The Influence of Rice Husk Ash Addition on the Properties of Metakaolin-Based Geopolymers
Paulo H. R. Borges1, *, Vitor A. Nunes1, Tulio H. Panzera2, Giorgio Schileo3, Antonio Feteira3
Identifiers and Pagination:Year: 2016
Issue: Suppl 3: M4
First Page: 406
Last Page: 417
Publisher Id: TOBCTJ-10-406
Article History:Received Date: 22/4/2015
Revision Received Date: 20/5/2015
Acceptance Date: 5/11/2015
Electronic publication date: 28/06/2016
Collection year: 2016
open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution-Non-Commercial 4.0 International Public License (CC BY-NC 4.0) (https://creativecommons.org/licenses/by-nc/4.0/legalcode), which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.
This paper investigates the replacement of metakaolin (MK) with rice husk ash (RHA) in the production of alkali-activated binders or geopolymers. The influence of the RHA addition on compressive and flexural strength, as well as water absorption and apparent porosity were determined, in terms of the percentage of RHA in the mixture and molar ratios of the mixes. Fourier Transform Infrared (FTIR) spectroscopy and Energy Dispersive spectroscopy (EDS) were carried out to assess the changes in the microstructure of the geopolymer matrices with the RHA addition. Results have shown that RHA may be a supplementary precursor for geopolymers. The composition of the geopolymer matrices containing 0-40% RHA is very similar, which indicates that the additional Si provided by RHA is not incorporated to the geopolymer matrix. In addition, geopolymers with RHA content higher than 40% present a plastic behavior, characterized by extremely low strength and high deformation, which can be attributed to the formation of silica gel in formulations containing variable Si/Al ratio.