Steel slags are industrial by-products of steel manufacturing, characterized as highly calcareous, siliceous and ferrous. They can be categorized into basic oxygen furnace (BOF) slag, electric arc furnace (EAF) slag, and ladle furnace (LF) slag. They are found to be useful in many fields, such as road construction, asphalt concrete, agricultural fertilizer, and soil improvement. However, better utilization for value-added purposes in cement and concrete products can be achieved. In this paper, an overview of the recent achievements and challenges of using steel slags (BOF, EAF and LF slag) as cement replacement (usually ground into powder form with the size of 400–500 m2/kg) and aggregate in cement concrete is presented. The results suggest that the cementitious ability of all steel slags in concrete is low and requires activation. For the incorporation of steel slags as aggregate in concrete, special attention needs to be paid due to the potential volumetric instability associated with the hydration of free CaO and/or MgO in the slags. Studies have indicated that adequate aging/weathering and treatments can enhance the hydrolyses of free-CaO and -MgO to mitigate the instability. Considering the environmental and economic aspects, steel slags are also considered to have a potential use as the raw meal in cement clinker production.

Characteristics of steel slags and their use in cement and concrete—A review

Supplementary cementitious materials: New sources, characterization, and performance insights

Plant proteins gain increasing interest as part of a sustainable diet. Because plant materials not only contain protein, they are generally isolated via an energy intensive wet fractionation. This review discusses dry fractionation as an alternative and more sustainable route for producing functional legume protein-enriched fractions. Increasing protein purity of dry-enriched fractions is discussed by identification of relationships between legume morphology and ability for separation in the dry state. Finally, functionality and nutritional properties of legume protein fractions and their application in high protein beverage and meat like structures are reviewed.

Dry fractionation for sustainable production of functional legume protein concentrates

Steel slag is a by-product discharged from the steelmaking process, which is characterized by abundant free calcium/magnesium oxide, low cementitious properties, and high contents of heavy metals. The disposal of steel slag at landfills not only wastes valuable resources but also causes serious pollutions to the environment. However, the direct use of untreated steel slag poses a great risk to the mechanical properties and durability of the steel slag-derived composites. In recent years, research on the use of steel slag as eco-friendly construction materials has experienced an unprecedented advance, particularly with the discovery that accelerated carbonation is conducive to improving the inferior properties. This review summarizes the various types of steel slags based on chemical/mineral compositions and the related physic-chemical properties. It also highlights recent progress on the use of accelerated carbonation to improve the quality of steel slag in the context of a wide range of influencing factors, such as temperature, reaction time, CO2 concentration and pressure, moisture, particle size and gradation of steel slag, and additives. A major challenge is to dissect the interconnectedness between the influencing factors and their relative contributions to the property improvement of steel slag. After that, we introduce the practical applications of carbonated steel slag with improved properties. Finally, we provide new insights into the mechanisms and challenges of using accelerated carbonation as a treatment of steel slag for future research and industrial applications.

Use of steel slag as sustainable construction materials: A review of accelerated carbonation treatment

Accelerated carbonation curing of cement mortars containing cement kiln dust: An effective way of CO2 sequestration and carbon footprint reduction

Simulation and property prediction of MgO-FeO-MnO solid solution in steel slag

Design of a new double layer spreading plate for a turbo air classifier

The low hydration activity and volumetric instability of steel slag (SS) limits its application as a binding material. SS contains approximately 30 pct of a divalent metal oxide solid solution (RO phase). According to the XRD results of the RO phase extracted from SS, RO phases (MgO·xFeO) with different compositions were synthesized to study their hydration activity and expansibility. The hydration activity of the RO phase was found to exponentially decrease with the increasing molar ratio (x) of FeO to MgO in the RO phase. When x ≥ 1 .5, the RO phase could not be hydrated after autoclaving at 215 °C and 2 MPa for 3 hours. The RO phase was blended into cement to study the relationships among the expansibility and composition and content of the RO phase via an autoclave test. When x ≤0.5, more than 5 pct of the RO phase cracked the specimen. When 0.5 < x < 1.5, the autoclave expansion rate of the specimen decreased with the increasing value of x in the RO phase. When x ≥ 1.5, the autoclave expansion rate of the specimen linearly increased with the content of the RO phase and was independent of the composition of the RO phase.

Jiaxiang Liu

Papers

Simulation and property prediction of MgO-FeO-MnO solid solution in steel slag

Design of a new double layer spreading plate for a turbo air classifier

Hydration Activity and Expansibility Model for the RO Phase in Steel Slag

A new volute design method for the turbo air classifier

Enhancing indium tin oxide (ITO) thin film adhesiveness using the coupling agent silane