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This study investigates the thermal properties of asphalt mixtures incorporating steel slag as a potential substitute of natural aggregates in hot mix asphalt, precisely the BBTM11B type. The thermal properties were analysed using the QuickLine equipment following the ASTM D5930 standard. Experimental tests were conducted to measure the cooling curves of different mixtures at different compaction levels, while numerical simulations using the finite element method (FEM) were employed to predict the cooling curves. The experimental observations indicate that as the substitution levels of steel aggregates increase, the samples exhibit lower thermal conductivity and specific heat. It was also shown that the numerical simulation successfully estimated the temperature evolution of the mixtures, enabling the prediction of their thermal behaviour. The study suggests that mixtures containing steel slag, although they need a longer cooling time, exhibit a wider compaction window, allowing for better compaction and improved mechanical performance compared to mixtures without this material., The first author acknowledges the Generalitat de Catalunya (GENCAT) and L′Agència de Gestió d′Ajuts Universitaris i de Recerca (AGAUR) for the scholarship “Grants for the recruitment of new research staff FI 2021 (Ref: 2021 FI B00949)”. The second and third authors acknowledge the support from MCIN / AEI and FEDER Una manera de hacer Europa for funding their research via project PID2021-122676NB-I00. All the authors thank Adec Global for the steel slags aggregates and the OHLA group for the generous donation of bitumen, granite, limestone, and filler used in this research., Peer Reviewed, Postprint (published version)

Compilation of all available raw data for the publication "Metal Deportment in Complex Secondary Raw Materials: The Case of Vanadium in Basic Oxygen Furnace Slags". List of Supplementary Information Table A 1: Compilation of elements analyzed by XRF including lower and upper limits of determination (LoD). Table A 2: Compilation of the subsample designations of the three BOS samples analyzed for the XRF and XRD as well as the MLA and EPMA analyses. All subsamples correspond to representative subsets of the bulk sample. Table A 3: Compilation of the EPMA measurement parameters with spectrometer position (Spec), lower background (LB), upper background (UB), dwelltime on peak (DTP) and background (DTB) and the complete list of reference materials. Table App 4: Compilation of all major and minor element contents determined by XRF recalculated as “water-free” and normalized to 100 wt.-%. Table A 5: Comparison of LOI values for one sample each of the delivered material "as delivered" and fully hydrated. Table A 6: Compilation of significant differences between the samples with regard to the chemical composition. Table A 7: Detailed compilation of the results of the MLA measurements of all investigated samples. Table A 8: Compilation of the phases predefined for EPMA analyses and the number of measurements performed and usable for further MLA and deportation analyses. Table A 9: Complete summary of all EPMA data used for the deportment analysis (xls File).

Basic oxygen furnace (BOF) slag is a waste from the steel-making process characterised by its low hydraulic behaviour and heavy metals content. This study investigates activation of BOF slag with disodium oxalate to enhance the early hydration kinetics, microstructure development and heavy metals retention to develop it as a 100% replacement alternative for ordinary Portland cement. The results reveal that the activator boosts the reactivity not only of brownmillerite and calcium silicate but also Mg-wuestite. The main products formed are hydrogarnets and calcium-silicate-hydrate (C-S-H) gel. The maximum dosage added of 3 wt.% reached sufficient strength of 32.8 MPa at 28 days, being the most promising mixture. Leaching results of heavy metals are below the Dutch Soil Quality Decree limits. In summary, the BOF slag-oxalate cement offers an attractive approach for the future of steel-making and the building materials industry.

With the increasing demand for metalliferous and mineral raw materials and the consequent depletion of the global natural resource base, the possible utilization of secondary raw material sources is receiving more and more attention. In the present study, we present results from a detailed vanadium deportment study of three basic oxygen furnace slag (BOS) samples known to containing elevated bulk concentrations of vanadium. Complementary analytical methods that were used to quantify the abundance and composition of V-containing phases include SEM-based automated mineralogy, X-ray fluorescence analysis, and X-ray powder diffraction as well as electron probe microanalysis. The vanadium deportment was quantified using Monte-Carlo simulations of the data obtained from automated mineralogy and electron microprobe analysis. The total V concentrations identified by XRF are between 1.7 and 2.2 wt.% V. The most important hosts of vanadium are larnite-, brownmillerite- and portlandite-solid solutions. In two samples Ca carbonates also significantly contribute to the V deportment, while wuestite, lime, and native iron do not contribute significantly to the vanadium deportment. A thorough consistency check identifies considerable uncertainties in the density of the V-bearing phases as the most likely reason to explain remaining discrepancies between measured and calculated V values

Veliki industrijski razvoj je poslednjih decenija izazvao nekontrolisano iskorišćavanje prirodnih resursa i degradaciju životne sredine, što je dovelo do zabrinutosti društva za posledice koje utiču na stanje životne sredine. Izgradnja putne infrastrukture je jedan od glavnih faktora koji doprinose globalnom zagrevanju u oblasti građevinarstva. Procenjeno je da svaki metar izgrađenog puta godišnje izazove emisiju gasova staklene bašte u iznosu od 14,7 kg CO2ek, gde su faza ekstrakcije i proizvodnja materijala glavni procesi koji doprinose ukupnoj emisiji ugljenika i potrošnji energije. (1) To je razlog zašto izbor materijala za izradu kolovoznih konstrukcija direktno utiče na lokalno zagađenje i degradaciju životne sredine. U ovom radu je razmatrana upotreba bakarne i čelične zgure kao delimične zamene prirodnog agregata u asfaltnim mešavinama i analiziran je životni ciklus kolovoznih konstrukcija, napravljenih od pomenutih mešavina. Eksperimentalna istraživanja su pokazala da upotreba bakarne i čelične zgure u asfaltnim mešavinama dovodi do povećane potrošnje veziva prilikom spravljanja mešavina i do povećavanja transportne mase, što dovodi do povećane potrošnje energije i negativno utiče na globalno zagrevanje i zdravlje ljudi. Međutim, upotreba ovih industrijskih nusproizvoda u asfaltnim mešavinama dovodi do uštede prirodnih agregata i rešava problem deponovanja ovog otpadnog materijala na odlagalištima, što je veoma značajno sa ekološkog aspekta., In recent decades, large-scale industrial development has caused uncontrolled exploitation of natural resources and environmental degradation, which has led to society's concern about the consequences affecting the state of the environment. The construction of road infrastructure is one of the main factors contributing to global warming in the construction industry. It has been estimated that each meter of road constructed annually causes greenhouse gas emissions of 14.7 kg CO2eq, where the extraction phase and material production are the main processes that contribute to the total carbon emissions and energy consumption. (1) This is the reason why the choice of materials for the construction of pavement structures directly affects local pollution and environmental degradation. In this paper, the use of copper and steel slag as a partial replacement of natural aggregate in asphalt mixtures was discussed and the life cycle of pavement structures made from the aforementioned mixtures was analyzed. Experimental research has shown that the use of copper and steel slag in asphalt mixtures leads to increased consumption of binder for preparation of mixtures and to an increase in transport mass, which cause increased energy consumption and negatively affect global warming and human health. However, the use of these industrial by-products in asphalt mixtures leads to the saving of natural aggregates and solves the problem of depositing this waste material in landfills, which is very significant from an environmental point of view.

Basic oxygen furnace (BOF) slag from steelmaking could be applied as a binder in building materials, reducing the CO2 footprint and solid waste, which is relevant for industrial waste management and circular economy. However, its use is mostly restricted because its hydraulic activity is poorly understood. The BOF slag was hydrated in this study, and its reaction products were systematically characterized using XRD, QXRD, and SEM/EDX-based phase mapping. Internal consistency checks of the data were performed between the analytical techniques. The results revealed that the composition of the amorphous hydration products could be identified and quantified, and the main hydration products were hydrogarnets and C-S-H gel. An extended milling process significantly improved the reactivity, and all the major slag phases, including wüstite, participated in the reaction. Brownmillerite formed hydrogarnets during the first 7 days of hydration. The new hydration products contributed to the immobilization of vanadium and chromium. Particle size played an important role in the amount of C2S reacting, the composition of the hydrogarnets and C-S-H gel, their proportions, and the immobilization capacity. Based on the findings, an overall hydration reaction was developed.

