA 11. Results and Discussion: EAF Fe-Ni slag is classified as non-hazardous waste and has properties almost similar to conventional aggregates, and in some cases even better. The results obtained of the research have shown that the alternative recipe SMA (stone matrix aggregate) has an excellent skid coefficient, which guarantees high driving safety on the highway. Originality/Value: The use of EAF slag, in addition increasing the safety and comfort of driving on the highway, at the same time, show positive effects in terms of the rational use of natural resources, energy resources and environmental protection.

Durability of concrete mixtures containing Iranian electric arc furnace slag (EAFS) aggregates and lightweight expanded clay aggregates (LECA)

This article reports the results of an experimental investigation on novel concrete mixtures containing electric arc furnace slag aggregates (EAFS) and lightweight expanded clay aggregates (LECA), focusing on the durability properties. Six concrete mixtures consist of EAFS-natural-LECA (M-Group) and five mixtures of EAFS-LECA (N-Group) compared with 100% EAFS as reference. Workability and density of the mixtures were studied as fresh properties and compressive strength, as well as durability indexes including the electrical resistivity (RCPT and four-point Wenner test), salt-scaling under freeze and thaw cycles, abrasion resistance (abrasive groove length and wear depth), durability under wet and dry cycles, and durability factor under freeze/thaw cycles. Results showed that application of both LECA and natural aggregates, by maintaining the structural-level strength, leads to density adjustment while increasing the freeze/thaw durability factor, improving dimensional stability and controlling the level of cyclic wet/dry-stains. An average increase of durability factor of M-Group and N-Group comparing to the reference were observed up to about 124% and 63% respectively. The results indicated the positive effects of using natural aggregate and LECA on modifications of reference mixture. Measured abrasive groove length ranged between 20 and 23 mm and the depth of wear ranging from 0.1 to 0.3 mm confirming the improving effects of physical structure of EAFS aggregates. The studied mixtures, namely M6 and N5 with 0.744 kg/m2 and 1.204 kg/m2 exhibited the lowest salt-scaling mass-loss with 31% and 112% increase compared with the reference.

Design Procedures for Sustainable Structural Concretes Using Wastes and Industrial By-Products

The protection of the environment must be a priority in our society, and the construction sector can contribute significantly to this goal. Construction, being one of the industrial sectors that is more demanding in terms of raw materials, must reinforce its effort to implement, in a more profound and systematic way, the paradigm of the circular economy. In this sense, in recent years several studies have been trying to contribute solutions aimed at reintroducing industrial by-products or residues in new products for the construction industry. It should be noted that nowadays it is increasingly important to introduce a higher percentage of recycled materials in concrete. In this context, the present work addresses the appropriateness of a design procedure proposed to maximize the content of electric arc furnace slag (EAFS) and include recycled tire steel fibers (RTSF) in the production of more sustainable structural concretes. For this, the properties of various concrete mixtures at the fresh and hardened state, obtained by the substantial substitution of coarse and fine natural aggregates by EAFS and fly ash (FA), were investigated. The design of EAFS mixtures was based on two conventional reference mixtures (REF1 and REF2), and by using the modified Andreasen and Andersen particle packing model, these were optimized to achieve maximum packing density. Compressive strength, modulus of elasticity behavior, and fresh and physical properties were assessed in order to define the best mix proportions with respect to the predefined requirements of ordinary mixtures. Untreated recycled tire steel fibers (RTSF) were included in the developed sustainable concrete to perform a comparison of the physical properties with unreinforced concretes developed with natural aggregates (REF2) and with EAFS aggregates (EAFS8D1). This incorporation was intended to improve the physical behavior of unreinforced concretes with EAFS aggregates. Mixtures with high percentages of waste aggregates up to 70% (in weight), and 10% (in weight) of FA were obtained, showing competitive mechanical behavior compared to REF1 and REF2. These concrete compositions showed minimum and maximum compressive strengths between 9 MPa and 37 MPa, respectively. This study coverd the two major classes of concrete used as structural material, namely structural concrete and fiber reinforced concrete.

