Electric Arc Furnace Steel Slag Research Articles

Probabilistic risk assessment of residential exposure to electric arc furnace steel slag using Bayesian model of relative bioavailability and PBPK modeling of manganese.

Electric arc furnace (EAF) slag is a coproduct of steel production used primarily for construction purposes. Some applications of EAF slag result in residential exposures by incidental ingestion and inhalation of airborne dust. To evaluate potential health risks, an EAF slag characterization program was conducted to measure concentrations of metals and leaching potential (including oral bioaccessibility) in 38 EAF slag samples. Arsenic, hexavalent chromium, iron, vanadium, and manganese (Mn) were identified as constituents of interest (COIs). Using a probabilistic risk assessment (PRA) approach, estimated distributions of dose for COIs were assessed, and increased cancer risks and noncancer hazard quotients (HQs) at the 50th and 95th percentiles were calculated. For the residents near slag-covered roads, cancer risk and noncancer HQs were <1E - 6 and 1, respectively. For residential driveway or landscape exposure, at the 95th percentile, cancer risks were 1E - 6 and 7E - 07 based on oral exposure to arsenic and hexavalent chromium, respectively. HQs ranged from 0.07 to 2 with the upper bound due to ingestion of Mn among children. To expand the analysis, a previously published physiologically based pharmacokinetic (PBPK) model was used to estimate Mn levels in the globus pallidus for both exposure scenarios and further evaluate the potential for Mn neurotoxicity. The PBPK model estimated slightly increased Mn in the globus pallidus at the 95th percentile of exposure, but concentrations did not exceed no-observed-adverse-effect levels for neurological effects. Overall, the assessment found that the application of EAF slag in residential areas is unlikely to pose a health hazard or increased cancer risk.

Eco-friendly warm mix asphalt mixtures incorporating electric arc furnace steel slag as substitute to conventional aggregates

Eco-friendly warm mix asphalt mixtures incorporating electric arc furnace steel slag as substitute to conventional aggregates

Mechanical performance and environmental assessment of porous asphalt mixtures produced with EAF steel slags and RAP aggregates

Porous asphalt mixtures play a remarkable role in road pavement thanks to their advantages to drain water and reduce noise. To meet the always-increasing environmental needs, new porous asphalt mixtures are being developed with the addition of recycled materials. The present paper investigates the physical, mechanical, and functional characteristics of two porous mixtures made with electric arc furnace (EAF) steel slag and reclaimed asphalt pavement (RAP). The properties of the two recycled mixtures are compared with conventional porous asphalt produced with natural aggregates. An LCA analysis is performed with a cradle-to-gate approach to evaluate and compare the possible environmental benefits connected to the production of the experimental porous asphalt. The results coming from the laboratory investigation demonstrated higher mechanical and functional performances related to the use of EAF steel slag and RAP aggregates. The environmental assessment established a reduction of up to 25% of potential impact for the mixture produced with both artificial and recycled aggregates.

Comparative Environmental Analysis for Using Waste Polyethylene and Steel Slag in Semi-dense Asphalt Pavements

Abstract This study presents a life cycle assessment (LCA) evaluating the use of virgin materials, waste polyethylene (PE), and electric arc furnace steel slag (EAFSS) in semi-dense asphalt (SDA) surface courses, which is primarily used for low-noise pavements. Three types of SDA mixtures with virgin materials, waste PE, and EAFSS were prepared and water sensitivity tests were conducted to determine the mechanical performance. The LCA defined three scenarios using system expansion, namely (1) the reference scenario using virgin materials in SDA and disposal of waste PE and EAFSS by municipal solid waste incineration (MSWI) and landfill, respectively; (2) the test scenario using waste PE and straight run binder in SDA, with landfilling of EAFSS; (3) the test scenario using EAFSS in SDA, with the disposal of waste PE by MSWI. The data from the experiments, Swiss industries, official reports, and standard databases were used for the inventory analysis. The results show that compared to the reference, the scenarios using waste PE and EAFSS in SDA would reduce 15 % and 36 % of greenhouse gases emissions, respectively. The reason for the improved environmental performance when waste PE is used in asphalt can be attributed to the use of straight run binder to replace polymer-modified binder and the avoided MSWI. For the EAFSS scenario, the improved environmental performance is attributable to the avoided landfilling. The results also indicate that the recycling of waste PE and EAFSS in SDA would not have benefits in nonrenewable cumulative energy demand.

