The type of steel furnace slag (SFS), including electric arc furnace (EAF) slag, basic oxygen furnace (BOF) slag, ladle metallurgy furnace (LMF) slag, and argon oxygen decarburization (AOD) slag, can ...significantly affect the composite properties when used as an aggregate or as a supplementary cementitious material in bound applications, such as concretes, mortars, alkali-activated materials, and stabilized soils. This review seeks to collate the findings from the literature to express the variability in material properties and to attempt to explain the source(s) of the variability. It was found that SFS composition and properties can be highly variable, including different compositions on the exterior and interior of a given SFS particle, which can affect bonding conditions and be one source of variability on composite properties. A suite of tests is proposed to better assess a given SFS stock for potential use in bound applications; at a minimum, the SFS should be evaluated for free CaO content, expansion potential, mineralogical composition, cementitious composite mechanical properties, and chemical composition with secondary tests, including cementitious composite durability properties, microstructural characterization, and free MgO content.
Water quenched blast furnace slag is an excellent hydrated material. However, dry granulation is a new treatment method for molten blast furnace slag that has numerous advantages compared to water ...quenching. This study investigated the size distribution of slag particles obtained from the dry granulation of molten slag. In addition, the effect of using the slag obtained from dry granulation in slag cement blends was analyzed. All the results showed that there was a wide size distribution range of blast furnace slag particles in ligament formation. The mean diameter of the solid particles decreased as the rotating speed increased. Meanwhile, the glass content in slag particles decreased for a fixed diameter of the metal collecting tray. The strength of slag cement concrete was low at a low rotating speed. In contrast, obtaining slag particles at a high rotating speed was beneficial for producing a compact structure in the slag cement blend.
Display omitted
•The mean diameter of solid particles decreased with an increase in rotating speed.•It is easy to form compact structure in slag cement at high rotating speed.•The strength of slag cement was determined by slag powder size distribution.
Steel is a critical material in our societies and will remain an important one for a long time into the future. In the last two decades, the world steel industry has gone through drastic changes and ...this is predicted to continue in the future. The Asian countries (e.g. China, India) have been dominant in the production of steel creating global over-capacity, while the steel industry in the developed countries have made tremendous efforts to reinforce its global leadership in process technology and product development, and remain sustainable and competitive. The global steel industry is also facing various grand challenges in strict environmental regulation, new energy and materials sources, and ever-increasing customer requirements for high quality steel products, which has been addressed accordingly by the global iron and steel community.
This Special Issue, “Ironmaking and Steelmaking”, released by the journal Metals, published 33 high quality articles from the international iron and steel community, covering the state-of-the-art of the ironmaking and steelmaking processes. This includes fundamental understanding, experimental investigation, pilot plant trials, industrial applications and big data utilization in the improvement and optimization of existing processes, and research and development in transformative technologies. It is hoped that the creation of this special issue as a scientific platform will help drive the iron and steel community to build a sustainable steel industry.
•The characterization, applications, and performance of steel slag are addressed.•An approach of hardness and grindability is presented.•Expansive characteristics of steel slag and mitigation ...mechanisms are discussed.•Presence of toxic elements (Cr, Ni, V) is treated in environmental classification.•Durability parameters of cement-based composites with steel slag are portrayed.
Steel slags are by-products generated in high volumes in the steel industry. Their main constituents are calcium, silicon, ferric, aluminum, and magnesium oxides. Larnite, alite, brownmillerite, and ferrite are also found. The presence of expansive compounds cause concern when used in cement-based composites; however, mitigating routes have been proposed. Activation techniques improve the binding properties of steel slag powder, potentiating its use as a supplementary cementitious material (SCM). As an aggregate, steel slag presents good morphological and mechanical properties. Promising mechanical and durability performances in cement-based composites encourage further research to promote the use of steel slag.
As previous studies of mortar and concrete with steel furnace slag (SFS) aggregates have shown increases or decreases in the bulk mechanical properties, this study investigated the microstructural ...cause of these opposing trends through characterization of the interfacial transition zone (ITZ) with quantitative image analysis of backscatter electron micrographs. Three SFS types – basic oxygen furnace (BOF), electric arc furnace (EAF), EAF/ladle metallurgy furnace (EAF/LMF) – were examined as aggregates in a portland cement mortar. The ITZ size for all SFS mortar mixtures was similar, with the ITZ of BOF and EAF/LMF being slightly more porous than mortar mixtures with EAF or dolomite. Microstructural examinations of the SFS particle revealed that BOF and EAF/LMF aggregates have different outer and interior compositions, with the outer composition consisting of a porous layer, which likely contributes to the reduced strength relative to EAF. The imaging results demonstrated that the type of SFS and its spatial composition greatly influences the bulk properties of mortar and concrete, mainly as a function of porosity content in the ITZ and the outer layer and interior porosity of the SFS aggregate.
