Review Integrated and innovative steel slag utilization for iron reclamation, green material production and CO 2 fixation via accelerated carbonation Shu-Yuan Pan a , Rahul Adhikari b , Yi-Hung Chen c , Ping Li d , Pen-Chi Chiang a, d, e, * a Graduate Institute of Environmental Engineering, National Taiwan University, Taipei 10673, Taiwan b Indian Institute of Technology, Roorkee, Uttarakhand 247667, India c Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, Taiwan d School of Environment and Energy, South China University of Technology, Guangzhou, Guangdong Province 510006, China e Carbon Cycle Research Center, National Taiwan University, Taipei 10673, Taiwan article info Article history: Received 17 February 2016 Received in revised form 18 July 2016 Accepted 19 July 2016 Available online 20 July 2016 Keywords: Mineralization Cement Aggregate Stabilization Solid waste Valorization abstract Huge amounts of iron and steel slags are generated annually worldwide from integrated manufacturing processes and/or the electric arc furnace. However, conventional uses of untreated iron and steel slags in civil engineering have encountered several technological barriers, such as fatal volume expansion, heavy metal leaching and low cementitious property of slag. In this study, the physico-chemical properties of four different types of slag, blast furnace slag, basic oxygen furnace slag, electric arc furnace slag and ladle refining furnace slag, are illustrated. The challenges and barriers in direct use of steel slags in civil engineering are comprehensively summarized. To overcome the barriers of slag utilization, an acceler- ated carbonation process is proposed and reviewed in terms of theoretical perspectives and practical considerations. Since diluted CO 2 in flue gas can be directly introduced for carbonation, additional environmental and economic benefits such as CO 2 emission reduction are obtained. In addition, the performance of various new carbonated slags or products is systematically reviewed, in terms of changes in the physico-chemical properties of carbonated slag. To facilitate the industrialization of accelerated carbonation, several suggestions are made regarding future research directions. © 2016 Elsevier Ltd. All rights reserved. Contents 1. Introduction ...................................................................................................................... 618 2. Types of iron and steel slags ........................................................................................................ 619 2.1. Blast furnace slag (BFS) ....................................................................................................... 619 2.2. Basic oxygen furnace slag (BOFS) ............................................................................................... 620 2.3. Electric arc furnace slag (EAFS) ................................................................................................ 620 2.4. Ladle furnace slag (LFS) ....................................................................................................... 620 3. Utilization of fresh steel slags in civil engineering ..................................................................................... 621 3.1. Evaluation criteria ........................................................................................................... 621 3.1.1. Workability ......................................................................................................... 621 3.1.2. Mechanical strength .................................................... ............................................. 621 3.1.3. Durability ........................................................................................................... 621 3.2. Direct utilization of fresh steel slags ................................................. .......................................... 621 3.2.1. Coarse aggregates in road, pavement and hydraulic engineering ........................................................... 622 3.2.2. Fine aggregates in concrete ................................................. .......................................... 622 3.2.3. Supplementary cementitious materials in cement ........................................................................ 622 * Corresponding author. 71 Chou-Shan Rd., Taipei City 10673, Taiwan. E-mail address: pcchiang@ntu.edu.tw (P.-C. Chiang). Contents lists available at ScienceDirect Journal of Cleaner Production journal homepage: www.elsevier.com/locate/jclepro http://dx.doi.org/10.1016/j.jclepro.2016.07.112 0959-6526/© 2016 Elsevier Ltd. All rights reserved. Journal of Cleaner Production 137 (2016) 617e631