Manganese relative oral bioavailability in electric arc furnace steel slag is influenced by high iron content and low bioaccessibility

Electric arc furnace (EAF) slag is a rock-like aggregate produced with carbon steel and used for construction, including residential ground cover. It is enriched with manganese (Mn) and other metals, including iron (Fe), but because metals are bound in mineral matrices, in vitro bioaccessibility (BA) is limited. We conducted a relative bioavailability (RBA) study using F344 rats to assess Mn RBA from EAF slag ingestion, compared with Mn in diet. Mn and Fe were measured in liver, and Mn in lung and striatum, the target tissue of the brain. Mn levels in each tissue were fit by dose-to-tissue concentration (D-TC) curves. The D-TC relationship was the most highly significant for the linear model using liver Mn, and the RBA was 48%. The D-TC relationship in lung showed a positive slope for chow, but that for EAF slag was slightly negative, and the RBA was 14%. In comparison, the striatum D-TC remained relatively constant, supporting that homeostasis was maintained. Increased Fe was observed in the liver of EAF slag-dosed groups, suggesting that Mn absorption was inhibited by the high Fe content of slag. Lung and striatum D-TC curves demonstrated that systemic delivery of Mn from EAF slag ingestion is limited and support an RBA of 14% for risk assessment. Although Mn levels in slag are elevated compared with health-based screening guidelines, this study supports that incidental ingestion of Mn in EAF slag is unlikely to pose a neurotoxicity hazard due to homeostatic controls, low BA, and high Fe content.

Evaluation of high percentage of alternative aggregates for the production of hot mix asphalt surface layers

In the last decades, recycling of hot mix asphalt (HMA) materials became one of the major issue concerning the world of pavement engineering. As required by Italian technical specifications, pavements surface layers must be produced using high-quality aggregates, in order to meet performance in terms of mechanical and anti-skid properties. Inevitably, the extraction of virgin mineral aggregates and their decreasing availability encourage the use of recycled alternatives, such as electric arc furnace steel slag and municipal solid waste. This study evaluates the possibility to implement recycled aggregates, and others sustainable solutions, in the production of HMA surface layers. In particular, eleven mixtures were produced combining the use of recycled aggregates to polymers obtained from plastic waste recycling and basalt fibres obtained from mineral deposit productions. Laboratory and field results confirmed the validity of the ecological solutions proposed in terms of fundamental properties for surface layers, such as fatigue resistance, rutting and skid resistance.

Assessment of the influence of electric arc furnace slag as a non-conventional filler for Nitrile Butadiene Rubber

Reinforcement of polymers by the addition of particles filler is a complex phenomenon that depends mainly on the hydrodynamic effect and a complex interplay between polymer, filler, and interfacial region. Mineral fillers are usually adopted as low-cost extenders due to their lower cost.In this study, the influence of a waste material such as electric arc furnace steel slag is assessed as filler for Nitrile-Butadiene Rubber following experimental procedures and analytical calculations adopted for traditional fillers. It was found that the slag content affects the static and the dynamic properties by increasing the material's capability to storage and dissipate energy. In addition to an important contribution of the hydrodynamic effect, the presence of an increasing immobilized rubber fraction around the slag particles (quantified by a differential scanning calorimetry analysis) plays a central role. The slag stiffens the NBR composite; the increase of static tensile and dynamic shear storage moduli was found to be consistent with the Halpin-Tsai and Guth-Gold prevision models respectively. Moreover, the non-linear dynamic behavior was found to be well-fitted by the Kraus equation models. The reinforcing ability of the slag particles as filler was confirmed by the negative slope of the Kraus plot on swelling data.