As part of the RILEM Technical Committee TC 279-WMR on valorisation of waste and secondary materials for roads. Task Group 3 used various waste aggregates as a replacement for natural aggregates in asphalt mixtures, namely, construction and demolition waste, recycled concrete aggregates and steel slag. For this interlaboratory exchange program, the mixtures were produced by substituting various amounts of virgin aggregates with the aforementioned waste aggregates in various fractions. The results from eight laboratories were compared to a reference mixture in each laboratory with conventional aggregates. The mechanical performance of these mixtures using such alternative aggregates indicates that bituminous mixtures prepared with the investigated waste aggregates required higher amounts of bitumen but had acceptable volumetric properties. Furthermore, they had better mechanical performance, regardless of the source of recycled aggregates. The results show that such aggregates 76 can be a viable option for use in roads, thereby contributing to the zero-waste society and reducing the use of natural aggregates. However, the adaptation of quality control/acceptance criteria and pavement design as well as the development of specific research aimed at assessing the environmental viability and life cycle sustainability of such materials seem necessary.

Steelmaking in the Electric Arc Furnace (EAF) generates around a 40 wt. % of slag, a solid by-product which might contain relatively high amounts of iron (about 35 wt. % in iron oxides (FeO-Fe2O3)) and other valuable metals, such as manganese (approx. 6 wt. % as MnO) and chromium (approx. 2.5 wt. % as Cr2O3). Although steel slags find today many applications, mainly as road-making aggregate, the development of new, sustainable, metal recovery methodologies from slag is fundamental to prevent the permanent loss of valuable alloying elements and to enhance the circular economy of the steelmaking sector. This study explores thermodynamically the potential of hydrogen gas as a reducing agent to replace the carbonaceous substances currently used in key metallurgical processes of steel by-product valorisation, aiming at reducing the related CO2 emissions and at maximizing the metallic recovery. Process modelling of the reduction of iron oxides present in EAF slag (Fe-O-X system, where X= Si, Mg, Ca, Al) was performed using the FactSage software. Energy and mass balance calculations were obtained during the reduction of the input slag mixture at 1750 °C by injection of variable amounts of hydrogen gas at room temperature. The results were compared with those obtained analogously by the addition of variable amounts of carbon powder. The results of this study will allow us to understand the chemical reactions and the basic thermodynamic aspects of the processes occurring during the hydrogen-based reduction of EAF steel slags to reduce the CO2 emissions from the established process metallurgy and by-product valorisation routes.

The objective of this research is to determine the influence of slag as a global aggregate on compressive strength, bending and workability for a concrete f'c=20594 kPa. Steel slag was used in 10%, 15% and 20% as fine aggregate, in this way an alternative for the use of recycled materials is shown, in order to create an efficient and economical concrete, as well as friendly with the environment, where there is a large amount of steel slag, coming from workshops and companies dedicated to metal structures. This is due to the fact that they use steel welding, in order to minimize environmental contamination, since it would be shown that the steel slag would have a good behavior for the development of an experimental concrete. The method used is quantitative, using data observation panels as a data collection tool, they use inferential statistics of the data obtained to demonstrate hypotheses. It was concluded that the breakage, wear and elasticity tests carried out at 7, 14 and 28 days provided the optimal design to use 10% for the use of recycled steel slag in the three pre-established objectives, La presente investigación tiene como objetivo determinar la influencia de la escoria como agregado global en la resistencia a la compresión, flexión y trabajabilidad para un concreto f´c=20594 kPa. Se utilizó la escoria de acero en 10%, 15% y 20% como agregado fino, de esta manera se muestra una alternativa para el uso de materiales reciclados, con el fin de crear un concreto eficiente y económico, así como también amigable con el medio ambiente, donde hay mucha cantidad de escoria de acero, proveniente de talleres y empresas dedicadas a las estructuras metálicas. Esto debido a que utilizan soldadura de acero, con el fin de minimizar la contaminación ambiental, dado que se demostraría que la escoria de acero tendría un buen comportamiento para el desarrollo de un concreto experimental. El método empleado es cuantitativo utilizando como herramienta de recolección de datos paneles de observación de datos, utilizan estadísticas inferenciales de los datos obtenidos para demostrar hipótesis. Se concluyó que las pruebas de rotura, desgaste y elasticidad realizadas a los 7, 14 y 28 días proporcionaron el diseño óptimo a usar el 10% para el uso de escoria de acero reciclada en los tres objetivos preestablecidos

Due to the growing population, waste generation and food supply industries need to move towards a circular economy and take advantage of by-products. Metallurgical slag is a main by-product during steel production which contains several valuable minerals and can be used for several further applications, including water purification and agriculture. This thesis has a focus on the issue(s) that need to be assessed to be able to determine the suitability of Petrit-E steel slag from Höganäs AB for agricultural use after it has been used for water purification. This slag by-product has been tested and it was successful to purify wastewater from phosphorus (P). The use as a fertilizer is most promising because it contains the major fertilizer substances and it contains P which is a limited resource. Calculations were done for the mean value and standard deviation of the substances for three years and after for Cr (chromium) and Ni (nickel) contents in Petrit-E because these two metals that are present in the slag and are regulated in the regulation for limit values. The total contents of Cr and Ni were higher than the limit values so there are these two metals that need to be assessed further. Since Petrit-E is not a sludge and not a virgin material either, it requires other methods such as leaching tests by accredited laboratories. These tests are suitable for risk assessments and to estimate the amounts of metal availability for leaching. Leaching tests based on the site specific (local) chemical and physical processes and characteristics in the soil are necessary to estimate the suitability of Petrit-E.

The purpose of this study is to determine the physical and mechanical properties of concrete with ASTM A36 grade steel shavings, and to carry out a comparative study with traditional concrete. 36 specimens were taken as a sample and steel shavings were used at 0,6%, 1,5 and 6% as fine aggregate. The chip was obtained from the lathes of the company SMF Sagitario in the City of Lima. The research design is quasi-experimental and longitudinal; the data collection technique was observation. Inferential statistics were used to verify the hypothesis, where the results indicated that there are significant differences between traditional concrete and concrete with fine aggregate (Sig.=.000). Concluding that traditional concrete is superior to compressive and tensile strength at 7, 14 and 28 days of age, El presente estudio tiene como finalidad determinar las propiedades físicas y mecánicas del hormigón con virutas de acero de grado ASTM A36, y realizar un estudio comparativo con el hormigón tradicional. Se tuvo como muestra 36 probetas y se utilizó la viruta de acero en 0,6%, 1,5 y 6% como agregado fino. La viruta se obtuvo de los tornos de la empresa SMF Sagitario en la Ciudad de Lima. El diseño de la investigación es cuasi experimental y de corte longitudinal, la técnica de recolección de datos fue la observación. Se utilizó la estadística inferencial para la constatación de hipótesis, donde los resultados indicaron que hay diferencias significativas entre el hormigón tradicional y el hormigón con agregado fino (Sig.=.000). Concluyéndose que el hormigón tradicional es superior a en resistencia a la compresión y tracción realizadas a los 7, 14 y 28 días de edad

The present investigation was based on the innovation and elaboration of a hot asphalt mix (HMA) due to the premature deterioration of flexible pavements, and low capacity to fulfill its useful life. Then, it is recognized the need to ensure a good quality of materials for the asphalt mix and a search for a new material that can give greater durability and avoiding premature deterioration of the pavement. Thus, the incorporation of steel slag for the HMA design was evaluated with the objective to determine the stability and flow of the hot asphalt mixture incorporating steel slags. To achieve this, the Marshall methodology was developed with a percentage of steel slag with respect to the coarse aggregate in 0% - 15% - 25% - 50% - 75%. The results obtained, in terms of quality of the aggregates, complied with the standards of quality. It was concluded that the modified asphalt mixture with 15% steel slag is the best combination, in the same way this percentage complies for light-medium traffic, the remaining combinations (25% - 50% - 75%) only comply for light traffic. It was possible to increase the stability and flow of the incorporated asphalt mixture up to a maximum of 25% for a HMA with respect to the control mixture., La presente investigación se basó en la innovación y elaboración de una mezcla asfáltica en caliente (MAC), debido al deterioro prematuro de los pavimentos flexibles, y poca capacidad de cumplir con su vida útil. He aquí la necesidad de asegurar una buena calidad de materiales para la mezcla asfáltica y una búsqueda de nuevo material que sea capaz de dar mayor durabilidad y evitar un prematuro deterioro del pavimento. Se evaluó así la incorporación de escoria de acero para el diseño de MAC, con el objetivo de determinar la estabilidad y flujo de la mezcla asfáltica en caliente incorporando escorias de acero. Para esto, se empleó la metodología Marshall con un porcentaje de escoria de acero respecto al agregado grueso en 0% - 15% - 25% - 50% - 75%. Los resultados obtenidos, en cuanto a calidad de los agregados, cumplieron con los estándares de calidad. Se concluyó que la mezcla asfáltica modificada con la escoria de acero al 15% es la mejor combinación, de igual forma, este porcentaje cumple para tránsito liviano, mediano, al 25% - 50% - 75% solo cumplen para transito liviano. Se logró aumentar la estabilidad y flujo de la mezcla asfáltica al incorporar hasta un máximo de 25% para una MAC respecto a la mezcla de control.

