Structural alterations in alkali-sulfate-activated slag cement pastes induced by natural and accelerated carbonation

Zengliang Yue; Yuvaraj Dhandapani; Susan A. Bernal

doi:10.1016/j.cemconres.2024.107713

Structural alterations in alkali-sulfate-activated slag cement pastes induced by natural and accelerated carbonation

Zengliang Yue, Yuvaraj Dhandapani, Susan A. Bernal

University of Leeds

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

4 Citations (SciVal)

Abstract

The impact of carbonation, induced at different CO₂ concentrations (0.04 or 1 %), in the phase assemblages and compressive strength of Na₂SO₄-activated slag materials was determined. Carbonation led to Ca-bearing phases' decalcification (mainly C-(A)-S-H type gel and ettringite) forming different CaCO₃ polymorphs, independent of the slag composition or carbonation conditions adopted. In specimens exposed to 0.04 % CO₂, a negligible carbonation front was observed, along with a continued phase assemblage evolution and compressive strength gain after 500 days of exposure. Conversely, exposure to 1 % CO₂ led to complete carbonation after 28 days, and a significant compressive strength reduction. Accelerated carbonation does not lead to the development of comparable microstructures to those observed in naturally carbonated pastes. The accelerated carbonation rates were ~ 33 times higher than those determined under natural carbonation exposure. Therefore, accelerated tests are considered unsuitable for predicting the long-term carbonation performance of Na₂SO₄-activated slag cements.

Original language	English
Article number	107713
Journal	Cement and Concrete Research
Volume	187
Early online date	4 Nov 2024
DOIs	https://doi.org/10.1016/j.cemconres.2024.107713
Publication status	Published - 1 Jan 2025

Data Availability Statement

The data associated with this paper are openly available from the University of Leeds Data Repository, at https://doi.org/10.5518/1557.

DOI link with all the data has been included in the revised version of the paper

Funding

This research was sponsored by the Engineering and Physics Science Research Council (EPSRC) via an early career fellowship EP/R001642/1. Z. Yue is grateful to the University of Leeds for his PhD studentship. The SEM analysis was conducted at the UKCRIC National Centre for Infrastructure Materials at the University of Leeds grant EP/P017169/1. Stuart King and Duncan Hedges are greatly acknowledged for training in SEM sample preparation. The discussions about this study with Dr. Sam Adu-Amankwah (University of Aston) are highly acknowledged.

Keywords

Alkali-activated slag cements
Carbonation
Characterization
Durability
Granulated blast furnace slag

ASJC Scopus subject areas

Building and Construction
General Materials Science

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10.1016/j.cemconres.2024.107713Licence: CC BY

Cite this

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title = "Structural alterations in alkali-sulfate-activated slag cement pastes induced by natural and accelerated carbonation",

abstract = "The impact of carbonation, induced at different CO2 concentrations (0.04 or 1 %), in the phase assemblages and compressive strength of Na2SO4-activated slag materials was determined. Carbonation led to Ca-bearing phases' decalcification (mainly C-(A)-S-H type gel and ettringite) forming different CaCO3 polymorphs, independent of the slag composition or carbonation conditions adopted. In specimens exposed to 0.04 % CO2, a negligible carbonation front was observed, along with a continued phase assemblage evolution and compressive strength gain after 500 days of exposure. Conversely, exposure to 1 % CO2 led to complete carbonation after 28 days, and a significant compressive strength reduction. Accelerated carbonation does not lead to the development of comparable microstructures to those observed in naturally carbonated pastes. The accelerated carbonation rates were ~ 33 times higher than those determined under natural carbonation exposure. Therefore, accelerated tests are considered unsuitable for predicting the long-term carbonation performance of Na2SO4-activated slag cements.",

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N2 - The impact of carbonation, induced at different CO2 concentrations (0.04 or 1 %), in the phase assemblages and compressive strength of Na2SO4-activated slag materials was determined. Carbonation led to Ca-bearing phases' decalcification (mainly C-(A)-S-H type gel and ettringite) forming different CaCO3 polymorphs, independent of the slag composition or carbonation conditions adopted. In specimens exposed to 0.04 % CO2, a negligible carbonation front was observed, along with a continued phase assemblage evolution and compressive strength gain after 500 days of exposure. Conversely, exposure to 1 % CO2 led to complete carbonation after 28 days, and a significant compressive strength reduction. Accelerated carbonation does not lead to the development of comparable microstructures to those observed in naturally carbonated pastes. The accelerated carbonation rates were ~ 33 times higher than those determined under natural carbonation exposure. Therefore, accelerated tests are considered unsuitable for predicting the long-term carbonation performance of Na2SO4-activated slag cements.

AB - The impact of carbonation, induced at different CO2 concentrations (0.04 or 1 %), in the phase assemblages and compressive strength of Na2SO4-activated slag materials was determined. Carbonation led to Ca-bearing phases' decalcification (mainly C-(A)-S-H type gel and ettringite) forming different CaCO3 polymorphs, independent of the slag composition or carbonation conditions adopted. In specimens exposed to 0.04 % CO2, a negligible carbonation front was observed, along with a continued phase assemblage evolution and compressive strength gain after 500 days of exposure. Conversely, exposure to 1 % CO2 led to complete carbonation after 28 days, and a significant compressive strength reduction. Accelerated carbonation does not lead to the development of comparable microstructures to those observed in naturally carbonated pastes. The accelerated carbonation rates were ~ 33 times higher than those determined under natural carbonation exposure. Therefore, accelerated tests are considered unsuitable for predicting the long-term carbonation performance of Na2SO4-activated slag cements.

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Structural alterations in alkali-sulfate-activated slag cement pastes induced by natural and accelerated carbonation

Abstract

Data Availability Statement

Funding

Keywords

ASJC Scopus subject areas

Access to Document

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