Cold reaction sintering for preparation of ultra-dense geopolymer products. (18th April 2022)

• Record Type: Journal Article
• Authors: Nishikawa, Kosuke; Hashimoto, Shinobu; Imai, Haruo; Rossignol, Sylvie
• Is Part Of: Construction & building materials. Volume 328(2022)
• Publication Date: 2022-04-18
• Subjects: Geopolymer -- Cold reaction sintering -- Warm press -- Geomimetic ceramic -- Ultra-dense polymeric material; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2022.127101
• Languages: English
• ISSNs: 0950-0618

Abstract

Graphical abstract: Highlights: Ultra-dense geopolymer products were fabricated by the cold reaction sintering. The compressive strength of the geopolymer hardened body showed maximum 425 MPa. The relative density of the resultant geopolymer reached to maximum 98% The key point was to use the hydrate as a raw material instead of aqueous solution. Abstract: Geopolymers are attractive materials that contribute to carbon neutrality because they can significantly reduce CO2 emissions compared to traditional Portland-based cement manufacturing. Geopolymers generally take several days to weeks to cure and have low mechanical properties. This paper proposes a new hardening method using a warm press, called "cold reaction sintering", in order to obtain a hardened body with high strength in a shorter time than conventional geopolymers. In general, to harden geopolymers use an alkaline solution such as NaOH. In this study, sodium metasilicate hydrate (Na2 SiO3 ·nH2 O) was used instead of the alkaline solution. As a result of examining the composition, temperature and holding time, the maximum compressive strength value of 425 MPa was obtained when hardened at uniaxial pressure 100 MPa, 130° C for only 10 min with fly ash: Na2 SiO3 : Na2 SiO3 ·9H2 O (68: 16: 16 wt%, respectively). In addition, dimensional change measurements during hardening, FTIR and NMR analysis were preformed to investigate and discuss the mechanism of geopolymer hardening.