A self-compacting steel slag epoxy resin concrete (SERC) was designed with steel slag as aggregate and epoxy resin as binder for rapid repair of road expansion joints and pavement. At the same time, a group of self-compacting basalt epoxy resin concrete (BERC) with basalt as coarse aggregate and limestone as fine aggregate was set up as the control group. The element analysis and micro morphology of SERC and BERC were studied by X-ray fluorescence spectrometry (XRF) and scanning electron microscope (SEM) to reveal the strength-forming mechanism of the two epoxy resin concretes. The cube compression test and Marshall stability test were used to study the effect of the strength formation rate and temperature of SERC and BERC on the strength. In addition, the high-temperature stability, low-temperature crack resistance, water damage resistance, fatigue resistance and interlayer bonding properties of SERC and BERC were also studied. The results showed that both SERC and BERC have good mechanical properties, high temperature properties and good bonding properties, and the low-temperature crack resistance and fatigue properties of SERC are better than that of BERC. According to the verification of the actual project that has been in service for one year, SERC can be perfectly used for road expansion joints., Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Pavement Engineering

Thermal energy storage represents a crucial element to increase solar power dispatchability. Within sensible heat storage in solid media, concrete is considered a low-cost alternative to be further developed and therefore, this has been addressed in this paper. Four concrete dosages were designed, combining each type of considered cement, ordinary Portland and calcium aluminate cement, with each type of considered aggregate, silico-calcareous and a steel slag. Thermo-mechanical properties of concrete were studied before and after 10 thermal cycles from 290 ¿C to 700 ¿C. Maximum operating temperature and heating rates were selected accordingly to the targeted application, a concentrating solar power (CSP) tower plant. At macro-level, results show thermal cycle stability of concrete with steel slag aggregate in both cement types. On the contrary, at micro-level, the petrography analysis shows the lack of bonding between steel slag aggregate and the cement paste. In contrast, concrete mixtures containing silico-calcareous aggregates collapse after thermal cycling., Peer Reviewed, Postprint (published version)

A variety of excess material is produced in the processes used in the scrap-metal based steel industry. The largest stream of material, by volume, is steel slag. Since slag material has very different properties and wide differences in its chemical composition its usage can be found in different sectors. The increased understanding of slag and its properties has made companies less prone to divert this material to stockpiling or landfills, and slag is therefore being used today in various engineering applications. Making better use of these materials, in an eco-friendly way, is essential in order to make the industry more sustainable and protect the environment and human wellbeing. This study aims to explore opportunities for making better use of excess materials in the scrap based steel industry in Sweden, using three methods: A case-study, a literature review and semi-structured interviews. The case study were conducted at Uddeholms AB in Hagfors and identified the streams of by-products from the steel-casting process. Steel-slag was identified as the largest material stream, by volume, and its specific usage was discussed further. The literature review aimed at compiling knowledge about practices for making good use of steel-slag in Europe and found a total of twelve usages, with the majority of the literature focused on the construction sector. Lastly a series of interviews were conducted with respondents from the scrap-metal based industry in Sweden to get a collective view on drivers and barriers for finding better usage for excess materials. Most of the respondents wants to see changes in current legislation, combined with a better dialogue between the companies and authorities to prevent bureaucratic and time-consuming processes. An improved dialogue is also considered important to prevent a situation where authorities make different decisions for similar cases., Hur kan restmaterial från stålindustrin användas för att minska uttaget av naturresurser? Ett vanligt användningsområde av exempelvis stålslagg är som konstruktionsmaterial vid sluttäckning av deponier. Genom att använda slagg för detta ändamål kan mängden deponerat material minska, samtidigt som man kraftigt minskar behovet av vanligt täckmaterial, såsom grus och jord. Stålslagg kan även användas inom flera samhällsviktiga funktioner som till exempel väg-anläggning, markstabilisering, avloppsvattenrening samt inom jordbruk. Detta innebär att en biprodukt från stålindustrin kan ses och användas som en resurs för samhället. Trots uppvisade fördelar deponeras fortfarande restmaterial som slagg varje år. Varför nyttjas inte restmaterial från stålindustrin som resurs i andra industrier? Denna studie visar att det finns barriärer och utmaningar kring sådana typer av samarbeten, men även drivkrafter för att överkomma dessa. Restmaterial från industriella processer är en oundviklig konsekvens, och återbruk kommer alltid att utgöra en utmaning för en cirkulär ekonomi i ett hållbart samhälle. Idag deponeras material som klassas som farligt avfall, en riskfylld och kostsam process vars långtidseffekter är svåra att förutse. För att minska mängden deponerat material, och samtidigt öka resurseffektiviteten av restmaterial vi själva producerar, måste fokus skiftas till bättre resursutnyttjande. Ett sätt är genom så kallad ’industriell symbios’, där ett avfall från en process ses som råvara i en annan. Att bilda symbioser mellan företag kantas av utmaningar och hinder. Denna studie undersökte hur den svenska stålindustrin ställer sig till resursoptimering och samarbete för att öka denna, med speciellt fokus på stålslagg. Resultaten visar att det finns ett flertal användningsområden för slagg, huvudsakligen som konstruktionsmaterial, och tyder på en stor potential för industrin att utforska alternativa användningar. Genom intervjuer med aktörer inom stålindustrin har dessa förklar

To optimize the pore skeleton structure of pervious concrete to enhance its phosphorus (P) removal from stormwater, small-sized adsorptive aggregate (1–2 mm steel slag) and large-sized natural aggregate (2–5 mm basalt), are applied for the manufacture of two-sized aggregate pervious concrete. Physico-mechanical properties, adsorption performance and freeze–thaw resistance are investigated. The results show that the small-sized steel slag aggregate fills the pores between the large-sized natural aggregates and reduces the porosity and permeability of pervious concrete, significantly improving the mechanical strength and freeze–thaw resistance. The pervious concrete in this study shows an excellent P-adsorption capacity, all P is removed from the aqueous solution with an initial concentration of 168 mg/L and 307 mg/L. The harmful elements (Cr, Sr and V, etc.) leached from the concrete are lower than the maximum limit value. The orthogonal results show that cement and steel slag are the main factors affecting the P-adsorption performance of pervious concrete. Based on the current results, sample 3 (cement: 350 kg/m3, sand: 500 kg/m3, W/C: 0.37, 1–2 mm steel slag: 1385.8 kg/m3 and 2–5 mm basalt: 361.3 kg/m3) shows good P-removal capacity, which is an optimal mix for pervious concrete to remove P from stormwater, with suitable strength and durability.