Effect of electric arc furnace slag and magnetite materials on EMI shielding properties of cementitious composites

To impart electromagnetic interference (EMI) shielding in cementitious composites, electrically conductive and electromagnetic absorbing additives are generally used. This research examined the effect of adding electric arc furnace slag (EAFS) or heavyweight aggregates (HWA), alone and in combination with carbon fibre (CF), on the EMI shielding properties of cementitious composites. Different percentages of both additives were added to a control mix to study the effect on mechanical properties, electrical conductivity and EMI shielding. Optimal shielding was produced for aggregate contents of 1.5 wt%, with values of 5.18 dB for the EAFS mixes and 3.25 dB for the HWA mixes, within the frequency range 30 MHz to 1.5 GHz. Hybrid mixes were fabricated using 0.7 wt% of 12 mm long CF and three different percentages of each aggregate. In combination with the CF, the optimal level of shielding was produced with EAFS and HWA contents of 1 wt%. These optimal shielding levels were 34.21 dB and 36.78 dB, respectively, within the 30 MHz to 1.5 GHz frequency range. A further increase in either type of aggregate produced a gradual reduction in EMI shielding effectiveness.

Seismic reliability of RC frames casted with EAF concretes

The use of recycled aggregates is one way to fulfill sustainability goals in concrete industry, and among others, Electric Arc Furnace (EAF) slag aggregates has been proven to be promising. Past research demonstrated a significant increase of mechanical properties of EAF concretes when compared with ones made with natural aggregates (NA); however, at the same time, their use implies also an increase of self-weight loads. The present study aims therefore to investigate the seismic reliability of reinforced concrete frame buildings made with EAF, and compare it with the same structural configurations built with NA mixes, in order to show how the change in mechanical properties and self-weight can impact the seismic response of the analyzed case-studies.

Microstructural analysis of siderurgical aggregate concrete reinforced with fibers

The development of cracks in concrete structures is one of the significant issues with maintaining high strength after hardening. One way to prevent and control this problem is to use fibers. This paper investigates concrete containing electric arc furnace slag aggregates reinforced with fibers. The fibers used in this study are steel fibers and three kinds of polypropylene fibers; polyolefin fibers (modified polypropylene), polypropylene homopolymer, and high-toughness polypropylene. By checking the compressive and flexural strength of concretes made with fibers, it can be seen that the best results at 28 days are found for concrete with steel fibers, namely 62 MPa with 0.9% of fibers. On the contrary, the lowest values are for concrete containing polyolefin fibers, 51 MPa, and the same percentage of fibers. Additionally, under flexural strength testing, at the age of 28 days, the strength of these samples with 0.9% of fibers was 9.54 MPa, a value that is comparable to test concrete with the same percentage of steel fibers, 10.67 MPa, despite the low workability of concrete containing polyolefin fibers with a slump of 25 mm. Moreover, the boundary transition area analysis shows that the excellent connection between the fibers and cement paste near the siderurgical aggregate has caused no cracks in this area. In contrast, cracks can be observed in critical areas near the natural aggregates.

Durability of high-performance self-compacted concrete using electric arc furnace slag aggregate and cupola slag powder

The current trend in the development of self-compacting concrete with sustainable construction materials has served as a guide to design a novel self-compacting concrete, with siderurgical by-products (steel slag aggregates and cupola slag powder as supplementary cementing material) that also meets the demands of high-performance concrete. This research sets out to clarify the unknown behavior of slag concrete, its durability, which is the ability to withstand any process that tends to deteriorate it. In order to assess the durability of this eco-friendly concrete, three control mixes were manufactured with the same high-quality coarse aggregate (diabase) and three different fines, limestone filler, fly ash and cupola slag powder. All the mixtures were subjected to the same tests, the results demonstrate that steel slag concrete shows an excellent response against carbonation, a slightly lower response against thermal shock cycles, similar drying shrinkage and a superior response against the action of freezing-thawing cycles and abrasion wear in comparison to the control mixes.

