Evolution of ITZ and its effect on the carbonation depth of concrete under supercritical CO2 condition

Bao, H. and Xu, G. and Yu, M. and Wang, Q. and Li, R. and Saafi, M. and Ye, J. (2022) Evolution of ITZ and its effect on the carbonation depth of concrete under supercritical CO2 condition. Cement and Concrete Composites, 126. ISSN 0958-9465

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Abstract

In this paper, supercritical carbonation tests of concrete specimens with different water-to-cement ratios are carried out. In the test, the thickness of interfacial transition zone (ITZ) of the concrete is determined by the distribution of Ca/Si ratio across the interface between the coarse aggregate and cement paste. The microhardness distribution, microstructure and porosity of the ITZ before and after supercritical carbonation are analyzed. A geometrical and physical model considering the distribution of porosity, coarse aggregates, ITZ, and the supercritical carbonation of concrete is proposed, by which cracks, pores, calcium carbonates, and C-S-H gel at the interface of coarse aggregates and cement paste can be studied. The overall microstructures are relatively compacted after supercritical carbonation. The thickness of ITZ of concrete is reduced from 47-79 μm to 35–51 μm after supercritical carbonation. The average value and variance of carbonation depth of concrete increase with the increase of the thickness and porosity of ITZ. Comparing the carbonation results of concrete with different thicknesses and porosity of ITZ, it appears that porosity of ITZ has greater impact on the carbonation depth of concrete.

Item Type:
Journal Article
Journal or Publication Title:
Cement and Concrete Composites
Additional Information:
This is the author’s version of a work that was accepted for publication in Cement and Concrete Composites. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Cement and Concrete Composites, 126, 2022 DOI: 10.1016/j.cemconcomp.2021.104336
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/2500
Subjects:
ID Code:
163790
Deposited By:
Deposited On:
05 Jan 2022 17:20
Refereed?:
Yes
Published?:
Published
Last Modified:
22 Nov 2022 10:57