Evaluating the structure of soil prior to building construction is valuable in a large variety of geotechnical and civil engineering applications. To built an effective framework for assessing the strength of the stabilised soil, the presented workflow includes a complex approach of simplex lattice design and X-ray diffraction for the analysis of soil structure. Different from the traditional in situ measurements, we propose a statistical framework for effective decision-making on binder combination to stabilise soil collected in three localities of Southern Sweden—Bromölla Municipality (Skåne County), Petersborg (Östergötland County) and Örebro (Örebro County). A practical solution is presented that includes the evaluation of strength properties of various types of soil using ordinary Portland cement (OPC), slaked lime and steel slag as pure agents and blended binders. The specimens were collected in Southern Sweden and included sandy silty tills and clay till (clay content 6–18%). The preprocessing included the mineralogical analysis of mineral composition and soil structure by X-ray diffraction (XRD) and a sieve. The soil samples were fabricated, compacted, rammed, stabilised by six binder blends and assessed for uniaxial compressive strength (UCS). The moisture condition value (MCV) and water content tests were done for compacted soil and showed variation in the MCV values for different binders. The study determined the effects from binder blends on the UCS gain in three types of soil, measured on days 7, 28 and 90. Positive effects were noted from the steel slag/lime blends on the UCS gain in sandy silty tills. A steel slag/slaked lime mixed binder performed better compared to the pure binders. The effectiveness of the simplex lattice design was demonstrated in a series of ternary diagrams showing soil strength evaluated by adding the stabilising agents in different proportions., SCOPUS: ar.j, SCOPUS: ar.j, info:eu-repo/semantics/published

More than 600 000 000 tons of slag are generated globally every year, leading to multiple environmental issues. Thus, research on applications of slags is crucial. The use of steel slag in cement is limited by its low hydraulic activity and volumetric instability. In the current study, a clinker-free steel slag binder (SSB) is presented and the coupled alkali–sulfate activation mechanism is discussed. The free-CaO was consumed during hydration, thus minimising the expansion risk. SSB hydration products demonstrated a higher quantity and quality compared with cement, indicating excellent performance. The SSB was tested in a practical mine backfill application, investigating the effects of binder content, concentration, and aggregate grain size on the mechanical and rheological properties of the backfilling mixtures. The results demonstrate the ability of SSB to completely replace Portland cement with half the binder content dose without affecting the strength or flowability of the backfilling mixtures., More than 600 000 000 tons of slag are generated globally every year, leading to multiple environmental issues. Thus, research on applications of slags is crucial. The use of steel slag in cement is limited by its low hydraulic activity and volumetric instability. In the current study, a clinker-free steel slag binder (SSB) is presented and the coupled alkali–sulfate activation mechanism is discussed. The free-CaO was consumed during hydration, thus minimising the expansion risk. SSB hydration products demonstrated a higher quantity and quality compared with cement, indicating excellent performance. The SSB was tested in a practical mine backfill application, investigating the effects of binder content, concentration, and aggregate grain size on the mechanical and rheological properties of the backfilling mixtures. The results demonstrate the ability of SSB to completely replace Portland cement with half the binder content dose without affecting the strength or flowability of the backfilling mixtures.

The purpose of this study is to investigate the adsorption characteristics of granular aggregates under identical experimental conditions for potential applications in highly adsorptive concrete. In this study, industrial by-products (steel slag), lightweight aggregates (expanded silica) and bio-materials (peach shell and miscanthus) are used for phosphorus (P) removal from aqueous solutions. The effects of several parameters such as the initial concentrations of P, reaction time and pH value on adsorption capacity and efficiency of P are investigated using an IC analyzer. Results show that the phosphorus adsorption of all absorbents follows the adsorption isotherms with a varying phosphorus concentration from 5 mg/L to 700 mg/L, and the adsorption isotherms data are fitted well by Langmuir equation. The steel slag exhibits a higher P-adsorption capacity and adsorption efficiency compared to lightweight aggregates and bio-materials, with an estimated maximum adsorption capacity by steel slag of 20.4 mg/g. Moreover, the P-desorption results show that steel slag has a very low P-desorption. Heat treatment is used to increase the adsorption capacity of the miscanthus owing to the change in pore structure characteristics determined by BET. The adsorption kinetic data of the steel slag follows a pseudo-second-order model. The ICP-AES, XRD and SEM-EDS analyses show that the P-adsorption of the miscanthus and peach shell follows physical adsorption, whereas the adsorption mechanism of the steel slag can be attributed to the Ca2+ released from the steel slag, which can react with P and form a stable Ca–P precipitate. It is suggested that steel slags can function as effective adsorptive aggregate for the manufacture of highly adsorptive concrete.

Las industrias siderúrgica y metalúrgica generan grandes cantidades de residuos en forma de escorias de diversa naturaleza procedentes de la fabricación del acero. Aunque se reaprovechan principalmente en la obtención de cemento y como relleno en la estabilización de suelos, aún hay grandes cantidades que acaban depositados en vertederos, con el consiguiente deterioro medioambiental. Esta Tesis Doctoral estudia la valorización de escorias para la fabricación de productos en base yeso en masa o como prefabricados, planteando nuevas formas de producción con estos residuos como materia prima. Se lleva a cabo un estudio comparativo de las propiedades que presentan los yesos con cargas minerales procedentes de los residuos generados en la fabricación del acero, en concreto la escoria negra de Horno Eléctrico de Arco EAF generada en la Metalurgia Primaria, y la escoria blanca de Horno Cuchara LF de los procesos de afino, en comparación con las de los yesos tradicionales. Con el objetivo de mejorar las propiedades de los productos finales, se analiza el efecto de dos aditivos, un superfluidificante para reducir la absorción de agua (SikaMix®) y una emulsión polimérica para mejorar la adherencia superficial (SikaLatex®)., The steel and metallurgical industries generate large amounts of waste as different slags. Even though these slags are mainly recycled in the production of cement and as fillers in the stabilization of soils, there are still large amounts deposited in landfills, with the ensuing environmental impact. This Doctoral Thesis studies the recovery of slag for the fabrication of products based on plaster matrix and as prefabricated, suggesting new forms of construction with this waste as raw material. A comparative study is carried out on the properties of gypsum with mineral fillers from the waste generated in the production of steel, in particular the black slag of Electric Arc Furnace “EAF” generated in Primary Metallurgy, and white slag “LF” from refining processes, in comparison with traditional plaster. Seeking to improve the properties of the final materials, the effect of two additives is deeper analyzed, a super-fluidizer to reduce water absorption (SikaMix®), and a polymer emulsion to improve surface adhesion (SikaLatex®).

Steel slag is being used worldwide for a variety of applications, among which is underwater dyke reinforcement. In the present study the leaching and bioaccumulation of 18 inorganic compounds from basic oxygen furnace (BOF) steel slag were monitored in marine experimental ecosystems (mesocosms) for 12 wk. Triplicate mesocosms were installed at 2 refreshment rates, one reflecting the situation in the Oosterschelde estuary where BOF steel slag was applied and the other at a 35 times lower rate. Vanadium in both water and biota turned out to be the best tracer for the presence of BOF steel slag in the mesocosms. The mesocosm data helped to interpret the results of a 4-yr field sampling program in the Oosterschelde estuary where no elevated levels of vanadium in water or biota were found near locations where steel slag was applied. Also, no ecological impact could be established in the field, which was in line with the observations in the mesocosms. The present study shows the added value of a tailor-made mesocosm study for realistic risk assessment and provides support for applying this tool as a basis for designing efficient field monitoring programs. Environ Toxicol Chem 2021;00:1–11.

