Analysing and Manipulating the Nanostructure of Geopolymers

Abstract

Abstract. Geopolymer concretes are currently being commercialised in Australia and elsewhere around the world, with a view towards enhancing the sustainability of the world's construction industry. The fundamental geopolymer binder is an aluminosilicate gel which displays key structural features on every length scale from Ångstroms up to centimetres, meaning that multiscale analysis is key to the development of a detailed understanding of geopolymer formation and performance. Here, we present results from investigations of geopolymer nanostructure, focusing on the use of infrared spectroscopy as an analytical tool. The effects of different combinations of precursors in geopolymer formation provides critical information, in particular with regard to the rate of reaction and its impact on the final distribution of elements and structures within the geopolymer binder. Formulations are designed so that the same composition is obtained by the use of precursors which release their constituent elements at very different rates under alkaline attack during geopolymerisation, and this provides essential information regarding the role of different elements in forming strong and durable geopolymer structures. Seeding the geopolymer mixture with very low doses of oxide nanoparticles presents several unexpected effects, both in terms of reaction kinetics and also in altering the nature of the zeolitic crystallites formed within the predominantly X-ray amorphous geopolymer binder.

Effects of Portland cement on activation mechanism of class F fly ash geopolymer cured under ambient conditions

“…The shift of the main peak towards higher wavenumbers observed between 24 h and 7 days is attributed to the formation of the gel network. The peak is shifted towards higher wavenumbers for sample with a higher initial availability of monomeric silica which can promote the structure formation [43]. Nevertheless, after longer curing periods (28 days) the position of the main peak becomes stable, regardless of the used activator.…”