Performance analysis of coloured microsurfacing with electric arc furnace steel slag as an aggregate replacement: a laboratory evaluation

ABSTRACT Coloured microsurfacing is a preventive maintenance method that, if used correctly, is well known to bring about economic and environmental benefits. The present work seeks to examine the possible use of electric arc furnace steel slag (EAF-SS) aggregates as a substitute for part of the conventional aggregates in the microsurfacing mix design to improve its performance. Beginning with an assessment of the steel slag (SS) properties both chemically and physically, the slag was incorporated in microsurfacing mixtures to replace control sample aggregates at five different dosages, namely 0, 10, 20, 30 and 40% (based on the total weight of aggregate), to determine the proper dosage. Specimens were examined using cohesion, loaded wheel and wet track abrasion tests. The results showed that the SS-bearing mixtures performed well, especially when the slag dosage was 30%. Experimental outcomes further indicated acceptable compatibility of the blends with SS aggregates and the asphalt emulsion, thanks to their good physical, chemical, and mechanical characteristics. These advantages enahanced the microsurfacing performance in terms of adhesion of asphalt binder to aggregates (by up to 36.3%), abrasion resistance (by up to 47.7%), bleeding potential (down by up to 48.0%) and vertical displacement (down by up to 45.9%).

Radiation shielding performance of seawater-mixed concrete incorporating recycled coarse aggregate and steel slag

Concrete production entails a high amount of freshwater consumption. Moreover, as heavy-weight concrete production is cost-inefficient for mass structures, such as radiation shielding facilities, the need for seawater and other recycled/waste materials to produce sustainable concretes for radiation shielding applications cannot be overemphasized. Hence, this paper investigates the radiation shielding performance of fresh water and seawater-mixed concrete mixes produced using various waste coarse aggregates, including recycled aggregate and electric arc furnace steel slag (EAF-SS). Partial simultaneous replacements of the two coarse aggregate types are also considered. Aimed at addressing material sustainability, a total of ten such concrete mixtures were designed and produced by varying the type of mixing water with different combinations of the normal and waste coarse aggregates while maintaining the cement content and water/cement ratio constants. These mixtures were then tested for their unit weight, compressive strength, and nuclear radiation response through gamma-ray intensity detection. The mixes' compressive strengths ranged from 30.8 to 49.8 MPa, all of which met the specifications for structural concrete. Linear attenuation coefficients were computed based on the radiation experimental results for the different mixes. Three of the specimens passed the minimum requirement to be considered heavy-weight concretes. Regardless of concrete strength, the unit weight of the mixes and the type of water (fresh versus seawater) used for mixing had an impact on radiation shielding performance. The maximum compressive strength was attained in the fresh water-mixed concrete fully incorporating EAF-SS as coarse aggregate – 13% over that of the concrete with natural aggregate. Moreover, the use of EAF-SS enhanced the radiation shielding performance of concrete by 13–19%. Using local seawater improves radiation shielding by 4–5% while pursuing sustainable concrete production for nuclear applications. A mixture's unit weight and chemical composition – particularly the existence of hematite – are crucial factors in the effectiveness of radiation shielding. The variations in gamma-ray transmission reductions between mixtures confirm the feasibility of the materials utilized.

Steel furnace slag aggregate for railway ballast: assessment of abrasion evolution by close-range photogrammetry

Electric Arc Furnace steel slag aggregate has potential for wider application in transport infrastructures. However, the use of steel slag aggregate in the railway ballast layer, as an alternative to natural high quality crushed rock, is still restricted in some countries. This is not consistent with the current sustainable construction paradigm. To demonstrate the potential of this material, in this study the authors characterized its morphology and performance, carrying out quantitative analyses on the abrasion and 3D morphology evolution of particles submitted to micro-Deval testing. The slag particles showed higher angularity and surface texture indices than a natural granite used as reference; retained these characteristics longer; and yielded comparable or lower surface wear. These findings support the potential use of slag aggregate as an alternative to railway ballast material.