The motivation of this work is driven by the feasible hydrogen production, through the reaction between iron-bearing phases, i.e. RO phase, metallic Fe in steel slag and steam. The RO phase can be regarded as (Mn,Mg,Ca)xFe1-xO wüstite that divalent iron is partially substituted by foreign cations of magnesium, manganese and calcium. The reaction behavior in terms of hydrogen generation variation in the temperature range of 500–1000 °C has been studied. It was found that the hydrogen production rate was strongly temperature dependent. Under isothermal conditions, the steel slag-steam reaction proceeded rapidly during the first 2000s. Beyond this, the rate of the reaction decreased significantly due to the formation of (Mg,Mn,Ca)yFe3-yO4 ferrite layer. The theoretical hydrogen generation capacity for steel slag was found to be proportional to the substitution level of foreign cations, i.e. Mg, Mn, Ca in wüstite. The underlying phase transitions, as well as the structural changes were discussed in detail by combing the XRD, SEM-EDS, XPS and VSM analysis. The kinetics analysis showed that the slag-steam reaction agreed well with the three-dimensional diffusion (D3) model and the corresponding activation energy for diffusion was estimated as 105.76 kJ/mol. Moreover, it was noticed that the magnetic properties of steel slag after steam oxidation was greatly enhanced, and the maximum specific magnetic susceptibility was 1.8E-4 m3/kg at 800 °C. This demonstrated steam oxidation could significantly improve the magnetism of steel slag and provide the possibility of iron recovering through magnetic separation. Based on the findings, the novel concept of the steam modification process towards highly efficient utilization of steel slag along its cooling path was proposed. It allowed us to envision the potentials that implementing management of energy production, iron recovery, and volumetric stabilization., QC 20200322

With this study, the removal mechanisms of arsenate by steel slag and its potential for treatment of contaminated water were elucidated. While original slag showed a poor fit to the Langmuir equation (R-2= 0.960), washed slag (the original slag is washed by low pH water solutions to remove readily soluble oxides) conformed better (R-2= 0.995). An initial pH of 2.0 give optimal adsorption, with a strong impact from the chemical speciation observed with highest efficiency for the fully protonated (OH)(3)AsO form. Adsorption capacity of the slag is 4.0 mg g(-1), while together with precipitation the retention capacity reaches 13.7 mg g-1. However, removal by precipitation is a non-steady process due to re-dissolution of Ca-3(AsO4)(2)(s). The washed slag shows a similar adsorption capacity to the original one but has not as strong alkaline properties. Batch experiment shows fast adsorption kinetics and column loading tests indicate an instant adsorption kinetics with 80 % As(V) removal for a 10mgL(-1) As(V) solution by 1.0 g of washed slag using a solution flowrate of 1 mL min(-1). Common ions like sulfate, carbonate, chloride, iron(III), humic acid and fulvic acid do not significantly interfere with the removal efficiency. In combination with limited hazardous metals leaching, the slag is thus appropriate for use as a filter material for treatment of contaminated water and it has been successfully applied as filter material for treatment of arsenate spiked natural water sample with average removal efficiency of 84 % (solid to liquid ratio of 200).

Two adsorbents, pristine electric arc furnace slag (EAFS) and alkali activated slag (AAS) were used for Cu2+ removal from aquatic solutions. Batch adsorption tests were conducted at various temperatures and initial Cu2+ concentrations, while solid to liquid ratio and pH of solution were kept constant. Pseudo-first-order and pseudo-second-order (PSO) kinetics models, Langmuir and Freundlich isotherm models, as well as intraparticle and Boyd's diffusion models were applied in order to investigate the adsorption process. It has been found that alkali activation of EAFS leads to an increase in the specific surface of slag and thus improves the sorption properties of EAFS. The adsorption of Cu2+ onto both adsorbents proceeds via PSO adsorption mechanism, film diffusion mainly controls the adsorption process, and Langmuir isotherm model fits well the experimental data. Results indicated a fast adsorption process which is spontaneous and endothermic in nature. Microstructural investigation of EAFS and AAS revealed morphological changes in metal loaded EAFS and AAS samples in comparison to unloaded adsorbents. X-ray powder diffraction analysis indicated that adsorption of Cu2+ onto both adsorbents occurs through formation of a Cu-complex.

In view of increasing social and environmental consciousness, a circular approach in waste materials management in order to convert them into new secondary resources is becoming more necessary. Given this context, an interlaboratory testing program (ILTP) focusing on maximizing the use of waste aggregates replacing conventional virgin ones has been launched in the framework of the RILEM Technical Committee on “Valorisation of Waste and Secondary Materials for Roads”. Construction and demolition wastes, recycled concrete aggregates and steel slags were selected as waste aggregates to be investigated. A reference mixture prepared with natural virgin aggregates was al-so considered for comparison purposes. This paper describes the results achieved during the first steps of the ILTP concerning: i) the basic characterization of the selected marginal aggregates; ii) the Marshall mix design of different asphalt mixtures prepared with one or more waste aggregates. Overall, the experimental results collected during these preliminary steps seem to confirm that the selected marginal aggregates can be considered as valid alternatives for the traditional road materials, while not jeopardizing their performance

Although Iron and steel industry is essential for the development of society, the industry is responsible for a large portion of CO2 emissions. The industry also produces by-products like metallurgical slag in orders of million tons. The slag is alkaline in nature and rich in Ca and Mg oxides. Upon use the oxide interact with atmospheric CO2 and form carbonates, making them unstable. Storing CO2 in the slag would make it more stable, enhances its life cycle and promotes further usage in various applications. CO2 sequestration can be done through carbonation of steel slag. Carbonation of slag can be achieved through direct and indirect carbonation. Direct carbonation is performed either in a gaseous or an aqueous state in a single step. Indirect carbonation involves multiple steps as it activates the Ca/Mg ions in the slag before they interact with CO2. For an industrial process the direct route would be more viable as it involves lesser steps, easier to scale up. Since there are no solvents to activate the Ca/ Mg the cost involved is also less. This thesis focuses on developing an industrial process to sequester CO2 in metallurgical slag. Sequestration through a combination of gaseous and aqueous has been attempted while studying the effect of carbonation time, carbonation temperature and shape of slag used. Carbonation of the slag is performed using CO2 and steam. The results show that carbonation yield increases with carbonation time and decreases with increase in temperature. The effect of the shape of slag used for carbonation was studied by performing carbonation test in a slag pellet. Diffusion plays a significant role in carbonation process. Powdered slag showed higher carbonation yield compared to the pellet. CO2 uptake as high as 53g of CO2/kg of slag at 200 oC for 6 hr has been achieved. The results indicate the possibility for an industrial carbonation process., Även om järn- och stålindustrin är avgörande för samhällets utveckling, är industrin ansvarigför en stor del av koldioxidutsläppen. Industrin producerar också biprodukter som metallurgisk slagg i order på miljoner ton. Slaggen är alkalisk till sin natur och rik på Ca- och Mg-oxider. Vid användning interagerar oxiden med atmosfärisk CO2 och bildar karbonater, vilket gör dem instabila. Att lagra koldioxid i slaggen skulle göra den mer stabil, förbättra livscykeln och främja ytterligare användning i olika applikationer. CO2-bindning kan göras genom kolsyrning av stålslagg. Kolsyrning av slagg kan uppnås genom direkt och indirekt karbonatisering. Direkt karbonatisering utförs antingen i ett gasformigt eller vattenhaltigt tillstånd i ett enda steg. Indirekt kolsyrning involverar flera steg eftersom den aktiverar Ca/Mg-jonerna i slaggen innan de interagerar med CO2. För en industriell process skulle den direkta vägen vara mer livskraftig eftersom den innebär mindre steg, lättare att skala upp. Eftersom det inte finns några lösningsmedel för att aktivera Ca/Mg är kostnaden också mindre. Denna avhandling fokuserar på att utveckla en industriell process för att binda koldioxid i metallurgisk slagg. Sekvestrering genom en kombination av gasformig och vattenhaltig har försökt under undersökning av effekten av kolsyratid, kolsyratemperatur och form av den använda slaggen. Kolsyringen av slaggen utförs med CO2 och ånga. Resultaten visar att karbonatiseringsutbytet ökar med kolsyratiden och minskar med temperaturökningen. Effekten av formen på slagg som användes för karbonatisering studerades genom att utföra karbonatiseringstest i en slaggpellet. Diffusion spelar en viktig roll i karbonatiseringsprocessen. Pulveriserad slagg visade högre karbonatiseringsutbyte jämfört med pelleten. CO2-upptag så högt som 53 g CO2/kg slagg vid 200 oC under 6 timmar har uppnåtts. Resultaten indikerar möjligheten för en industriell karbonatiseringsprocess.

