Fang, G;
Zhang, M;
(2020)
The evolution of interfacial transition zone in alkali-activated fly ash-slag concrete.
Cement and Concrete Research
, 129
, Article 105963. 10.1016/j.cemconres.2019.105963.
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Abstract
This paper investigates the mechanisms of microstructure evolution of interfacial transition zone (ITZ) in alkali-activated fly ash-slag (AAFS) concrete using scanning electron microscope. Results indicate that the formation of original ITZ depends on the so-called “wall effect”, leading to a deficit of large grains and a higher effective alkaline activator/precursor ratio compared to paste matrix. The alkaline reaction process is correspondingly accelerated, which promotes the formation of low Ca C-(N)-A-S-H gels and reduces the porosity in the ITZ. Afterwards, the high Ca C-(N)-A-S-H gels are generated due to the release of more Ca from slag, resulting in the continuous refinement of pores. The C-(N)-A-S-H gels with rich Si and Al are then produced at 7 d, attributing to the species diffusion from paste matrix to ITZ. Consequently, a compact and dense microstructure is formed in the ITZ at 28 d, which would be beneficial to the long-term performance of concrete.
| Type: | Article |
|---|---|
| Title: | The evolution of interfacial transition zone in alkali-activated fly ash-slag concrete |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1016/j.cemconres.2019.105963 |
| Publisher version: | https://doi.org/10.1016/j.cemconres.2019.105963 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Alkali-activated materials (D), Microstructure (B), Pore size distribution (B), Backscattered electron imaging (B), X-ray mapping (B) |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Civil, Environ and Geomatic Eng UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10089440 |
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