title: Cementitious binders from activated stainless steel refining slag and the effect of alkali solutions.
abstract: With an aim of producing high value cementitious binder, stainless steel refining slag containing a high amount of CaO in γ-dicalcium silicate form was activated with NaOH and Na-silicate as well as KOH and K-silicate solutions, followed by steam curing at 80 °C. Higher levels of alkali-silicate in the activating solution resulted in higher cumulative heat suggesting accelerated reaction kinetics. With respect to compressive strength, higher levels of alkali silicate resulted in higher strength and the mortars with Na activator were found to have higher early strength than the ones with K activator. The long term strength was found to be similar, regardless of the alkali metal. Thermogravimetric, QXRD and FTIR analyses showed an increase in the amount of reaction products (C-S-H type) over time, further confirming the reactivity of the crystalline slag. Batch leaching results showed lower leaching of heavy metals and metalloids with K activator compared to the Na activator. These results demonstrate that the alkali type and the ratio of hydroxide to silicates have a significant impact on the hydration and mechanical strength development of the stainless steel slag. The above findings can aid in the recycling and valorization of these type of slags which otherwise end up landfilled.
authors.affiliation: KU Leuven, Department of Civil Engineering, Kasteelpark Arenberg 40, 3001 Leuven, Belgium.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Salman
authors.affiliation: KU Leuven, Department of Civil Engineering, Kasteelpark Arenberg 40, 3001 Leuven, Belgium.
authors.forename: Özlem
authors.initials: Ö
authors.lastname: Cizer
authors.affiliation: KU Leuven, High Temperature Processes and Industrial Ecology, Department of Materials Engineering, KU Leuven, Kasteelpark Arenberg 44, 3001 Leuven, Belgium. Electronic address: Yiannis.Pontikes@mtm.kuleuven.be.
authors.forename: Yiannis
authors.initials: Y
authors.lastname: Pontikes
authors.affiliation: KU Leuven, Department of Earth and Environmental Sciences, Celestijnenlaan 200E, 3001 Leuven, Belgium.
authors.forename: Ruben
authors.initials: R
authors.lastname: Snellings
authors.affiliation: KU Leuven, Department of Civil Engineering, Kasteelpark Arenberg 40, 3001 Leuven, Belgium.
authors.forename: Lucie
authors.initials: L
authors.lastname: Vandewalle
authors.affiliation: KU Leuven, High Temperature Processes and Industrial Ecology, Department of Materials Engineering, KU Leuven, Kasteelpark Arenberg 44, 3001 Leuven, Belgium.
authors.forename: Bart
authors.initials: B
authors.lastname: Blanpain
authors.affiliation: KU Leuven, Department of Civil Engineering, Kasteelpark Arenberg 40, 3001 Leuven, Belgium.
authors.forename: Koen
authors.initials: K
authors.lastname: Van Balen
mesh_terms: D019245:Compressive Strength; D003252:Construction Materials; D006358:Hot Temperature; D006878:Hydroxides / Q000737:chemistry*; D017680:Potassium Compounds / Q000737:chemistry*; D059027:Recycling; D017640:Silicates / Q000737:chemistry*; D012972:Sodium Hydroxide / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013193:Stainless Steel / Q000737:chemistry*; D013818:Thermogravimetry
chemical_list: D006878:Hydroxides; D017680:Potassium Compounds; D017640:Silicates; D013193:Stainless Steel; D012972:Sodium Hydroxide; C029943:potassium hydroxide
keywords: Alkali activated cement; Compressive strength; Leaching; Phase analysis; Stainless steel slag; Thermal analysis