Mass Concrete with EAF Steel Slag Aggregate: Workability, Strength, Temperature Rise, and Environmental Performance

Temperature control is the primary concern during the design and construction process of mass concrete structures. As the concrete production has an enormous negative environmental impact, the development of green mass concretes will eventually become as important as the thermal characteristics. Therefore, this paper investigates the use of Electric Arc Furnace (EAF) steel slag aggregate for the partial replacement of the natural aggregate in the production of mass concrete. The impact of EAF steel aggregate on mass concrete workability, strength, and thermal behaviour was analysed. In addition, a cradle-to-gate LCA study was conducted to evaluate the environmental footprint and sustainability potential of the tested mass concrete mixtures. The study results suggest that the use of EAF steel slag aggregate in combination with a low-heat cement with a high content of blast furnace slag can significantly lower the temperature, reduce the environmental impact, and increase the sustainability potential of mass concrete, while at the same time providing sufficient workability and compressive strength. The study results indicate that EAF steel slag can be upcycled into an aggregate for the production of green mass concrete mixtures.

Recycling of crushed concrete and steel slag in drainage structures of geotechnical works and road pavements.

A crushed concrete aggregate, processed from construction and demolition waste and a siderurgical aggregate, processed from electric arc furnace steel slag, were selected based on their very high availability worldwide and known technical feasibility to be used in construction works. Given the association of their presence to the possibility of reducing the drainage capacity of unbound granular layers of road pavements and drainage structures which they may be associated with, there are studies and regulations that do not recommend their use. The causes that are at the origin of restrictions are mainly the possibility of formation of tufa and recementation phenomena. This behaviour has also hampered their recycling in drainage structures of geotechnical works. Therefore, it was considered that it would be relevant to investigate the drainage capacity of those recycled aggregates, using a leachate produced in a municipal solid waste landfill and tap water. To reference their behaviour, two natural aggregates, a basalt and a limestone, were also studied under identical test conditions. The results obtained showed no reduction in the drainage capacity of the recycled aggregates, similarly to what was observed with the natural aggregates. The possibility of building drainage structures with the tested aggregates is verified.

Metal-Nails Waste and Steel Slag Aggregate as Alternative and Eco-Friendly Radiation Shielding Composites

Metal waste recycling has become a global requirement owing to its environmental benefits and powerful economic activity. Metal nail waste (MNW) is a byproduct of metal nail manufacture. MNW has an equal size, contains a high ratio of iron, and has a high specific gravity comparable to normal aggregate. We present MNW recycling as a partial replacement for fine aggregates and electric arc furnace steel slag (EAFSS) as coarse aggregates to produce sustainable heavyweight concrete (HWC). Our main research aim was to study the radiation shielding and mechanical properties of sustainable HWC by partially replacing MNW with 10, 20, 30, and 40% sand. EAFSS is a coarse aggregate for 60% of the total volume. Fresh and hardened properties of HWC are presented. Furthermore, we analysed the internal structure of HWC mixes using a scanning electron microscope. Our results showed the positive effects of MNW on the unit weight of concrete. The density of HWC mixes ranges between 2650 and 3170 kg/m3. In addition, MNW contributes to increasing the compressive strength of concrete mixes with their use of up to 30%. Therefore, the MNW ratios improved the failure behaviour of HWC mixes. The improved linear attenuation coefficient of HWC mixes was due to using MNW ratios and higher densities than the reference mix.

Friction Characteristics of Open Graded Asphalt Friction Courses with BOF and EAF Steel Slag Aggregates

Friction properties of open graded asphalt friction course (OGAFC) mixtures play an essential role in ensuring traffic safety, especially under wet weather conditions. This study evaluated the friction characteristics of basic oxygen furnace (BOF) and electric-arc furnace (EAF) steel slag aggregate incorporated OGAFC mixes. Nine sets of OGAFC mixes were fabricated using five percentage replacements (0%, 25%, 50%, 75%, and 100%) of the coarse natural aggregate fraction by BOF and EAF steel slags. The effect of modified binder type (polymer and crumb-rubber modified) on the frictional characteristics of OGAFC mixes was also examined. The principal friction test devices used were the British pendulum tester and dynamic friction tester. Multiple friction performance aspects were studied: (1) effect of surface condition (dry, wet, and ponding) on the measured friction coefficient; (2) separate evaluation of adhesion and hysteresis friction components; (3) variation of friction coefficient with varying slip speeds, and (4) friction performance later in the OGAFC service life using artificially polished aggregates, and comparison of the performance with unpolished aggregates. Results revealed that the use of steel slags in OGAFC mixes considerably enhanced the frictional characteristics and that the skid resistance of OGAFC-BOF mixes was better than that of OGAFC-EAF mixes. Frictional resistance of the mixes was found to increase with an increase in steel slag content. OGAFC mixes comprising polished steel slag aggregates also showed promising results with the increment in steel slag content. The findings also indicated that OGAFC-CRMB mixes perform better than OGAFC-PMB mixes.