Recently, implementing steel slag ballast has been proposed as an appropriate material to substitute stone ballast. In this regard, one of the technical concerns is the behavior of steel slag ballast in both time and frequency domains that needs to be assessed, properly. Furthermore, the combination of stone ballast and steel slag is unavoidable in steel slag ballasted tracks during track maintenance concerning the limitation of steel slag resources. Therefore, this paper suggests an optimal stone ballast-steel slag (SB-SS) combination regarding the dynamic behavior of five SB-SS combinations as 0%SS, 25%SS, 50%SS, 75%SS and 100%SS by weight of ballast using a finite element method (FEM) model of a 50-meter test track. Moreover, using elasticity modulus and Moher-coulomb parameters obtained via a series of plate load and shear strength tests for each SB-SS combination turns FEM model to be more close to the real test track results. Experimental results show that adding steel slag particles to stone ballast increases elasticity modulus and friction angle of ballast layer resulting in the improvement of mechanical behavior of railway track. Consequently, the maximum deflections and root mean square (RMS) of accelerations decrease by increasing steel slag content. Analyzing free vibration of ballast layer combinations reveals that damping ratios of 100%SS ballast layer is the maximum value as 0.25 followed by 75%SS, 50%SS, 25%SS and 0%SS combinations. Moreover, the dominant frequencies of each ballast layer combinations determine that 0%SS, 25%SS and 50%SS coincides within the track excitation frequency range made by wheel sets, while 75%SS and 100%SS are out of which. Finally, according to all results, 75%SS ballast layer is proposed as the optimal SB-SS combination., Accepted author manuscript, Mechanics and Physics of Structures

La transcription des symboles et des caractères spéciaux utilisés dans la version originale de ce résumé n’a pas été possible en raison de limitations techniques. La version correcte de ce résumé peut être lue en PDF. La carbonatation minérale est une technique en développement permettant de séquestrer le dioxyde de carbone sous forme de carbonates stables et inertes en utilisant des résidus industriels/miniers alcalins. Le présent projet s’intéresse au développement d’un procédé de captage du CO2 par les scories d’acier. L’objectif de cette étude est d’adopter des conditions opératoires modérées permettant une future application industrielle du procédé. Tout au long du projet, un gaz composé de 10 % v/v CO2 a été utilisé. Deux mélanges de scories provenant de deux aciéries québécoises ont été étudiés. La réaction a été étudiée dans un premier temps en mode discontinu où la température et le temps de la réaction ainsi que la masse du CO2 introduite ont été optimisées. Les meilleures conditions ont été ajustées par la suite pour opérer en mode semi-continu. Les rendements obtenus de 119,73 ± 5,99 gCO2/kgscories et 127,44 ± 2,14 gCO2/kgscories sont comparables aux résultats des travaux antérieurs. Les mêmes conditions ont été testées dans un réacteur à l’échelle pilote pour évaluer l’effet de la mise à échelle du procédé. Aucune différence significative n’a été observée en comparant les résultats de carbonatation à l’échelle laboratoire et pilote. Une modélisation a été établie sur Aspen Plus afin d’optimiser énergétiquement les procédés développés. Cette étape a permis d’éliminer les besoins énergétiques relatifs au chauffage de la réaction par récupération de la chaleur à partir des gaz industriels. Enfin, une étude économique a été menée. Les résultats de cette étude ont montré que la rentabilité des procédés développés dépend principalement de la capacité d’usine et du prix de vente de scories carbonatées. The symbols and special characters used in the

Dredged soils have been used as construction materials by alkaline activation with steel slag (steel slag-dredged soil mixtures) at harbors. Such mixtures develop strength chiefly by calcium silicate hydrate (C-S-H) formation by the pozzolanic reaction. However, the strength of such mixtures is unpredictable, and in some cases, mixtures have been too soft for the intended engineering application. An identification of strength development indicators would accelerate evaluation processes for strength development to facilitate and promote the utilization of such materials. This paper focuses on the relationship between the characteristics of soil organic matters in dredged soils and the strength development of the mixtures by a comparison of eight dredged soils collected from eight different Japanese harbors. The characteristics of the soil organic matters were identified to determine as indicators of mixtures with weak strength development, i.e., enriched sulfur content in extracted soil organic matter (humic acid) fraction, and the N/C ratio of humic acid similar to land humic acid standards. Increases in the validated fraction of dredged soils and steel slag by replacing fractions disadvantageous to construction resources would contribute to reduce waste production, which would lower the environmental impact of the use, aiming to achieve sustainable utilization of such materials.

The aim of this research was to investigate zinc removal from submerged arc furnace flue gas wash water with steel slag and polymer treatment. The current treatment for the submerged arc furnace flue gas wash water is treatment with polymer only which aids in the settling of particulate zinc. However, in this research enhanced removal of zinc by also precipitating soluble zinc using steel slag was studied. The zinc removal results were compared with the results using commercial neutralizing agents NaOH, Mg(OH)₂, and Ca(OH)₂ together with polymer. The precipitation conditions were simulated with MINEQL + software and the calculated results were compared with the results from laboratory jar test experiments. Zinc was removed to less than the target concentration 2 mg/l with steel slag and polymer treatment at pH 9. Additionally, turbidity of the treated water decreased to 20 NTU compared to the initial 860 NTU. However, the amount of steel slag needed in the treatment was significantly higher than the amounts of NaOH and Ca(OH)₂. The main zinc removal mechanism of steel slag was precipitation as zinc oxide. Calculated zinc removal was higher than the experimental which indicates that equilibrium was not reached in the precipitation experiments which could be due to relatively short contact time chosen to simulate the actual process conditions at the plant.

Pristine electric arc furnace slag (EAFS) as well as EAFS modified by alkali activation i.e. alkali activated slag (AAS) have found a novel application as adsorbents used in Cu2+ removal from sulfate solutions. The adsorption tests were carried in batch conditions and results have shown that alkali activation of EAFS enhances the Cu2+ adsorption. The adsorption process was found to follow a pseudo second-order kinetic model and occurs via formation of posnjakite (Cu-4(SO4)(OH)(6)center dot H2O) on the surface of both, EAFS and AAS. Enhanced adsorption properties of AAS, compared to EAFS, are attributed to a more porous structure, larger specific surface area and an increased number of surface groups involved in the binding of Cu2+.

Microwave heating is an encouraging heating technology for the maintenance, recycling, and deicing of asphalt pavement. To investigate the microwave heating properties of asphalt mixture, laboratory tests and numerical simulations were done and compared. Two types of Stone Mastic Asphalt (SMA) mixture samples (with basalt aggregates and steel slag aggregates) were heated using a microwave oven for different times. Numerical simulation models of microwave heating of asphalt mixture were developed with finite element software COMSOL Multiphysics. The main thermal and electromagnetic properties of asphalt mixture, served as the model input parameters, were measured through a series of laboratory tests. Both laboratory-measured and numerical simulated surface temperatures were recorded and analyzed. Results show that the replacement of basalt aggregates with steel slag aggregates can significantly increase the microwave heating efficiency of asphalt mixture. Numerical simulation results have a good correlation with laboratory test results. It is feasible to use the developed model coupling electromagnetic waves with heat transfer to simulate the microwave heating process of asphalt mixture., Pavement Engineering

The CHROMIC project aims to recover chromium from steelmaking and ferrochrome slags to regain valuable resources and simultaneously reduce potential environmental impacts. To develop the recovery flowsheets, and reliably calculate metal recovery, an accurate assessment of chromium concentration and distribution is essential. Therefore, model streams were thoroughly characterized using a combination of analytical techniques . In all materials, chromium is present in distinct but often small spinel phases, intertwined with other minerals and showing a considerable zonation in Cr-content with higher amounts in the cores. The small size of the Cr-rich particles makes recovery by mineral processing challenging. Measured chromium content was found to differ largely based on the chemical dissolution method applied. Analysis of insoluble residues and comparison with a standard reference material evidenced that standard acid dissolution procedures based on HCl/HNO₃/HBF₄ and HNO₃/HF/H₂O₂ are insufficient to fully dissolve spinel structures, leading to severe underestimations of chromium content. A sodium peroxide treatment is required for a full dissolution of spinel. This is noteworthy since most legislation for reuse of slags are currently based on acid dissolution methods.

Steel slag is a by-product from steel production and has potential to act as a sorbent for several contaminants. Contaminated water is a global problem and cheap and simple remediation solutions are often sought. The potentials are many to use an industrial residue for water purification purposes e.g. low cost. The absorption efficiency was evaluated for two different steel slags further divided into two grain sizes, <0.9 mm and 0.9-2 mm. Laboratory experiments was conducted for three anionic elements; bromine, chromate and molybdate. Controlled parameters were; time, sorbent amount and sorbate concentration. The sorption was primarily dependent on the grain size and the smaller grain size had a higher sorption of all three tested anionic species. Unfortunately the results are partially affected by the release of the tested elements from the sorbent itself.