Utilization of Industrial Byproducts for Enhancing the Properties of Cement Mortars at Elevated Temperatures

The research on industrial byproducts, such as slags and fly ash, was intense during the last decades in the building sector. Apart from the environmental benefits coming from their exploitation, their application may lead to the production of cost effective and durable building materials, such as mortars and concrete. The impact of industrial byproducts on the resistance of materials to fire and elevated temperatures was assessed by many scientists, however, it is still an open field of research. In this study, locally available byproducts were investigated, including High Calcium Fly Ash (HCFA), coming from lignite-fired power plants, as well as Ladle Furnace Steel (LFS) slag and Electric Arc Furnace (EAF) slag aggregates, originating from the steel making industry. Six mortar compositions were manufactured with substitution of Ordinary Portland Cement (OPC) with HCFA and LFS slag (20% w/w) and of natural aggregates with EAF slag (50% w/w). At the age of 7, 28, and 90 days, the physico-mechanical properties of the specimens were recorded, while they were further exposed at elevated temperatures, concerning 200 °C, 400 °C, 600 °C, 800 °C, and 1000 °C. After each exposure, their physico-mechanical and microstructure characteristics were identified. From the evaluation of the results, it was asserted that HCFA and EAF slag aggregates enhanced the overall performance of mortars, especially up to 600 °C. LFS was beneficial only in combination with EAF slag aggregates.

An alternative experimental methodology to determine the diagonal cracking resistance of steel-reinforced concrete beams

An alternative experimental method for predicting the diagonal shear cracking resistance of steel-reinforced concrete beams is developed in this paper. Conventional extensometric strain-gauge rosettes are placed on the lateral surfaces of a set of four beams. As diagonal cracking propagates through the beams, the load–strain curves flatten out at a plateau and the mechanical property under consideration may be determined. The method is applied to four beams cast from pumpable and self-compacting concrete mixes with cement types I and IV containing electric arc furnace slag aggregates. The feasibility of applying standard design code formulas to the concretes containing these aggregates may therefore be studied and compared with other recent research works. Accurate experimental results were obtained with this method without having to interrupt the test for subjective visual appraisals of the test specimen.

Investigation on the sustainable use of electric arc furnace slag aggregates in eco-friendly alkali-activated low fineness slag concrete as a green construction composite

The construction industry uses a high amount of energy in various forms. The main energy-consuming processes in this industry are ordinary Portland cement (OPC) production and aggregate crushing. The high energy consumption level can be interpreted as a high amount of CO2 and other greenhouse gas emissions. There are different approaches to reduce these harmful impacts, such as using alkali-activated slag concrete (AASC) and incorporating recycled and by-product aggregates like Electric arc furnace (EAF) slag. Also, using low Blaine fineness (lower than 3000 cm2/g) ground granulated blast furnace slag (GGBFS) in AASC can lead to lower energy consumption.In this research, EAF slag (EAFS) aggregates were considered as substitution of natural aggregates in AASC with low Blaine fineness GGBFS (about 2700 cm2/g) for the first time. Different mechanical and durability tests such as compressive strength, tensile strength, modulus of rupture, water absorption, water penetration, RCPT, and oxygen penetration in addition to XRD, SEM, and EDX were carried out to evaluate the properties of AASC with EAF aggregates. Also, the CO2 emissions due to the production of concrete with the mix designs were calculated.The results indicated that AASC containing low Blaine fineness GGBFS had an outstanding performance in terms of mechanical properties. Replacing coarse natural aggregates with EAFS in AASC resulted in no significant decrease in mechanical properties. However, using EAFS fine aggregates caused a decrease in mechanical properties. AASC with low Blaine fineness GGBFS showed inferior yet acceptable durability properties compared to OPCC. Overall, an eco-friendly, recycled concrete is proposed with low energy consumption and low emission of CO2 (about 50% reduction) and lower cost (about 30%), compared to OPCC.