Extraction of Manganese Element from Electric Arc Furnace Steel Slag (EAFS) by Liquid-liquid extraction (LLE) method

This research investigates manganese (Mn) extraction from Electric Arc Furnace Steel Slag (EAFS) by using the Liquid-liquid extraction (LLE) method. The chemical analysis was done on the slag using X-ray fluorescence, X-ray diffraction, and atomic absorption spectroscopy. This work consisted of two parts: the first was an extensive study of the effect of variables that can affect the leaching process rate for Mn element from slag (reaction time, nitric acid concentration, solid to liquid ratio, and stirring speed), and the second part evaluates the extraction of Mn element from leached solution. The results showed the possibility of leaching  83.5 % of  Mn element from the slag at a temperature of 25°C, nitric acid concentration 2 M, time 90 min, S / L ratio 1/100, and stirring speed 700 rpm. 94.7% extraction of Mn was accomplished from nitric acid solutions by using Octyl Pyro Phosphoric Acid (OPPA) in kerosene at contact time for 12 min, 50%OPPA -kerosene, stirring speed 900 rpm, and organic to the aqueous phase (O/A) of 4/1. Kerosene was the most important diluting agent in extracting Mn, compared to benzene and toluene.

Development of an electric arc furnace steel slag-based ceramic material for high temperature thermal energy storage applications

This paper details the development process of ceramics made out of 100% electric arc furnace (EAF) steel slag, to be used as a shaped homogenous thermal energy storage (TES) media in packed-bed thermocline systems for high-temperatures industrial waste heat recovery, concentrated solar power (CSP), and Carnot batteries applications, among others. The main objective of this study was to investigate the influence of different process parameters on the properties of the resulting ceramics. The samples have been characterized in terms of bulk density, apparent solid density, and water absorption to identify the best values for different process parameter. The best properties were obtained for samples prepared with heat-treated slag powders, pressed at 300 MPa and fired at 1300 °C for 8 h under a static air atmosphere. The optimal bulk density was 3.1 g/cm3, and the water absorption was 1.2%wt. The measured specific heat capacity was 1026, 1181 and 1216 J/(kg.K) at 200, 400 and 600 °C, respectively, while the thermal conductivity values were 1.53, 1.50 and 1.37 W/(m.K) at the same temperatures. This work confirms the feasibility of manufacturing TES ceramics out of EAF steel slags, using equipment and techniques well-known in the refractory industry.

Predicting the abrasion loss of open-graded friction course mixes with EAF steel slag aggregates using machine learning algorithms

This study presents a comparative assessment of machine learning techniques for modeling the abrasion loss (AL) of open-graded friction course (OGFC) mixes. The proposed approach is Orthogonal Matching Pursuit (OMP), Huber Regressor (HR), Lasso Lars CV (LLCV), Lars CV (LCV), and Ridge Regressor (RR). To construct and validate the proposed models, a sum of 228 experiments of OGFC mixes with different proportions of natural aggregates and electric arc furnace (EAF) steel slag were performed. Based on the analyses with 4 different combinations of input parameters, the proposed OMP model exhibits the most accurate prediction of AL of OGFC mix in both training and validation phases. Comparison of results of the developed models indicated that the OMP model has the potential to be a new alternative to assist engineers/practitioners in estimating the AL of OGFC mixes. In addition, the effect of % replacement of natural aggregates with electric arc furnace steel slag can also be studied.

