Longitudinal single-sided NMR study: Silica-to-alumina ratio changes the reaction mechanism of geopolymer. (October 2022)

• Record Type: Journal Article
• Authors: Li, Jing; Mailhiot, Sarah; Kantola, Anu M.; Niu, He; Sreenivasan, Harisankar; Telkki, Ville-Veikko; Kinnunen, Paivo
• Is Part Of: Cement and concrete research. Volume 160(2022)
• Publication Date: 2022-10
• Subjects: Metakaolin-based geopolymers -- Single-sided NMR -- Geopolymerization -- Silica-to-alumina ratio -- 1H relaxation NMR; Cement -- Periodicals; Cement -- Research -- Periodicals; Concrete -- Periodicals; Concrete -- Research -- Periodicals; Ciment -- Périodiques; Béton -- Périodiques; Cement; Concrete; Periodicals; 620.135
• DOI: 10.1016/j.cemconres.2022.106921
• Languages: English
• ISSNs: 0008-8846

Abstract

Abstract: Characterizing and understanding the mechanisms underlying geopolymerization are critical in achieving the use of sustainable construction material, geopolymer, for widespread commercial production. Non-destructive 1 H NMR relaxometry can provide novel information about geopolymerization as it allows simultaneous detection of where the water goes and how the pore structure changes. Coupled with the development of single-sided NMR devices, NMR measurements are not limited by the specimen size and are therefore able to observe in-situ conditions of geopolymer synthesis. Here, the curing process of metakaolin-based geopolymers was monitored by 1 H relaxometry on a single-sided NMR device. The silica-to-alumina ratio ( Si / Al ) was found to affect reaction stages of the geopolymerization. After the dissolution of aluminosilicate precursor, the low Si / Al of 1 was found to generate three gelation/polymerization stages as well as a water-binding stage, and two gel phases appeared. When Si / Al varied in 1.5–2.5, two gelation/polymerization stages and only one gel phase was observed.