ReviewCharacteristics of steel slags and their use in cement and concrete—A review
Introduction
Recently, the green supply chain (e.g., waste-to-resources) has been aggressively established in industrial parks around the world to realize a circular economy (Li et al., 2015). Steel slags, industrial by-products of steel manufacturing, are annually produced in a huge quantity, which should be considered as a green resource. Modern steels can be broadly categorized into four types, i.e., carbon, alloy, stainless and tool steels. Carbon steel is produced either in a basic oxygen furnace (BOF) or an electric arc furnace (EAF), and then refined in a ladle furnace (LF) to achieve a better quality. As for stainless steel, it can be produced in an EAF, an LF, or an argon oxygen decarburization (AOD) furnace (Iacobescu et al., 2016; Kriskova et al., 2012; Zhang and Xin, 2011). During the manufacturing of carbon and stainless steels, a significant amount of by-product steel-slag is produced, accounting for about 15–20 wt.% of the total steel output (Han et al., 2015; Shi, 2004). The compositions of the generated steel slags are highly variable and basically, they can be classified into BOF slag, EAF slag and LF slag.
The annual production of steel slags is about 14 million tons in Japan (NSA, 2017), 21 million tons in Europe (Euroslag, 2012) and over a hundred million tons in China (Zhang et al., 2011). Compared with the widespread use of blast furnace slag, steel slags undergo less upgrading since they usually encounter several technological barriers to valorization such as volume instability (Pan et al., 2016). More than 400 million tons of steel slags have been deposited in China, with an annual accumulation rate of 100 million tons, leading to occupation of lands and potential pollution of water and soil due to the alkaline leachates from steel slags (Mayes et al., 2008; Shi and Qian, 2000; Zhang et al., 2011). Currently, steel slags can be recycled for internal metallurgical purposes (Yi et al., 2012) or used in road construction (Pasetto and Baldo, 2010a,b, 2015, 2016), cement and concrete (Carvalho et al., 2017; Yi et al., 2012), bituminous mixes (Skaf et al., 2017), fertilizer (Yi et al., 2012) and soil improvement (Poh et al., 2006). Several studies have also evaluated the feasibility of steel slags for CO2 mineralization (Pan et al., 2017; Yu and Wang, 2011) and water pollution control (Drizo et al., 2006). In the US, about 60.3% of the total steel slag production is directly used as road base, while the remainder is used for asphaltic concrete (10.9%), fill (10.8%) and cement clinker production (5.0%) (Ilyushechkin et al., 2012). In China, the utilization ratio of steel slags is less than 30%, found in cement production, chemical admixture for concrete, brick and block manufacturing (NDRC, 2014; Yi et al., 2012).
Due to the high demand for cement and concrete production worldwide, the cement and concrete industries have an increasing interest in finding alternative materials to replace the use of natural resources. Thus, extensive studies have been carried out to explore the possibility of utilizing steel slags as cement and concrete materials. Alternatively, they are involved in cement clinker production, which in turn reduces CO2 emissions and the total cost of the materials used (Reddy et al., 2006). This paper provides a critical review of the valorization of steel slags in cement, concrete and clinker production. The challenges and opportunities of using BOF, EAF and LF slags as supplementary cementitious materials and/or aggregates in cement and concrete are illustrated. The use of steel slags for cement clinker production is also discussed.