Cohesive zone modeling of EAF slag-included asphalt mixtures in fracture modes I and II

Fracture properties of asphalt mixtures containing fine and coarse Electric-Arc Furnace (EAF) aggregates were determined at low-temperature conditions by implementing Cohesive Zone Modeling (CZM). Semi-Circular Bending (SCB) test was conducted in both fracture Mode I and II (opening tensile and in-plane shear, respectively), and the bi-linear traction separation law was used to obtain the coefficients of cohesive elements. To determine the fracture failure probability concerning the adopted testing parameters, the two-parameter Weibull distribution curve was fitted on the FEM results. Based on CZM simulation modeling, it was observed that the simulated curves were promisingly consistent with the experimental results. Weibull distribution analysis revealed that the inclusion of fine EAF slag aggregates increases the fracture failure probability compared with those containing coarse aggregates. A statistically predictive model was introduced, based on the Weibull distribution results, to predict the in-plane shear (Mode II) fracture properties using those of Mode I.

Durability of steel fiber reinforced concrete with coarse steel slag aggregates including performance at elevated temperatures

The present study investigates the performance of concrete with Electric Arc Furnace (EAF) steel slag as coarse aggregate and steel fiber reinforcement. EAF slag was tested for suitability as concrete aggregate regarding chemical properties, granulometry, apparent specific density, water absorption and flakiness index. Test concrete mixtures were prepared with EAF slag as coarse aggregate with either no reinforcement, or with 30 mm or 60 mm steel fibers at a volume ratio of 0.7%. The test concretes were compared to reference concretes with natural limestone coarse aggregates to determine potential improvement due to the use of EAF slag or due to the use of different steel fiber sizes. The testing program consisted of measuring fresh concrete properties, as well as mechanical properties and toughness of the hardened concrete. The results on fresh concrete showed that water absorption of EAF slag needs to be considered at the design stage, otherwise there is a workability loss in fresh concrete, and that EAF slag use leads to considerable increase in density. However, the mechanical properties of concrete with EAF slag aggregates were significantly higher compared to the reference concrete. This increase was also recorded regarding the toughness and impact resistance of Steel Fiber Reinforced Concrete (SFRC). Durability measurements regarding drying shrinkage, abrasion resistance and freeze-thaw resistance showed that the use of EAF slag as coarse aggregate improved the performance of SFRC. Regarding thermal behavior, the thermal conductivity of the test concretes was measured, while hardened SFRC specimens were subjected to elevated temperatures up to 870 °C. After heating, the microstructure of the concrete was investigated, and the specimens were tested for compressive strength and ultrasonic pulse velocity. The results show that although EAF slag aggregates tend to form micro cracks at temperatures higher than 600 °C and the rate of strength loss is increased, there is a reduced risk of spalling.

Phosphorus removal from wastewater using electric arc furnace slag aggregate

ABSTRACT Electric arc furnace (EAF) slag aggregate, a waste by-product of the steel industry, exhibited a high potential for phosphorus (P) removal and had attracted considerable attention. The main objectives of this study were to evaluate the performance of using EAF slag aggregate as an adsorbent for P removal and identify its P removal capacity. A series of batch tests showed that P removal capacity of EAF slag increases gradually with the increase of pH with a range of 2–10, while the highest P removal capacity (1.94 mg/g) can be obtained at pH 12. The adsorption kinetics of P on EAF slag can be described by pseudo-second-order kinetic equations. Isothermal adsorption simulations showed that the best fitted model was the Freundlich model with a correlation coefficient of 0.9825. A continuous flow column experiment feeding a synthetic influent containing 15 mg P/L was operated for 60 days and the P removal efficiency was greater than 95% with a P removal capacity of 1.6 mg P/g slag. The results obtained in this study showed that EAF slag could act as an efficient adsorbent for P removal. Calcium phosphate precipitation depends on the release of Ca2+ and OH− by the dissolution of calcium oxide in EAF slag was found to be the dominant removal mechanism for P removal.

