Forming zeolites and calcium silicate hydrates in Fe-rich, slag-based, porous inorganic polymers. (March 2022)

• Record Type: Journal Article
• Authors: Murillo Alarcón, Roberto; Hertel, Tobias; François, Elise; Rahier, Hubert; Pontikes, Yiannis
• Is Part Of: Cement and concrete research. Volume 153(2022)
• Publication Date: 2022-03
• Subjects: Fe-rich slag -- Alkali-activated materials -- Porous materials -- Hydrothermal curing -- Autoclave -- Valorisation; Cement -- Periodicals; Cement -- Research -- Periodicals; Concrete -- Periodicals; Concrete -- Research -- Periodicals; Ciment -- Périodiques; Béton -- Périodiques; Cement; Concrete; Periodicals; 620.135
• DOI: 10.1016/j.cemconres.2021.106655
• Languages: English
• ISSNs: 0008-8846

Abstract

Abstract: This study provides insights on the formation of crystalline phases from Fe-rich slag-based porous inorganic polymers (porous IPs), cured under hydrothermal conditions. The porous IPs were synthesised using synthetic slags with different chemistries (from FeO-SiO2 -CaO to FeO-SiO2 -Al2 O3 -CaO systems) as solid precursors, and a sodium silicate-based alkaline activator. Chemical expansion was used to create the porous structure. After hardening, the porous monoliths were hydrothermally processed at different temperatures and respective steam pressures (150 °C, 4.8 bar; 200 °C, 15.5 bar and 250 °C, 39.7 bar) and for different durations (12–18 h). The presence of aluminium promoted the formation of the zeolite analcime within the first 12 h. The formation of crystalline calcium-silicate hydrates was promoted after a longer curing duration; however, just after the formation of analcime had taken place. Next to these phases, the Fe-rich smectite nontronite and calcium carbonates were detected. Highlights: Porous alkaline activated materials from synthetic Fe-rich slags. Formation of zeolite and C-S-H during hydrothermal curing Influence of the slag chemistry on the reaction products after hydrothermal curing Fe 3+ was found to partially replace Al +3 in the analcime structure.