Experimental evaluation of rice husk ash for applications in geopolymer mortars
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Date
2021-02-26
Journal Title
Journal ISSN
Volume Title
Publisher
Keai publishing
Abstract
Rice husks obtained from upland and lowland rice varieties were characterized by the composition and content of ash. Each of the rice husk varieties was fired at temperatures of 600, 800, and 900 °C for a soaking period of 3 h. The resultant rice husk ash was analyzed for oxide composition and crystallinity using X-ray fluorescence and diffraction techniques, respectively. The generated
amorphous ash with the highest silica content, together with metakaolin, aggregate, water, and an alkaline activator was employed to formulate geo-polymer mortar prisms according to the standard EN 196–1. Results showed that the content of ash in the varieties ranged from 18.3% to 28.6% dry basis. Out of this, 89 wt%–96 wt% was silica, with amorphous and crystalline forms
of silica obtained at 600 °C and 900 °C, respectively, regardless of the rice variety. However, at 800 °C, the silica in the generated ash exhibited both amorphous and crystalline forms. The amorphous ash generated at 600 °C was used in the formulation of geopolymer mortars. The compressive and flexural strength of the formulated mortar after 7 days of curing was 1.5 and 1.3 MPa, respectively. These results reveal the firing protocol to form pozzolanic ash, with potential applications
in mortar production.
Description
Keywords
Rice husk ash, Metakaolin, Activator, Geopolymer mortar, Characterization