Electric Arc Furnace Slag Aggregates Research Articles

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.

Seismic reliability assessment of code-conforming reinforced concrete buildings made with electric arc furnace slag aggregates

Recent studies have demonstrated how Electric Arc Furnace (EAF) concrete represents a sustainable alternative to ordinary concretes, and that it could be satisfactorily employed to realize reinforced concrete (RC) elements. However, a comprehensive study about the effects of its use in RC structural systems, both in terms of structural safety under static and dynamic loads, and environmental impacts along the whole life cycle, has not been investigated yet. This work analyzes the seismic reliability of standard residential buildings (cast in place RC frames), considering three different configurations (3-, 6- and 9- story building type) designed considering ordinary concretes made with natural aggregates (NA) according to the novel Italian seismic code, which is similar to the Eurocode 8 approach. Non-linear time history analyses have been carried out to investigate the seismic response of the analyzed cases comparing results obtained from the benchmark structures (i.e. the NA ones) with those coming from the same made with EAF mixes, in order to verify the suitability in using sustainable EAF concrete mixes in seismic areas. Lastly, a seismic reliability analysis has been carried out for comparative purposes, demonstrating how EAF concrete overstrength compensates for the extra efforts that the analyzed RC frames may undergo during seismic events.

Durability of concrete with electric arc furnace slag aggregate

The durability of concrete mixes with EAF slag as aggregate (HS) is studied; mixes with limestone (HC) and barite (HAB) aggregates were used as reference for structural and heavy-weight applications, respectively. Compressive strength, elastic modulus, water penetration under pressure, wet-dry cycles, freeze-thaw cycles, influence of environmental condition and leaching tests were conducted. The results indicate that HS tends to present higher depth of water penetration under pressure, a slightly higher expansion, higher carbonation depth and similar compressive strength than reference HC. Should be payed attention to the formation of stain points on HS concrete surface subjected to wet-drying cycles.

Structural reliability of bridges realized with reinforced concretes containing electric arc furnace slag aggregates

The development of sustainable concretes is becoming an emerging issue in civil construction sector. The use of recycled aggregates is one way to fulfill sustainability goals in concrete industry, and among others, the use of Electric Arc Furnace (EAF) slag aggregates has been proven to be promising in the construction of sustainable reinforced concrete structures. 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 contribution aims to investigate the reliability of structural systems realized with EAF concretes, with special emphasis to bridge structures. A wide dataset of 172 experimental tests for mechanical characterization of EAF concretes is built up and subsequently used to analyze the increment in concrete compressive strength and self-weight loads for three different EAF concrete classes (i.e. C1, C2, A). Two different bridge types, considered as case-study examples, are designed considering ordinary concrete mixes, and subsequently, a reliability analysis is run for each EAF concrete class in order to investigate the variation of structural safety margins related to the use of the sustainable EAF concretes in replacement to the ordinary NA concrete mix. Results show how structural safety of the analyzed bridges built up with sustainable EAF concretes is characterized by similar levels of structural reliability, in particular evidencing higher values for EAF concrete classes C1 and C2 with respect to those computed for NA concretes.

Compressive strength and durability properties of roller-compacted concrete pavement containing electric arc furnace slag aggregate and fly ash

This study investigates the effects of electric arc furnace (EAF) slag aggregate and fly ash on compressive strength and durability properties (i.e. water absorption, abrasion resistance, and sulfate resistance) of roller-compacted concrete pavement (RCCP). The EAF slag aggregate as natural aggregate substitution was used at three levels (i.e. 0%, 50%, and 100%) and cement was replaced by fly ash at three ratios (i.e. 0%, 20%, and 40%). The EAF slag aggregate used in this study was exposed to outdoor condition for several months to reduce the volume instability. The RCCP mixing proportions were determined by soil compaction method. The compressive strength of RCCP was examined at 3-, 7-, 28-, and 91-day age. Meanwhile, the water absorption, abrasion resistance, and sulfate resistance of RCCP at 91-day age were used to study the durability properties. Furthermore, the length change of mortar bars made with EAF slag aggregate was measured to evaluate the expansive potential of EAF slag caused by autoclave condition and alkali-silica reaction (ASR) condition. Additionally, X-ray diffraction analysis was offered to identify the crystalline phases of mortar patterns under autoclave and ASR testing condition. The results presented that the compressive strength and sulfate resistance of RCCP containing EAF slag aggregate declined slightly, whereas the water absorption and abrasion resistance increased in comparison to those of traditional RCCP. Besides, the use of fly ash as cement substitution improved the compressive strength of slag-RCCP at long-term age. A replacement of 20% fly ash provided the slag-RCCP fulfilling the strength and durability requirements for pavement. In addition, the expansion in terms of length change of mortar bars indicated that EAF slag aggregate after the proper treatment performed the volume stability under the autoclave condition and ASR test.

