Phase dissolution and improving properties of completely decomposed granite through alkali fusion method

Dassekpo, J.-B.M. and Miao, L. and Bai, J. and Gong, Q. and Shao, N.N. and Dong, Z. and Xing, F. and Ye, J. (2022) Phase dissolution and improving properties of completely decomposed granite through alkali fusion method. Cement and Concrete Composites, 127. ISSN 0958-9465

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Abstract

Low-reactive completely decomposed granite (CDG) was successfully synthesized by thermal activation with the addition of NaOH at low alkali/CDG mass ratio of 0.1/1. During alkali fusion, the degree of amorphicity of CDG rich in kaolinite (Al2Si2O5(OH)4) increased and a significant reduction of the peak intensities occurring between 20 and 45 (o2 theta) was observed. Reactivity analysis indicated that, initial CDG requires high molar NaOH to provide a proper dissolution, whereas fused CDG exhibits high reactivity (29Si = 555.57 ppm; 27Al = 223.73 ppm) at low NaOH concentration. Moreover, results from the setting time, varied between 15 and 45 min, indicating that alkali fusion is very effective for improving the dissolution of the fused CDG under Na2SiO3 solution. However, the setting time decreases as the reaction degree accelerates. FTIR analysis of the fused CDG presented lower wavenumber band of around 975 cm−1, confirming a decline of crystalline phases. In addition, SEM-EDS characterization and alkalinity analysis showed a compactness of the structure due to the liberation of enough sodium aluminosilicate gel. Finally, results from the mechanical test (4.75–39.55 MPa) and water solubility inferred that, by enhancing the reactivity of CDG by alkali fusion and by addition of up to 15% GGBS, CDG can be optimally recycled as an alternative source material to produce geopolymers.

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, 127, 2022 DOI: 10.1016/j.cemconcomp.2022.104407
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/2500
Subjects:
ID Code:
164872
Deposited By:
Deposited On:
20 Jan 2022 17:00
Refereed?:
Yes
Published?:
Published
Last Modified:
04 May 2022 02:39