During production of steel, slag is formed as a by-product. The process of steelmaking involves usage of additives such as chromium or vanadium as reactants to optimize and produce high quality steel. Vast amounts of slag are formed and there is a continuous search for applications that can make good use of the slag. Currently the use of slag in cleaning of metal polluted waters is researched and promising results has been found for many different types of slags. In this work two different AOD-slags has been used as sorbents for some selected elements (Zn, V, Cr, Mo, Pb, Li, Cd, Ba, Cu, Ni). The main difference between the two slags is the reducing agent that has been used, aluminium and silicon. This results in slags with different adsorption properties. The aluminium reduced slag show tendency for better adsorption capacities in general for the tested elements (Zn, V, Cr, Mo, Pb, Li, Cd, Ba, Cu, Ni), with a few exceptions. The buffering capacity of the materials were high, shown by the fact that final pH reached nearly 11.5 independent of the start pH (varied between 2 and 8). The adsorption process was rather quick and 24 minutes contact time was in most cases sufficient to reach equilibrium. For several of the elements e.g. Lithium, the maximum capacity of the slags was not reached even though a load of 3,07 mg Lithium was added per gram of slag.

Electric arc furnace slag (EAFS) is the by-product of steel production in an electric arc furnace. In a pass two decade a special attention is paid to the valorization of metallurgical slags by alkali activation. The process involves a chemical reaction of slag with the alkaline activator followed by the condensation and hardening processes. Aluminium-containing calcium silicate hydrate gel i.e. C–(A)–S–H gel with a low C/S ratio has been identified as a reaction product of slag alkali activation. We have synthesized the AAS using the EAFS as the precursor and Na2SiO3 solution as an activator. The AAS samples are characterized by XRD, SEM/EDS and FTIR analysis. Moreover, investigation of mechanical properties dilatometric and porosity analysis were performed as well so as to build up a detailed illustration of AAS properties and possible application of these materials. The results have shown that AAS may reach the compressive strength (~ 40 MPa) which enables its application in a civil engineering. Moreover, the AAS sample exhibits improved strength (~ 50 MPa) at elevated temperatures thus potential application of these materials in a high temperature conditions should be considered. On the other hand, these materials may be used as an effective adsorbent for the Cu2+ removal from sulfate bearing wastewater. The Cu2 + ions have been found to be attached on the surface of AAS by formation of stable hydrooxocomplexes that are sorbed on the adsorbent surface via hydroxyl groups in the form of posnjakite crystal phase.

The durability of alkali-activated steel electric arc furnace slag (EAFS) in a marine environment was evaluated with respect to the chemical composition of the alkaline activator. Two different alkaline activators have been used: a mixture of NaOH and Na2SiO3 solutions (Na-activator), as well as a mixture of KOH and K2SiO3 solutions (K-activator). The obtained results gave the insight into the influence of alkaline activator chemistry on the compressive strength and durability of alkali-activated slag (AAS), which was exposed to the damaging seawater environment. The porosity of AAS was found to be the most important factor with regards to the strength and durability of these materials in marine environment. Sodium based alkali-activated slag (Na-AAS) displayed lower porosity and higher compressive strength compared to potassium based AAS (K-AAS). Lower porosity and thus a lower rate of water uptake by AAS matrix, i.e., the lower sorptivity was exhibited by the Na-AAS when compared to K-AAS. Hence, Na-AAS exhibited better durability in a marine environment.

In the manufacture of asphalt mixtures, large quantities of natural stone aggregates are consumed, which has a negative impact on the environment. These aggregates can be partially or totally replaced by others that are disposed of in dumps and produced by steel companies, such as blast furnace slag (BFS) and steel (SS). These last two materials have chemical and physical properties that make them suitable for use in multiple applications such as road construction, maintenance and rehabilitation. The article presents a review of the state of knowledge of the use of BFS and SS in the production of asphalt mixtures, describes and defines both materials, presents the environmental problems, their toxicological risk of use, their chemical and physical properties, the advantages and limitations of use and the way they have been studied to be used as stone aggregates of asphalt mixtures. Based on the bibliographic review, the authors at the end of the article present some recommendations to continue the studies tending to substitute natural stone aggregates with BFS and SS in the manufacture of asphalt mixtures., grandes quantidades de agregados pétreos de origem natural são consumidos na fabricação de misturas asfálticas, o que impacta negativamente o ambiente. Esses agregados podem ser substituídos parcial ou totalmente por outros que são descartados em aterros e produzidos pelas companhias siderúrgicas, como as escórias de alto-forno (BFS) e aço (SS). Esses dois últimos materiais apresentam propriedades químicas e físicas que os tornam aptos para serem utilizados em múltiplas aplicações, como a construção, a manutenção e a reabilitação de estradas. No artigo, apresenta-se uma revisão do estado do conhecimento do emprego de BFS e SS na produção de misturas asfálticas, ambos os materiais são descritos e definidos, apresenta-se a problemática ambiental, seu risco toxicológico de uso, suas propriedades químicas e físicas, as vantagens e limitações de uso e a forma como foram estudados para serem empregados como agregados pétreos de misturas asfálticas. Com base na revisão bibliográfica realizada, os autores ao final do artigo expõem algumas recomendações para continuar os estudos com tendência a substituir agregados pétreos naturais por BFS e SS na fabricação de misturas asfálticas., En la fabricación de mezclas asfálticas se consumen grandes cantidades de agregados pétreos de origen natural lo que impacta negativamente el ambiente. Estos agregados pueden ser sustituidos parcial o totalmente por otros que son desechados en escombreras y producidos por las compañías siderúrgicas, como las escorias de alto horno (BFS) y acero (SS). Estos dos últimos materiales poseen propiedades químicas y físicas que los hacen aptos para ser utilizados en múltiples aplicaciones como la construcción, mantenimiento y rehabilitación de carreteras. En el artículo se presenta una revisión del estado del conocimiento del empleo de BFS y SS en la producción de mezclas asfálticas, se describen y definen ambos materiales, se presenta la problemática ambiental, su riesgo toxicológico de uso, sus propiedades químicas y físicas, las ventajas y limitaciones de uso y la forma como han sido estudiados para ser empleados como agregados pétreos de mezclas asfálticas. Con base en la revisión bibliográfica realizada, los autores al final del artículo exponen algunas recomendaciones para continuar los estudios tendientes a sustituir agregados pétreos naturales por BFS y SS en la fabricación de mezclas asfálticas.

Some of the steel slag from ironworks and dredged soils from marine and waterfront engineering work are partially treated as waste. However, a mixture of these two kinds of waste has the potential to be used as construction materials when mixed, due to chemical reactions forming secondary phases. Utilizing waste of such kind as a resource will help to improve sustainability in society by reducing waste and replacing virgin resources such as cement. Recently, it was reported that mixtures of steel slag and dredged soil hardens under specific conditions. The phase compositions of dredged soils and steel slags vary depending on the quantity of each component, which results in unpredictable strength development of mixtures. The effect of the variations in the components of steel slags and dredged soils on strength development of the mixtures is not yet clear, limiting the utilization of both materials. Understanding the hardening mechanisms of the mixtures will enable the prediction of strength development. Focusing on the variations in the components in steel slags and, especially of dredged soils, this study aims to identify the components in both materials that affect the secondary phase formation that are responsible for strength development. We found support for suggestions that calcium silicate hydrate, C-S-H, is one of the secondary phases responsible for the strength development of the mixtures. From a comparison of two kinds of steel slags and various dredged soils, the amount of portlandite in the steel slags and the amount of amorphous silica in the dredged soils are suggested as a couple of the key components of starting materials involved in the C-S-H formation.