EAF Slag Aggregate in Roller-Compacted Concrete Pavement: Effects of Delay in Compaction

This study investigates the effect of delay in compaction on the optimum moisture content and the mechanical propertie s (i.e., compressive strength, ultrasonic pulse velocity, splitting tensile strength, and modulus of elasticity) of roller-compacted concrete pavement (RCCP) made of electric arc furnace (EAF) slag aggregate. EAF slag with size in the range of 4.75–19 mm was used to replace natural coarse aggregate in RCCP mixtures. A new mixing method was proposed for RCCP using EAF slag aggregate. The optimum moisture content of RCCP mixtures in this study was determined by a soil compaction method. The Proctor test assessed the optimum moisture content of mixtures at various time after mixing completion (i.e., 0, 15, 30, 60, and 90 min). Then, the effect of delay in compaction on the mechanical properties of RCCP mixtures at 28 days of age containing EAF slag aggregate was studied. The results presented that the negative effect on water content in the mixture caused by the higher water absorption characteristic of EAF slag was mitigated by the new mixing method. The optimum water content and maximum dry density of RCCP experience almost no effect from the delay in compaction. The compressive strength and splitting tensile strength of RCCP using EAF slag aggregate fulfilled the strength requirements for pavement with 90 min of delay in compaction.

Radiation shielding and mechanical properties of steel fiber reinforced concrete (SFRC) produced with EAF slag aggregates

In this paper, the influence of Electric Arc Furnace (EAF) slag aggregates on the mechanical and gamma ray shielding properties of concrete mixtures were studied experimentally. EAF slag and crushed limestone were used as aggregates while steel fibers of different geometry were also incorporated into the concrete mixtures. Unit weight, ultrasonic pulse velocity, compressive strength, split tensile strength, flexural toughness and shielding properties in gamma energies 244, 344, 779, 964, 1112 and 1408 keV were measured and compared to the corresponding values of conventional concrete. The use of EAF slag aggregates results in the production of higher density concrete compared to conventional concrete with limestone aggregates with enhanced mechanical and shielding properties and adequate workability. Additionally, the inclusion of fibers improves the flexural behavior of concrete and slightly increases compressive strength and unit weight.

Experimental and numerical investigation on the cyclic behavior of RC beam column joints with EAF slag concrete

An experimental and numerical study about exterior reinforced beam-column joints made with recycled concrete containing Electric Arc Furnace (EAF) slag aggregate, and subject to horizontal reversed cyclic loading, is shown in this paper. Three real scale joints were tested under quasi-static cyclic loading, to study the influence of EAF concrete use on the global behavior of the specimens, in terms of ultimate load, hysteresis response and dissipated energy. The joints exhibited the same failure mode, which involved the shear failure of panel joint and yielding of beam steel longitudinal bars. Then a numerical investigation was carried out, consisting of three-dimensional non-linear finite-element (FE) models, which were validated with the experimental results. Lastly, a parametric study was carried out to understand the effects of column axial load, beam longitudinal reinforcement bar amount and column transverse reinforcement ratio. Results indicate that, in all the analyzed cases, the seismic performance of the joints made with EAF slag concrete is better than with conventional material.

Roller-compacted concrete pavement made of Electric Arc Furnace slag aggregate: Mix design and mechanical properties

This research investigates the feasibility of using Electric Arc Furnace (EAF) slag aggregate and fly ash in Roller-compacted concrete pavement (RCCP). After treatment process, EAF slag aggregate was examined the potential expansion caused by hydration reactions and alkali-silica reactions. The test results showed that EAF slag aggregate is stable the volume and can be used in concrete. In the RCCP mixtures, EAF slag was used as a substitute for natural coarse aggregates with three percentages (i.e. 0%, 50% and 100%) and cement was partially replaced by fly ash at three content levels (i.e. 0%, 20% and 40%). The optimum moisture content of RCCP mixtures containing EAF slag aggregate and fly ash were determined by the soil compaction method. The unit weight and mechanical properties (i.e. compressive strength, splitting tensile strength and elastic modulus) of RCCP were examined through testing program. As a result, the fresh and hardened unit weight are similar to those of conventional RCCP. Moreover, the compressive strength, splitting tensile strength and elastic modulus of RCCP decreased with increasing EAF slag aggregate ratio at all ages. Nevertheless, the conjunction of EAF slag aggregate and 20% fly ash in the RCCP mixtures improved the mechanical properties in the long-term ages. This study has proved that the RCCP containing EAF slag aggregate and fly ash can be employed to develop pavements as an exposed wearing surface. In addition, a predicting model was proposed to calculate compressive strength of RCCP.