Section snippets
Generation processes
In China, BOF slag accounts for about 70% of the annual steel slag production (Cheng and Yang, 2010). In the BOF process (Fig. 1), minor steel scrap and a large amount of molten iron from ironmaking as well as fluxes (lime/dolomite) are added into the furnace, and a 99% pure oxygen flow is applied at supersonic speed through a lance to initiate intense oxidation reactions at a temperature of 1600–1650 °C. Once the desired chemical composition is achieved, the oxygen supply is stopped and the
Generation processes
EAF slag is the steel-making slag generated from the EAF. It is reported that the EAF process is dominating the steel industry of the US with a 55% share of the total steel output in 2006. An EAF is different from a BOF, for example, in the way of energy supply where the former uses high-power electric arcs instead of gaseous fuels (as shown in Fig. 9). Also, steel scrap has become the major feed material in the EAF process together with limited iron scrap, pig iron and direct reduced iron
Generation processes
After primary steelmaking, the refining operations of both carbon and stainless steel can be performed in an LF (Fig. 9), producing the LF slag. The LF process is based on the principles of deoxidation and alloying, temperature and composition homogenization, desulfurization, steel cleanliness improvement, inclusion flotation and the shape control of sulfide and oxide (Pretorius, 2015; Yang et al., 2007). Due to the uses of fluxes (e.g., calcium aluminate or CaF2) in the LF process, the
Environmental benefits from steel slag valorization
Improper disposal of steel slags can have a deleterious impact on surface- and ground-water through the release of trace elements and hyperalkaline drainage (Piatak et al., 2015). This may greatly threaten the safety of humans and the environment, especially stainless steel slag which contains different heavy metals (Pellegrino and Gaddo, 2009; Xiang et al., 2016; Zhang and Xin, 2011). Salman et al. (2014b, 2015) studied the heavy metals and metalloids leaching from alkali-activated and
Conclusions
The valorization of BOF, EAF and LF slags is an important strategy on industrial waste management toward a circular economy. One of the valorization pathways with great potential is for cement and concrete production. BOF slag is more alkaline and reactive than EAF and LF slags, which could be used as supplementary cementitious materials at a substitution ratio of 10–20 wt.% with satisfactory performance. The rock-like appearance of BOF slag also allows for its use as aggregates in concrete.
Acknowledgments
The research funding from Hunan Provincial Science and Technology Department (Hunan Province Key Research Project, 2017WK2090) and the National Natural Science Foundation of China (NSFC International (Regional) Cooperation and Exchange Program, 51750110506) are gratefully acknowledged.
References (114)
- et al.
Concretes made of EAF slag and AOD slag aggregates from stainless steel process: mechanical properties and durability
Constr. Build. Mater.
(2015) - et al.
Mineralogical composition of EAF slag and stabilised AOD slag aggregates and dimensional stability of slag aggregate concretes
Constr. Build. Mater.
(2016) - et al.
Physico-chemical characteristics of blended cement pastes containing electric arc furnace slag with and without silica fume
HBRC J.
(2015) - et al.
Durability studies on steelmaking slag concretes
Mater. Des.
(2014) - et al.
Effects of thin-film accelerated carbonation on steel slag leaching
J. Hazard. Mater.
(2015) - et al.
Characterization and activation of basic oxygen furnace slag
Cem. Concr. Compos.
(2012) - et al.
Properties of hydraulic paste of basic oxygen furnace slag
Cem. Concr. Compos.
(2014) - et al.
The recycling effect of BOF slag in the Portland cement properties
Resour. Conserv. Recycl.
(2017) - et al.
Engineering properties and performance of asphalt mixtures incorporating steel slag
Constr. Build. Mater.
(2016) - et al.
Hydration properties of ladle furnace slag powder rapidly cooled by air
Constr. Build. Mater.
(2016)
Study on the treatment of BOF slag to replace fine aggregate in concrete
Constr. Build. Mater.
Phosphorus removal by electric arc furnace steel slag and serpentinite
Water Res.
Use of steelworks slag in Europe
Waste Manage.
Hydration heat evolution and kinetics of blended cement containing steel slag at different temperatures
Thermochim. Acta
Hydration characteristics of Portland cement – electric arc furnace slag blends
HBRC J.
On the use of blast furnace slag and steel slag in the preparation of green artificial reef concrete
Constr. Build. Mater.
Ladle metallurgy stainless steel slag as a raw material in ordinary Portland cement production: a possibility for industrial symbiosis
J. Clean. Prod.
Valorisation of electric arc furnace steel slag as raw material for low energy belite cements
J. Hazard. Mater.
Synthesis, characterization and properties of calcium ferroaluminate belite cements produced with electric arc furnace steel slag as raw material
Cem. Concr. Compos.