Laboratory Evaluation of Fiber-Modified Asphalt Mixtures Incorporating Steel Slag Aggregates

Vigorous and continued efforts by researchers and engineers have contributed towards maintaining environmental sustainability through the utilization of waste materials in civil engineering applications as an alternative to natural sources. In this study, granite aggregates in asphaltic mixes were replaced by electric arc furnace (EAF) steel slag aggregates with different proportions to identify the best combination in terms of superior performance. Asphalt mixtures showing the best performance were further reinforced with polyvinyl alcohol (PVA), acrylic, and polyester fibers at the dosages of 0.05%, 0.15%, and 0.3% by weight of the aggregates. The performance tests of this study were resilient modulus, moisture susceptibility, and indirect tensile fatigue cracking test. The findings of this study revealed that the asphalt mixtures containing coarse steel slag aggregate exhibited the best performance in comparison with the other substitutions. Moreover, the reinforced asphalt mixtures with synthetic fibers at the content of 0.05% exhibited an almost comparable performance to the unreinforced asphalt mixtures. Modifying the asphalt mixtures with PVA, acrylic, and polyester fibers at the proportion of 0.15% have improved the fatigue cracking resistance by 41.13%, 29.87%, and 18.97%, respectively. Also, the fiber-modified asphalt mixtures with PVA, acrylic, and polyester have enhanced the fatigue cracking resistance by about 57%, 44%, and 39%, respectively. The results of the resilient modulus demonstrated that as the fiber content increase, the resilient modulus of the reinforced asphalt mixtures decreases. Therefore, introducing synthetic fibers at the content of 0.3% has slightly decreased the resilient modulus in comparison with unreinforced mixtures. On the other hand, the results of the mechanistic-empirical pavement design showed that the reinforced asphalt mixes with a high content of synthetic fibers have shown lower service life than the control mixes due to the low resilient modulus. On the contrary, based on the laboratory results, the asphalt mixes incorporating PVA, acrylic, and polyester fibers at the proportion of 0.15% have shown the potential to reduce the thickness of the asphalt layer by about 14.9%, 11.80%, and 8.70%, respectively.

Shear strength assessment of reinforced concrete components containing EAF steel slag aggregates

Electric Arc Furnace (EAF) slag can be reused as aggregate in Portland cement concrete mixes. The addition of EAFS and other waste co-products (fly ash, blast furnace slag) will modify the binding properties and will, importantly, enhance the global sustainability of such concretes. These mix designs offer acceptable pumpability and self-compaction in the fresh state and can be reinforced with fibers. In this study, eight different concrete mixes are designed within the range of medium-strength concretes (30–50 MPa) and are characterized in both the fresh and the hardened state. Large concrete volumes are used to pour reinforced beams, which are then subjected to small-span high-load tests to evaluate their resistance to shear stress, by analyzing two types of transversal (shear) reinforcement. The tests yielded promising results, contributing additional evidence on the viability of using recycled EAFS aggregate in structural applications. The mechanical behavior of these concretes was closely correlated with the strength predictions calculated with the formulas listed in various international standards.

Application of electric arc furnace slag for stabilisation of different tropical soils

ABSTRACT Steelmaking wastes have been reused in civil construction to decrease environmental damages. This work evaluated the use of fines of oxidising electric arc furnace (EAF) steel slag (FEAF) as stabilising agents of two different soils Tests for geotechnical characterisation of soils and chemical, physical, and morphological characterisation of FEAF were carried out. Natural soils and soil-FEAF mixtures were subjected to standard Proctor compaction, unconfined compression strength (UCS), California Bearing Ratio (CBR), and resilient modulus (RM) tests. FEAF provided UCS increases up to 128%, maximum dry density increases up to 6% and optimal moisture content reductions up to 10%. The highest improvements were provided by 15% of FEAF (UCS increases from 7 to 56 days of A-7-5(19) and A-2-7(0) soils were 60% and 21%, respectively). Regardless of the curing period, CBR index of A-7-5(19) soil with 15% FEAF was 60–65% of CBR index of A-2-7(0) soil containing 15% FEAF. Similar reductions (27–29%) in CBR swelling were observed in both soils. Incorporation of 15% FEAF into A-7-5(19) and A-2-7(0) soils provided RM increases of 30% and 45%, respectively. Mechanical properties increases were attributed to filler effects and improvements in cementitious reactions FEAF improved soils’ performance, enabling their use in pavement design and earthworks.