Influence of elevated temperature on properties of radiation shielding concrete with electric arc furnace slag as coarse aggregate

The development of value-added materials from by-product of the steel-making process can promote sustainability in construction to move towards a circular economy. The use of Electric Arc Furnace (EAF) steel slag as heavyweight coarse aggregate to develop sustainable radiation shielding concrete could provide both technical and economic benefits with less environmental impact. This contribution investigates the behaviour at high temperature of a sustainable radiation shielding concrete. Thermal behaviour of EAF slag concrete was compared to another heavyweight concrete made of barite aggregates and to a normal-weight concrete. On one hand, the thermal stability of the three different aggregates was determined via simultaneous Thermogravimetry and Differential Scanning Calorimetry analyses and visual observations after 10 °C/min heating. On the other hand, the evolution of thermal conductivity of concretes during heating, the residual mechanical properties and the assessment of potential spalling occurrence were investigated. Stereo-microscope and Scanning Electron Microscope pictures provide additional explanations by showing the paste-aggregate interface after heating at 450 °C. The results indicated that EAF concrete displayed less strength reduction at increasing temperature. This improved behaviour is attributed to both the strong bond between the paste and the aggregates, and the better thermal behaviour of the EAF slag aggregates compared to barite aggregates.

Bond performance of reinforced concrete beams with electric arc furnace slag aggregates

The present study was conducted to evaluate the bonding performance of reinforced concrete beams with electric arc furnace oxidizing slag aggregates. The specimens were tested by varying the aggregates, and the top and bottom longitudinal reinforcement position, depending on concrete placement. The specimens containing electric arc furnace oxidizing slag aggregates showed bond performance that was on average of about 8% to 20% higher than that of the specimens using natural aggregates. The bond strength was higher at the corner longitudinal reinforcement than at the inner longitudinal reinforcement and higher at the bottom reinforcement than at the top reinforcement, regardless of the aggregate type. The experimental results were consistent with results from previous studies with concrete containing natural aggregates. Comparison with previous studies confirmed the excellent bond performance of the concrete with electric arc furnace oxidizing slag aggregates, and demonstrated the use of concrete containing electric arc furnace oxidizing slag aggregates for structural members.

High Performance Self-Compacting Concrete with Electric Arc Furnace Slag Aggregate and Cupola Slag Powder

The development of self-compacting concretes with electric arc furnace slags is a novelty in the field of materials and the production of high-performance concretes with these characteristics is a further achievement. To obtain these high-strength, low-permeability concretes, steel slag aggregates and cupola slag powder are used. To prove the effectiveness of these concretes, they are compared with control concretes that use diabase aggregates, fly ash, and limestone supplementary cementitious materials (SCMs, also called fillers) and intermediate mix proportions. The high density SCMs give the fresh concrete self-compacting thixotropy using high-density aggregates with no segregation. Moreover, the temporal evolution of the mechanical properties of mortars and concretes shows pozzolanic reactions for the cupola slag. The fulfillment of the demands in terms of stability, flowability, and mechanical properties required for this type of concrete, and the savings of natural resources derived from the valorization of waste, make these sustainable concretes a viable option for countless applications in civil engineering.

Experimental studies on shear strength characteristics of alkali activated slag concrete mixes

In the present study an attempt has made to study the shear strength characteristics of alkali activated slag concrete mixes developed using steel slag sand and Electric Arc Furnace (EAF) slag aggregates, respectively, as the fine and coarse aggregates. These mixes use the ground granulated blast furnace slag (GGBFS) as the primary source material. Thus it is to be recognized that all the three materials used – GGBFS, slag sand and EAF slag aggregates are by-products of the Iron and Steel Industry, and are available in very large quantities demanding safe disposal. Different amounts of Sodium silicate solutions, with specified amounts of Sodium hydroxide flakes dissolved in them, are used as alkaline solutions. The test results indicate higher compressive strengths values for all the mixes in the range of 50–70 MPa with their shear strength values ranging between 7.5 and 12.0 MPa. Further the relationship between shear strength and compressive strength of the AASC mixes was also developed.