Life Cycle Assessment of Concrete Products for Special Applications Containing EAF Slag

Electric Arc Furnace (EAF) slags are steel slags that derive from the steel manufacturing process and are produced in large volumes (∼10% of the steel produced) worldwide, which pose an environmental threat when disposed in landfills. Their physicochemical characteristics (high density, roughness and resistance to fragmentation) favor their use in concrete products for special applications, especially where high resistance to abrasion is required and the increase concrete density is not a problem. The special concrete applications considered in this paper were industrial pavements, heavyweight concrete and pervious concrete paving blocks and all proposed products were designed in order to perform in a similar way as reference products with ordinary concrete. Then, in order to quantify the benefits arising from the utilization of an –otherwise useless– industrial by-product, a Life Cycle Assessment was carried out for each of the concrete products. One m3 or one m2 of concrete was selected as functional unit and a cradle-to-gate approach was followed for the LCA, including material extraction, transport and production and placement, stating the limitations and system boundaries used. Cost estimation for each of the products was also performed in order to assess their commercial viability. The results show that for industrial pavement construction, concrete with EAF slag aggregates has similar environmental load and cost with the reference concrete, while in the case of pervious paving blocks the use of EAF slag aggregates reduces the environmental load by 14% at a reduced cost, and for heavyweight concrete the environmental load is reduced by 44% at a significantly lower cost.

Comparative analysis of the transmission factors of lead and concrete manufactured with electric arc furnace slag aggregates

The most common form of shielding utilized is lead in X-ray rooms, and little attention is given to alternative and more sustainable types of shielding materials. This work evaluates the X-ray radiation shielding parameters of concrete made with fine and coarse electric arc furnace slag aggregates and compares the transmission factor of this type of concrete with lead. Different thicknesses of concrete specimens of 15cm, 17cm, 19cm and 22cm were exposed to X-ray energies of 40kV, 60kV, 80kV, 100kV, 125kV and 150kV. In this work, it was found that at increased thicknesses of the concrete samples, the linear attenuation, mass attenuation coefficient, half value layer and tenth value layer of the concrete improved. It was found that it is possible to construct slag concrete shielding partitions with thicknesses of 104.5mm, 156mm and 176mm respectively which give the same transmission factor as the lead thickness usually used. At 125kV, a relation has been created showing that there was good correlation between the theoretical and experimental values of the transmission factors at the different thicknesses of the slag concrete which could be used to design the X-ray partitions walls.

Electric arc furnace slags in cement-treated materials for road construction: Mechanical and durability properties

Electric arc furnace (EAF) slags are by-products of a widespread steelmaking process. The recycling of these materials as artificial aggregates in different road applications is a well established practice, which has allowed to reduce the consumption of natural resources and to minimize waste production and costs of landfilling. However, these aggregates are still underutilized in cement-treated materials (CTMs), which consist of mixtures of aggregates blended with small amounts of cement and water that harden after compaction to form a strong paving material. In the light of these considerations, different cement-treated materials, each containing different percentages of natural and artificial aggregates were analyzed. After a preliminary characterization of chemical, physical and durability properties of EAF slag aggregates, a mix design procedure based on both moisture-density approach (gyratory compactor) and mechanical testing (unconfined compression test and indirect tensile test) was performed to identify the optimum cement and water content of CTMs. The design mixtures were then subjected to 5 different accelerated aging procedures in order to study the influence of some factors (temperature, pressure and humidity) on the durability of the cement-treated materials. The results highlighted how the EAF slags represent suitable aggregates for cement-treated materials. The use of these aggregates produced a greater compaction difficulty, but guaranteed excellent mechanical performances, above all in terms of indirect tensile strength. The durability analysis demonstrated that the recycled mixtures showed a worse behavior than the reference one, composed only by limestone aggregates. However, if correctly designed, balancing the percentage of natural aggregate replacement, these mixtures could represent suitable and durable solution for base and sub-base pavement layers.

Properties of pervious concrete made with air-cooling electric arc furnace slag as aggregates

In this paper, properties of pervious concrete made with air-cooling electric arc furnace slag (EAFS) as aggregates are investigated. Test results showed that under the same condition, pervious concrete made with EAFS aggregates had a better mechanical strength and a greater permeability coefficient than that made with natural river gravels. In addition, pervious concrete made with EAFS aggregates had a lower weight loss than that made with natural river gravels for the soundness tests. The dimension stability test showed that the possible expansion characteristic of EAFS became not so significant for pervious concrete due to the voids inside the system. It is concluded that pervious concrete made with EAFS aggregates is a good alternative in many ways.

