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Effect of Alkali Concentration on the Activation of Carbonate-High Illite Clay

Authors :
Angela D’Elia
Daniela Pinto
Giacomo Eramo
Rocco Laviano
Angel Palomo
Ana Fernández-Jiménez
Source :
Applied Sciences, Vol 10, Iss 7, p 2203 (2020)
Publication Year :
2020
Publisher :
MDPI AG, 2020.

Abstract

The present study explores the effect of activating solution concentration (4, 6 and 8 M NaOH) on mechanically and thermally pre-treated carbonate-high illite clay (LCR). Pastes were prepared with an alkaline solution/clay (S/B) ratio of 0.55, which were cured at room temperature and relative humidity > 90% in a climatic chamber. At two and 28 days, compressive mechanical strength was determined, and the reaction products were characterised by X-ray Powder Diffraction analysis (XRPD), Fourier-transform infrared spectroscopy (FTIR) and Scanning Electron Microscopy - Energy Dispersive X-ray spectroscopy (SEM/EDX). Results obtained showed that the presence of reactive calcium in the starting clay induces co-precipitation of a mix of gels: An aluminium-enriched C-S-H gel (C-A-S-H) and a N-A-S-H gel, in which sodium is partially replaced by calcium (N,C)-A-S-H. Pastes prepared with higher (6 or 8 M) activator concentrations exhibit a more compact matrix than the ones prepared with 4 M NaOH. The findings show that the use of a 6 M NaOH solution yields a binder with two days compressive strength >20 MPa and 28 days strength of over 30 MPa.

Details

Language :
English
ISSN :
20763417
Volume :
10
Issue :
7
Database :
Directory of Open Access Journals
Journal :
Applied Sciences
Publication Type :
Academic Journal
Accession number :
edsdoj.f98ca7f91f5e42b4823eb222baf04374
Document Type :
article
Full Text :
https://doi.org/10.3390/app10072203