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

D’Elia, Angela; Pinto, Daniela; Eramo, Giacomo; Laviano, Rocco; Palomo, Angel; Fernández-Jiménez, Ana

doi:10.3390/app10072203

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

by

Angela D’Elia

¹,

Daniela Pinto

^1,*

,

Giacomo Eramo

¹

,

Rocco Laviano

¹

,

Angel Palomo

² and

Ana Fernández-Jiménez

^2,*

¹

Dipartimento di Scienze della Terra e Geoambientali, Università degli Studi di Bari Aldo Moro, 70121 Bari, Italy

²

Instituto Eduardo Torroja (CSIC), 28033 Madrid, Spain

^*

Authors to whom correspondence should be addressed.

Appl. Sci. 2020, 10(7), 2203; https://doi.org/10.3390/app10072203

Submission received: 25 February 2020 / Revised: 13 March 2020 / Accepted: 16 March 2020 / Published: 25 March 2020

(This article belongs to the Special Issue Low Binder Concrete and Mortars)

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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.

Keywords: carbonate-high illite clay; alkali activation; NaOH; activator concentration

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D’Elia, A.; Pinto, D.; Eramo, G.; Laviano, R.; Palomo, A.; Fernández-Jiménez, A. Effect of Alkali Concentration on the Activation of Carbonate-High Illite Clay. Appl. Sci. 2020, 10, 2203. https://doi.org/10.3390/app10072203

AMA Style

D’Elia A, Pinto D, Eramo G, Laviano R, Palomo A, Fernández-Jiménez A. Effect of Alkali Concentration on the Activation of Carbonate-High Illite Clay. Applied Sciences. 2020; 10(7):2203. https://doi.org/10.3390/app10072203

Chicago/Turabian Style

D’Elia, Angela, Daniela Pinto, Giacomo Eramo, Rocco Laviano, Angel Palomo, and Ana Fernández-Jiménez. 2020. "Effect of Alkali Concentration on the Activation of Carbonate-High Illite Clay" Applied Sciences 10, no. 7: 2203. https://doi.org/10.3390/app10072203

APA Style

D’Elia, A., Pinto, D., Eramo, G., Laviano, R., Palomo, A., & Fernández-Jiménez, A. (2020). Effect of Alkali Concentration on the Activation of Carbonate-High Illite Clay. Applied Sciences, 10(7), 2203. https://doi.org/10.3390/app10072203

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

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

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