The interfacial adhesion between asphalt and steel slag aggregate is a decisive factor in the formation of an asphalt-steel slag mixture and significantly affects the quality stability of steel ...slag-asphalt mixtures. In this study, the adhesion between an asphalt and steel slag aggregate, the interfacial microstructure, the adsorption and desorption characteristics, and chemical reactions were, respectively, explored by a PosiTestAT-A adhesion puller, a scanning electron microscope, a net adsorption test, an infrared spectrometer, and a dynamic shear rheometer. The mechanism of adhesion between the asphalt and steel slag aggregate was analyzed from the perspectives of physical adsorption and chemical reactions. The results showed that different factors had different effects on the adhesion of asphalt-steel slag aggregate interface. The freeze-thaw cycle and steel slag aggregate particle size had significant effects on interfacial adhesion, while the asphalt heating temperature, water bath time, and stirring time had relatively weak effects on interfacial adhesion. Compared to a limestone aggregate, the steel slag-asphalt mixture had greater adhesion and better adhesion performance because the pits and textures on the surface of the steel slag aggregate produced a skeleton-like effect that strengthened the phase strength of the asphalt-slag aggregate interface, thereby improving the adhesion and increasing the physical adsorption between the asphalt and steel slag aggregate. In addition, due to the N-H stretching vibrations of the amines and amides, as well as SiO-H stretching vibrations, a chemical reaction occurred between the asphalt and steel slag aggregate, thus improving the adhesion performance between the asphalt and steel slag. Based on the shape of the adsorption isotherm, it was determined that the adsorption type was multi-molecular layer adsorption, indicating that the adhesion between the asphalt and steel slag mainly involved physical adsorption.
This paper reviews the potential use of silico-manganese slag (SiMnS) as binder and aggregate in Portland cement and geopolymer concrete. SiMnS is a byproduct of alloy steel production. Depending on ...the process of solidification, the slag is available in crystalline hard stone type and granulated glassy form. The latter one is more reactive due to the presence of amorphous phases. Therefore, granulated slag has been mostly used as supplementary cementitious material, either blending with clinker or as a precursor for alkali activated binder. Whereas the former is less reactive, and has been mostly used as aggregate, which can enhance the properties of the concrete. The reactive component such as CaO and SiO2 improve the binding capability of the cement gel. The leaching of toxic and heavy metals from the SiMnS reacted binder matrix is not reported. This paper also highlights the future potential of this slag by a process called slag engineering to modify its chemistry similar to granulated blast furnace slag (GBFS), to be utilized more effectively.
Display omitted
Metallurgical slag as a by-product of the metallurgical industry not only has huge storage capacity and low price, but also causes serious damage to the environment and threatens the safety of human ...life by heavy metal in metallurgical slag leaching. The approach of metallurgical slag used to remove pollutants in wastewater is considered to achieve the purpose of “using waste to treat waste”. This review focuses on three pretreatment methods of metallurgical slag including acid/alkali pretreatment, mixed pretreatment, and core-shell structure pretreatment, and their structural properties and performance optimization after pretreatment. The removal mechanism of typical pollutants, catalytic performance, reaction conditions, and recyclability of metallurgical slag such as steel slag, blast furnace slag, red mud, copper slag, and manganese slag are summarized and compared.
Display omitted
•Application of metallurgical slag in the wastewater treatment is summarized.•Three pretreatment methods of metallurgical slag are introduced.•Structure and performance of pretreated metallurgical slag are compared.•The removal mechanisms and influencing factors are introduced.•Sustainable utilization of metallurgical slag is discussed.
Autogenous shrinkage of alkali-activated slag cement (AASC) paste prepared with different levels of alkali dosage and silicate modulus (Ms) is investigated. The results show that autogenous shrinkage ...of AASC paste increases at a decreasing rate with alkali dosage, which is attributed to enhanced capillary pore pressure and syneresis of C-A-S-H gels. Autogenous shrinkage of AASC paste with a constant alkali dosage increases as Ms increases from 0.5 to 1.0, followed with a reduction as Ms further increases to 2.0. Increasing Ms initially enhances the capillary pore pressure due to the enhanced reaction degree, and promotes the formation of saturated capillary pores and viscoelasticity, which facilitates the autogenous shrinkage of AASC paste. However, excessive silicate in the activator retards the internal moisture consumption, and subsequently decreases the autogenous shrinkage of AASC paste. Furthermore, increasing Ms can also intensify syneresis of C-A-S-H gels, contributing to the early-age autogenous shrinkage of AASC paste.
Concrete is the most produced construction material in the world and has a close tie to carbon dioxide emissions. To reduce the gas pollution and resource drain of cement production and utilization, ...researchers have replaced some of the cement and natural aggregate content with industrial by-products such as steel slag, ferronickel slag, copper tailings, and copper slag. However, a comparison of these widely used by-products in the construction industry, especially in the environmental health aspect, has not been discussed. This paper examines and compares these four by-products critically, with a particular emphasis on their chemical compositions, performance in concrete, and environmental suitability as construction materials. Generally, these industrial wastes can be used to increase specific mechanical properties of the concrete when used as a partial cement and fine aggregate replacement. The environmental concerns were evaluated by looking at leaching test data, finding most studies reporting leached heavy metal contents below specific standards. This paper's comprehensive review and analysis can be considered for practical use. The paper also addresses gaps in different slags (e.g., steel and copper slag) and copper waste (e.g., copper slag and tailing), and future research opportunities for using metal production by-products.
Display omitted
PDF