Radiation shielding properties of concrete with electric arc furnace slag aggregates and steel shots

Heavyweight concrete, prepared with a mixture of concrete and heavyweight aggregates or metallic components, is generally used for radiation shielding purposes. In the present study the radiation shielding properties of concrete prepared with electric arc furnace slag aggregates (EAFSAs) and steel shots, was investigated. The results indicated that concrete mixed with 50% EAFSA and 50% steel shots meets the weight and radiation requirements. The use of 50% EAFSA results in a decrease in the cost of concrete and also conserves a useful material, such as iron ore.

Properties of concretes with Black/Oxidizing Electric Arc Furnace slag aggregate

Abstract The aim of this work is to comprehensively investigate the possibility of partially substituting natural aggregates with Black/Oxidizing Electric Arc Furnace (EAF) slag in concrete production. Five recycled and one traditional mixes were produced to identify a convenient substitution ratio for the concrete. Main physical and mechanical properties of concrete containing EAF slag as aggregate according to Fuller’s grading curve were experimentally investigated. Chemical and durability tests were performed to study the microstructure and analyse the behaviour of the conglomerate exposed to detrimental agents. Results showed that high substitution ratios of coarse natural aggregates are possible without decreasing mechanical properties of concrete. Conversely, replacement of fine natural aggregates with recycled ones seems feasible at lower substitution ratios only. Presence of calcium and magnesium oxides in the slag does not seem to represent a limit for the durability of concrete, due to their stabilization in crystalline lattice.

Flexural Behavior of Reinforced Concrete Beams with Electric Arc Furnace Slag Aggregates

This study estimates the flexural performance of reinforced concrete (RC) beams with electric arc furnace (EAF) oxidizing slag aggregates. EAF oxidizing slag is a byproduct of steel production. It is composed mainly of CaO and SiO2, which are similar to the chemical properties of natural aggregates. Simply supported RC beams having various types of aggregates were tested to evaluate the applicability of EAF oxidizing slag as a concrete aggregate. The moment-curvature relationship and crack patterns up to peak load as well as the effective moment of inertia and deflection of the specimens under service load were analyzed and compared with the experimental results of natural aggregate specimens. The experimental results showed that the specimens with EAF oxidizing slag aggregates exhibited similar flexural performance to that of the specimens with natural aggregates.

Use of Electric Arc Furnace Slag in Thin Skid–Resistant Surfacing

One of the major by–products of the steel production industry is Electric Arc Furnace (EAF) slag. In the field of research and development and in cooperation with the laboratory of EGNATIA ODOS SA, the current study focuses on the mechanical properties of electric arc furnace slag, as used in the thin, porous surfacing of Egnatia Odos highway. The in–situ measurements refer to two highway segments constructed in July 2007 and August 2008. The data collected is compared to the initial results of the mixture studies and the behaviour of the wearing course is examined in the time span of 30 and 41 months, subject to normal traffic and environmental weathering. The data obtained refers to three types of measurements, skid resistance, macro texture depth and permeability. The results show minor differences in between initial and later measurement. The data is also compared to skid–resistant layers with natural hard aggregates which were constructed at the same time period and were subject to identical environmental and traffic conditions on the Egnatia Odos highway. Comparison is made to a study on the P.A.TH.E. highway with similar skid resistant wearing courses of asphaltic concrete. Both results show the suitability of EAF slag aggregates to fully satisfy the technical specifications. The comparison to wearing courses made with natural hard aggregates highlights the superiority of artificial aggregates, primarily due to their enhanced mechanical properties.

Skid resistance performance of asphalt wearing courses with electric arc furnace slag aggregates

Metallurgical slags are by-products of the iron and steel industry and are subdivided into blast furnace slag and steel slag according to the different steel-producing processes. In Greece, slags are mostly produced from steelmaking using the electric arc furnace process, and subsequently are either disposed in a random way or utilized by the cement industry. Steel slag has been recently used, worldwide, as hard aggregates in wearing courses in order to improve the skidding resistance of asphalt pavements. At the Highway Laboratory, Department of Civil Engineering of Aristotle University of Thessaloniki research has been carried out in the field of steel slags, and especially in electric arc furnace (EAF) slag, to evaluate their possible use in highway engineering. In this paper, the recent results of anti-skidding performance of steel slag aggregates in highway pavements are presented.