The study of properties and behavior of self compacting concrete containing Electric Arc Furnace Slag (EAFS) as aggregate

Electric Arc Furnace Slag (EAFS) can be efficiently reused as aggregate in the production of high-volume batches of hydraulic concrete mixes that show interesting properties in both the fresh and the hardened state. Mixtures containing EAFS aggregate in proportions of nearly 50% by volume are prepared for use as pumpable and self-compacting mixes with consistency classes of S4 and SF2, respectively. Characterization of the mixtures is presented, examining practical aspects such as thixotropy, segregation in the fresh state (under 6%), and mechanical and microstructural evolution in the hardened state. The results yielded compressive strengths of approximately 60 MPa and elastic moduli of 38 GPa after one year. Finally, real-scale flexural elements are cast and subjected to sustained loading tests of moderate intensity. Long-term deflection values were approximately 50% (pumpable mixes) and less than 40% (self-compacting mixes) of the maximum admissible values specified in current standards.

High Strength Flowable Alkali Activated Slag Concrete Mixes produced using industrial wastes

A new class of High–Strength Flow ableAlkali activated Slag Concrete(HSFASC)mixes is developed using steel slag sand and EAF (Electric Arc Furnace) slag aggregates, respectively, as the fine and coarse aggregates. These mixes use the ground granulated blast furnace slag as the source material. Thus it is to be recognized that all the three materials used – GGBFS, slag sand and EAF slag aggregates are by-products of the Iron and Steel Industry, and are available in very large quantities demanding safe disposal. Different amounts of Sodium silicate solutions, with specified amounts of Sodium Hydroxide flakes dissolved in them, are used as alkaline solutions. Test specimens were cast using a total of nine HSFASC mixes, (based on Taguchi’s Method), each of which satisfied the relevant EFNARC guidelines with respect to their rheological properties. The test results indicate higher compressive strengths values for all the mixes tested herein. Microstructure studies are conducted on samples from the fractured surfaces of test specimens of different mixes, using advanced SEM, EDX and XRD analyses and the results are discussed.

Effect of addition of OPC on Performance characteristics of Self-compacting Alkali activated slag concrete mixes

An attempt has been made in the present research to develop construction friendly, self-compacting, alkali-activated slag concrete mixes with ground granulated blast furnace slag (GGBFS) as the major source of binder material. In an effort to make the concrete mixes more eco-friendly and sustainable, by-products from Iron and Steel Industry such as steel slag sand and Electric Arc Furnace (EAF) slag aggregates, were used as the fine and coarse aggregates respectively. While the total binder content has been varied in the range of 700 – 800 kg/m3 (in increments of 50 kg/m3), all the trial mixes had a constant w/b ratio of 0.40. Different amounts of sodium silicate solutions, with specified amounts of sodium hydroxide flakes dissolved in them, are used as alkaline solutions, with the combined Na2O percentage in them varying between 6% - 8%. Test specimens were cast with mixes which showed enhanced flow-properties as per relevant EFNARC guidelines and were tested for their mechanical strength and durability characteristics. Effect of admixing of ordinary Portland cement (OPC) in smaller percentages (2.5% - 10 %, in increments of 2.5%), on the performance characteristics of this novel class of AAC mixes is evaluated. Increased cement contents are found to lead to better flow ability properties and higher strengths values with lower sorptivity values in all the Cement-Admixed, Self-compacting, Alkali-Activated Slag Concrete mixes (CASAASC mixes) tested herein. Studies with a scanning electron microscope have shown more densified morphologies developed, accounting for better performances of these mixes.