Improving the mechanical properties of rapid air cooled ladle furnace slag powder by gypsum
Constr. Build. Mater.
Effect of mechanical activation on the hydraulic properties of stainless steel slags
Cem. Concr. Res.
Structural characteristics and hydration kinetics of modified steel slag
Cem. Concr. Res.
Building green supply chains in eco-industrial parks towards a green economy: barriers and strategies
J. Environ. Manage.
Cementitious property modification of basic oxygen furnace steel slag
Constr. Build. Mater.
Effects of temperature and carbonation curing on the mechanical properties of steel slag-cement binding materials
Constr. Build. Mater.
Durability of concrete made with EAF slag as aggregate
Cem. Concr. Compos.
Comparison of properties of steel slag and crushed limestone aggregate concretes
Constr. Build. Mater.
The effect of chemical composition on the leaching behaviour of electric arc furnace (EAF) carbon steel slag during a standard leaching test
J. Environ. Chem. Eng.
Producing Portland cement from iron and steel slags and limestone
Cem. Concr. Res.
Cementitious and pozzolanic behavior of electric arc furnace steel slags
Cem. Concr. Res.
Durability studies on eco-friendly concrete mixes incorporating steel slag as coarse aggregates
J. Clean. Prod.
Integrated and innovative steel slag utilization for iron reclamation, green material production and CO2, fixation via accelerated carbonation
J. Clean. Prod.
ITZ properties of concrete with carbonated steel slag aggregate in salty freeze-thaw environment
Constr. Build. Mater.
Autogenous and engineered healing mechanisms of carbonated steel slag aggregate in concrete
Constr. Build. Mater.
Utilization of carbonated and granulated steel slag aggregate in concrete
Constr. Build. Mater.
Experimental evaluation of high performance base course and road base asphalt concrete with electric arc furnace steel slags
J. Hazard. Mater.
Recycling of waste aggregate in cement bound mixtures for road pavement bases and sub-bases
Constr. Build. Mater.
Properties of concretes with black/oxidizing electric arc furnace slag aggregate
Cem. Concr. Compos.
Mechanical and durability characteristics of concrete containing EAF slag as aggregate
Cem. Concr. Compos.
Characteristics and environmental aspects of slag: a review
Appl. Geochem.
The use of steel slag aggregate to enhance the mechanical properties of recycled aggregate concrete and retain the environment
Constr. Build. Mater.
Utilization of basic oxygen furnace (BOF) slag in the production of a hydraulic cement binder
Int. J. Miner. Process.
Performance of steel slag and steel sludge in concrete
Constr. Build. Mater.
Effect of accelerated carbonation on AOD stainless steel slag for its valorisation as a CO2-sequestering construction material
Chem. Eng. J.
Effect of curing temperatures on the alkali activation of crystalline continuous casting stainless steel slag
Constr. Build. Mater.
Effect of accelerated carbonation on AOD stainless steel slag for its valorisation as a CO2-sequestering construction material
Chem. Eng. J.
Cementitious binders from activated stainless steel refining slag and the effect of alkali solutions
J. Hazard. Mater.
The performance of steel-making slag concretes in the hardened state
Mater. Des.
The use of steelmaking slags and fly ash in structural mortars
Constr. Build. Mater.
Innovative usages of stainless steel slags in developing self-compacting concrete
Constr. Build. Mater.
Cited by (494)
Sustainable development and performance assessment of concrete incorporating biofuel waste
2024, Case Studies in Construction MaterialsEffect of calcined clays from Victoria, Australia as cement substitution in ternary blended cement systems
2024, Case Studies in Construction MaterialsMechanical properties and microstructure of coal cinder-based ultra-fine tailings cemented tailings body
2024, Case Studies in Construction MaterialsThe property, structure, and phase evolution of a binary cementitious material derived from sintering flue gas desulphurization ash and steel slag
2024, Journal of Building EngineeringEffect of environment conditions on volume deformation of blended cement mortars containing blast furnace slag and steel slag powder
2024, Journal of Building Engineering