Carbonated steel slag powder in cement: Retardation mechanism and triethanolamine-enhanced hydration strategy

Liu, Peng, Gu, Yahui, Zhong, Jingkui, Kuang, Jiahua, Huang, Xiaojun, Jin, Fei ORCID: https://orcid.org/0000-0003-0899-7063, Zhao, Mingshan and Mo, Liwu 2025. Carbonated steel slag powder in cement: Retardation mechanism and triethanolamine-enhanced hydration strategy. Construction and Building Materials 492 , 142881. 10.1016/j.conbuildmat.2025.142881 Item availability restricted.

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Abstract

The growing demand for low-carbon construction materials has driven interests in utilising carbonated steel slag powder as a supplementary cementitious material (SCM). Accelerated carbonation enhances the reactivity of steel slag and contributes to CO2 sequestration, making it a promising route for sustainable cement production. However, this study reveals that carbonation also alters the steel slags’ physicochemical properties, specifically by lowering basicity and increasing specific surface area SSA, which in turn adversely affects early-age cement hydration. When incorporated into cement, carbonated steel slag powder elevated Ca2 + concentration in the pore solution, suppressing gypsum dissolution and delaying ettringite formation. These effects retard the hydration of aluminate phases and reduce early-age compressive strength of cement pastes. Moreover, in slags with high P2O5 contents, carbonation further inhibits tricalcium silicate (C3S) hydration, preventing Ca(OH)2 formation and exacerbating performance loss. Adding 0.05 wt% triethanolamine (TEA) to the mixing water effectively promotes gypsum dissolution and ettringite formation, enhancing early hydration kinetics and significantly increase the compressive strength of carbonated slag-blended composite cements. This study offers new mechanistic insights into the interaction between carbonated steel slag and cement hydration, and demonstrates a simple, scalable strategy to overcome early-age performance limitations, supporting high-value utilisation of metallurgical wastes in low-carbon cements.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Engineering
Publisher:	Elsevier
ISSN:	0950-0618
Funders:	EPSRC
Date of First Compliant Deposit:	4 August 2025
Date of Acceptance:	24 July 2025
Last Modified:	05 Aug 2025 14:45
URI:	https://orca.cardiff.ac.uk/id/eprint/180217

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