Basic oxygen furnace (BOF) slag cementitious binder activated by Na4EDTA

Zhihan Jiang; Xuan Ling; Quan Liu; Helong Song; Katrin Schollbach; H.J.H. (Jos) Brouwers

doi:10.1016/j.cemconres.2025.107983

Basic oxygen furnace (BOF) slag cementitious binder activated by Na4EDTA

Zhihan Jiang, Xuan Ling (Corresponding author), Quan Liu, Helong Song, Katrin Schollbach, H.J.H. (Jos) Brouwers

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Abstract

Basic oxygen furnace (BOF) slag contains two potentially hydraulically reactive phases, belite (C2S) and brownmillerite (C2(A,F)), yet exhibits low reactivity. This study proposes ethylenediaminetetraacetic acid tetrasodium salt (Na4EDTA) as a hydration activator and investigates its effects on BOF slag phase evolution, early hydration kinetics, microstructural development, mechanical properties, and leaching behaviors. The EDTA4− chelation mechanism in the BOF slag system is also discussed. Results show that Na4EDTA significantly enhances BOF slag hydration, producing a stand-alone binder with high compressive strength (38.8 MPa at 28 d, v.s. 8.6 MPa of the reference) and reduced porosity. At 4.8 wt% Na4EDTA, brownmillerite reacts almost completely within one day. Belite hydration is also enhanced, particularly at early ages. The main hydration products are hydrogarnet and C-S-H gel. EDTA itself is likely partially incorporated into the layered double hydroxides (LDHs) structure of hydrotalcite. Heavy metal leaching is below the Dutch legal limits.

Original language	English
Article number	107983
Number of pages	18
Journal	Cement and Concrete Research
Volume	198
DOIs	https://doi.org/10.1016/j.cemconres.2025.107983
Publication status	Published - Dec 2025

Funding

This work was supported by the China Scholarship Council (fund No. 202006950032 ). We express our sincere gratitude to Anneke Delsing for the help in the ICP-AES analysis. We would also like to thank Tata Steel (The Netherlands) for offering the raw BOF slag.

Keywords

BOF slag binder
Chelation-promoted hydration
Leaching
Mineral phase evolution
Tetrasodium EDTA (Na EDTA)

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title = "Basic oxygen furnace (BOF) slag cementitious binder activated by Na4EDTA",

abstract = "Basic oxygen furnace (BOF) slag contains two potentially hydraulically reactive phases, belite (C2S) and brownmillerite (C2(A,F)), yet exhibits low reactivity. This study proposes ethylenediaminetetraacetic acid tetrasodium salt (Na4EDTA) as a hydration activator and investigates its effects on BOF slag phase evolution, early hydration kinetics, microstructural development, mechanical properties, and leaching behaviors. The EDTA4− chelation mechanism in the BOF slag system is also discussed. Results show that Na4EDTA significantly enhances BOF slag hydration, producing a stand-alone binder with high compressive strength (38.8 MPa at 28 d, v.s. 8.6 MPa of the reference) and reduced porosity. At 4.8 wt\% Na4EDTA, brownmillerite reacts almost completely within one day. Belite hydration is also enhanced, particularly at early ages. The main hydration products are hydrogarnet and C-S-H gel. EDTA itself is likely partially incorporated into the layered double hydroxides (LDHs) structure of hydrotalcite. Heavy metal leaching is below the Dutch legal limits.",

keywords = "BOF slag binder, Chelation-promoted hydration, Leaching, Mineral phase evolution, Tetrasodium EDTA (Na EDTA)",

author = "Zhihan Jiang and Xuan Ling and Quan Liu and Helong Song and Katrin Schollbach and Brouwers, \{H.J.H. (Jos)\}",

year = "2025",

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doi = "10.1016/j.cemconres.2025.107983",

language = "English",

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T1 - Basic oxygen furnace (BOF) slag cementitious binder activated by Na4EDTA

AU - Jiang, Zhihan

AU - Ling, Xuan

AU - Liu, Quan

AU - Song, Helong

AU - Schollbach, Katrin

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

PY - 2025/12

Y1 - 2025/12

N2 - Basic oxygen furnace (BOF) slag contains two potentially hydraulically reactive phases, belite (C2S) and brownmillerite (C2(A,F)), yet exhibits low reactivity. This study proposes ethylenediaminetetraacetic acid tetrasodium salt (Na4EDTA) as a hydration activator and investigates its effects on BOF slag phase evolution, early hydration kinetics, microstructural development, mechanical properties, and leaching behaviors. The EDTA4− chelation mechanism in the BOF slag system is also discussed. Results show that Na4EDTA significantly enhances BOF slag hydration, producing a stand-alone binder with high compressive strength (38.8 MPa at 28 d, v.s. 8.6 MPa of the reference) and reduced porosity. At 4.8 wt% Na4EDTA, brownmillerite reacts almost completely within one day. Belite hydration is also enhanced, particularly at early ages. The main hydration products are hydrogarnet and C-S-H gel. EDTA itself is likely partially incorporated into the layered double hydroxides (LDHs) structure of hydrotalcite. Heavy metal leaching is below the Dutch legal limits.

AB - Basic oxygen furnace (BOF) slag contains two potentially hydraulically reactive phases, belite (C2S) and brownmillerite (C2(A,F)), yet exhibits low reactivity. This study proposes ethylenediaminetetraacetic acid tetrasodium salt (Na4EDTA) as a hydration activator and investigates its effects on BOF slag phase evolution, early hydration kinetics, microstructural development, mechanical properties, and leaching behaviors. The EDTA4− chelation mechanism in the BOF slag system is also discussed. Results show that Na4EDTA significantly enhances BOF slag hydration, producing a stand-alone binder with high compressive strength (38.8 MPa at 28 d, v.s. 8.6 MPa of the reference) and reduced porosity. At 4.8 wt% Na4EDTA, brownmillerite reacts almost completely within one day. Belite hydration is also enhanced, particularly at early ages. The main hydration products are hydrogarnet and C-S-H gel. EDTA itself is likely partially incorporated into the layered double hydroxides (LDHs) structure of hydrotalcite. Heavy metal leaching is below the Dutch legal limits.

KW - BOF slag binder

KW - Chelation-promoted hydration

KW - Leaching

KW - Mineral phase evolution

KW - Tetrasodium EDTA (Na EDTA)

UR - https://www.scopus.com/pages/publications/105010191349

U2 - 10.1016/j.cemconres.2025.107983

DO - 10.1016/j.cemconres.2025.107983

M3 - Article

SN - 0008-8846

VL - 198

JO - Cement and Concrete Research

JF - Cement and Concrete Research

M1 - 107983

ER -

Basic oxygen furnace (BOF) slag cementitious binder activated by Na4EDTA

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