Effect of phase composition on the reactivity of DRI-EAF slags as SCM

Morteza Tayebi; Katrin Schollbach; Jonathan C.O. Zepper; Stefan Melzer; H.J.H. (Jos) Brouwers

doi:10.1016/j.cemconres.2026.108160

Effect of phase composition on the reactivity of DRI-EAF slags as SCM

Morteza Tayebi (Corresponding author)
, Katrin Schollbach
, Jonathan C.O. Zepper
, Stefan Melzer
, H.J.H. (Jos) Brouwers

Research output: Contribution to journal › Article › Academic › peer-review

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Abstract

DRI in EAFs will reduce the availability of blast-furnace slag, necessitating alternative SCMs. Five DRI–EAF slags (four engineered, and one industrial) were investigated, spanning CaO/SiO₂ ≈ 1.3 or 2.0, FeOx ≈25 or 40 wt%, and cooling (air-cooled vs water-granulated). At 25 wt% clinker replacement, hydration and performance were quantified by isothermal and R3 calorimetry, UPV, autogenous shrinkage, XRD/TGA, compressive strength, and leaching. Cooling history, through the control of the amorphous fraction, governed reactivity: water-granulated slags exhibited higher cumulative heat, accelerated set, and superior strength activity indices compared to air-cooled analogues. Basicity and FeOx exerted secondary effects: higher basicity accelerated hydration and reduced autogenous shrinkage, whereas elevated FeOx retarded reaction. All binders formed C–S–H, ettringite, and portlandite; hydrotalcite-like LDHs were detected only for the low-basicity, water-granulated slag. All mortars complied with Dutch leaching limits and met SCM strength benchmarks, evidencing the viability of engineered DRI–EAF slags as low-CO₂ cementitious binders.

Original language	English
Article number	108160
Number of pages	16
Journal	Cement and Concrete Research
Volume	203
Early online date	11 Feb 2026
DOIs	https://doi.org/10.1016/j.cemconres.2026.108160
Publication status	E-pub ahead of print - 11 Feb 2026

Bibliographical note

Publisher Copyright:
© 2026 The Authors

Funding

This research was conducted under project number T23006b within the framework of the Research Program of the Materials Innovation Institute (M2i) (www.m2i.nl), supported by the Dutch government. The authors would like to acknowledge the following sponsors of this research: Tata Steel Netherlands, Heidelberg Materials, Ecocem, and Pelt & Hooykaas.

Keywords

Supplementary cementitious material (SCM)
Electric arc furnace (EAF) slag
Phase assemblage
Reactivity
Sustainable construction materials

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abstract = "DRI in EAFs will reduce the availability of blast-furnace slag, necessitating alternative SCMs. Five DRI–EAF slags (four engineered, and one industrial) were investigated, spanning CaO/SiO₂ ≈ 1.3 or 2.0, FeOx ≈25 or 40 wt\%, and cooling (air-cooled vs water-granulated). At 25 wt\% clinker replacement, hydration and performance were quantified by isothermal and R3 calorimetry, UPV, autogenous shrinkage, XRD/TGA, compressive strength, and leaching. Cooling history, through the control of the amorphous fraction, governed reactivity: water-granulated slags exhibited higher cumulative heat, accelerated set, and superior strength activity indices compared to air-cooled analogues. Basicity and FeOx exerted secondary effects: higher basicity accelerated hydration and reduced autogenous shrinkage, whereas elevated FeOx retarded reaction. All binders formed C–S–H, ettringite, and portlandite; hydrotalcite-like LDHs were detected only for the low-basicity, water-granulated slag. All mortars complied with Dutch leaching limits and met SCM strength benchmarks, evidencing the viability of engineered DRI–EAF slags as low-CO₂ cementitious binders.",

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author = "Morteza Tayebi and Katrin Schollbach and Zepper, \{Jonathan C.O.\} and Stefan Melzer and Brouwers, \{H.J.H. (Jos)\}",

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AU - Tayebi, Morteza

AU - Schollbach, Katrin

AU - Zepper, Jonathan C.O.

AU - Melzer, Stefan

AU - Brouwers, H.J.H. (Jos)

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AB - DRI in EAFs will reduce the availability of blast-furnace slag, necessitating alternative SCMs. Five DRI–EAF slags (four engineered, and one industrial) were investigated, spanning CaO/SiO₂ ≈ 1.3 or 2.0, FeOx ≈25 or 40 wt%, and cooling (air-cooled vs water-granulated). At 25 wt% clinker replacement, hydration and performance were quantified by isothermal and R3 calorimetry, UPV, autogenous shrinkage, XRD/TGA, compressive strength, and leaching. Cooling history, through the control of the amorphous fraction, governed reactivity: water-granulated slags exhibited higher cumulative heat, accelerated set, and superior strength activity indices compared to air-cooled analogues. Basicity and FeOx exerted secondary effects: higher basicity accelerated hydration and reduced autogenous shrinkage, whereas elevated FeOx retarded reaction. All binders formed C–S–H, ettringite, and portlandite; hydrotalcite-like LDHs were detected only for the low-basicity, water-granulated slag. All mortars complied with Dutch leaching limits and met SCM strength benchmarks, evidencing the viability of engineered DRI–EAF slags as low-CO₂ cementitious binders.

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Effect of phase composition on the reactivity of DRI-EAF slags as SCM

Abstract

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Keywords

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