This study aimed to evaluate the long term performance of the selected surface friction treatments, including high friction surface treatment (HFST) using calcined bauxite and steel slag, and conventional friction surfacing, in particular pavement preservation treatments such as chip seal, microsurfacing, ultrathin bonded wearing course (UBWC), and diamond grinding. This study also attempted to determine the correlation between vehicle crash and pavement surface friction, which makes it possible to quantitatively establish the so-called crash modification factors (CMFs) that are extremely useful in selecting a cost-effective solution to reduce wet pavement vehicle crashes. In-depth reviews were conducted to identify the aspects of the properties for aggregates used in HFST, including aggregate abrasion value (AAV), Los Angeles abrasion (LAA), Micro-Deval abrasion, and polished stone value (PSV). Extensive laboratory testing was conducted to examine the LAA, Micro-Deval abrasion, and PSV, and to provide first-hand data on the calcined bauxite and steel slag that may be used for HFST and friction surfacing in Indiana. Laboratory accelerating polishing was carried out to evaluate the effect of aggregate gradation and identify the HFST systems with satisfactory friction performance with respect to surface macro-texture and friction. Test strips were installed in the pavement on a real-world road to further evaluate the friction performances of the promising HFST systems under the true traffic polishing and assess the potential effect of winter and snow plough. Pull-off testing was also conducted to examine the bonding between the proposed HFST systems and the substrate surface. Field friction test data was utilized to evaluate the long-term friction performances of pavement preservation treatments, including chip seal, microsurfacing, UBWC, and diamond grinding. Statewide vehicle crash data between 2010 and 2014 was examined to determine the crash statistics associated

The Calcium Looping (CaL) process, based on the carbonation/calcination of CaO, has been proposed as a feasible technology for Thermochemical Energy Storage (TCES) in Concentrated Solar Power (CSP) plants. The CaL process usually employs limestone as CaO precursor for its very low cost, non-toxicity, abundance and wide geographical distribution. However, the multicycle activity of limestone derived CaO under relevant CaL conditions for TCES in CSP plants can be severely limited by pore plugging. In this work, the alternative use of calcium-rich steel and blast furnace slags after treatment with acetic acid is investigated. A main observation is that the calcination temperature to regenerate the CaO is significantly reduced as compared to limestone. Furthermore, the multicycle activity of some of the slags tested at relevant CaL conditions for TCES remains high and stable if the treated samples are subjected to filtration. This process serves to remove silica grains, which helps decrease the porosity of the CaO resulting from calcination in the mesoporous range thus mitigating pore plugging.

In this paper, steel slag/steel fiber composite asphalt mixture were prepared. The effects of the addition of steel slag and/or steel fibers on the mechanical, thermal, induction heating and healing properties of asphalt mixture were investigated. The results showed that adding steel slag and/or steel fibers improves the water stability, particle loss resistance and fracture energy of asphalt mixtures. The addition of steel fibers increased the thermal conductivity and thermal diffusion of the asphalt mixture, and steel slag showed a reverse effect. Steel slag asphalt mixture cooled more slowly than steel fiber asphalt mixture, which is beneficial to crack healing of asphalt mixture. The composite of steel fibers and steel slag can enhance the induction heating speed, heating homogeneity and thus enhance the induction healing ratio of asphalt mixture. It is concluded that steel slag/steel fibers composite asphalt mixture achieves good mechanical and induction healing properties., Materials and Environment

Deep penetration of renewable energies into the grid relies on the development of large-scale energy storage technologies using cheap, abundant, and nontoxic materials. Concentrated solar power (CSP) is particularly suitable to massively store thermal energy for dispatchable electricity generation. This is currently accomplished in a few demonstration plants by using molten salts albeit in a not competitive way yet. Process simulation studies indicate that thermochemical energy storage of CSP by means of the calcium looping (CaL) technology would reduce the cost of storage and increase the flexibility of energy supply provided that widely available and cheap CaO precursors with high and stable multicycle activity are used. In this work, we investigate the behavior of calcium rich steel slag at CaL conditions that would expectedly maximize the efficiency of CSP energy storage and power production. When treated with acetic acid, this nontoxic widely abundant waste yields a CaO rich solid with stable conversion near 0.8 over successive carbonation/calcination cycles at these CaL conditions.

Worldwide the modern society produces vast amounts of waste materials containing strategic and valuable metals. Some of them are of substantial economic or environmental significance if controlled recovery of metals can be performed or if uncontrolled release to the environment occurs. By cultivating Agrostis capillaris on historical sulfidic mine waste the leachate composition can be altered and its volume reduced. In combination with additives such as bark compost and water works granules the concentration of several hazardous metals decreased significantly already after eight weeks. Limited actions can therefore be used to decrease the environmental impact from such waste. Shale in general contains considerable amounts of strategic metals. If naturally occurring microorganisms are provided with a source of nutrients, increased mobilization of strategic metals can be obtained. By using wood chips as the nutrient source the mobilization of vanadium and uranium increased significantly. Highest mobilization efficiency was observed when the carbon source was put on top of the shale. Analysis of strategic metals is often performed by argon plasma techniques such as ICP-QMS. However, the use of argon increases the analytical costs. If isotopic information is not needed and slightly higher uncertainties can be accepted, several strategic metals can successfully be quantified by the nitrogen plasma based MP AES. The analytical cost can then be cut with more than 99%.

The Calcium Looping (CaL) process, based on the carbonation/calcination of CaO, has been proposed as a feasible technology for Thermochemical Energy Storage (TCES) in Concentrated Solar Power (CSP) plants. The CaL process usually employs limestone as CaO precursor for its very low cost, non-toxicity, abundance and wide geographical distribution. However, the multicycle activity of limestone derived CaO under relevant CaL conditions for TCES in CSP plants can be severely limited by pore plugging. In this work, the alternative use of calcium-rich steel and blast furnace slags after treatment with acetic acid is investigated. A main observation is that the calcination temperature to regenerate the CaO is significantly reduced as compared to limestone. Furthermore, the multicycle activity of some of the slags tested at relevant CaL conditions for TCES remains high and stable if the treated samples are subjected to filtration. This process serves to remove silica grains, which helps decrease the porosity of the CaO resulting from calcination in the mesoporous range thus mitigating pore plugging.

Deep penetration of renewable energies into the grid relies on the development of large-scale energy storage technologies using cheap, abundant, and nontoxic materials. Concentrated solar power (CSP) is particularly suitable to massively store thermal energy for dispatchable electricity generation. This is currently accomplished in a few demonstration plants by using molten salts albeit in a not competitive way yet. Process simulation studies indicate that thermochemical energy storage of CSP by means of the calcium looping (CaL) technology would reduce the cost of storage and increase the flexibility of energy supply provided that widely available and cheap CaO precursors with high and stable multicycle activity are used. In this work, we investigate the behavior of calcium rich steel slag at CaL conditions that would expectedly maximize the efficiency of CSP energy storage and power production. When treated with acetic acid, this nontoxic widely abundant waste yields a CaO rich solid with stable conversion near 0.8 over successive carbonation/calcination cycles at these CaL conditions.

In this study, the thermodynamics of a novel strategy, i.e., biomass/CO2 gasification integrated with heat recovery from hot slags in the steel industry, were systemically investigated. Both the target syngas yield and the polluting gas release were considered where the effect of gasifying conditions including temperature, pressure and CO2 reacted was analyzed and then the roles of hot slags were further clarified. The results indicated that there existed an optimum temperature for the maximization of H2 production. Compared to blast furnace slags, steel slags remarkably increased the CO yield at 600–1400 °C due to the existence of iron oxides and decreased the S-containing gas releases at 400–700 °C, indicating potential desulfurizing ability. The identification of biomass/CO2 gasification thermodynamics in presence of slags could thus provide important clues not only for the deep understanding of biomass gasification but also for the industrial application of this emerging strategy from the viewpoint of syngas optimization and pollution control., QC 20161117

Geopolymeric binders (GB) were produced using fly ash (FA) and electric arc furnace slag (EAFS). The slag has been added in the range of 0–40%. The effects of slag content on the strength, microstructure and thermal resistance were evaluated. It was found that the amount of EAFS up to 30% positively affects the strength evolution of GB. The main reaction product of FA/EAFS blends was amorphous N–(C)–A–S–H gel along with geopolymer-type gel (N–A–S–H). Thermal resistance of GB was considered from the standpoint of their mechanical and dimensional stability after heating in the temperature interval of 600–800 °C. The changes in mechanical and thermal properties of GB after heating are attributed to the changes in their structure. The results have shown that EAFS negatively affects the thermal resistance of GB above 600 °C due to the phase transition and morphological transformation of the amorphous gel phase.