Cured cuttlebone/chitosan-heated clay composites: Microstructural characterization and practical performances

• Published in: Journal of Building Engineering 2019-11, Vol.26, p.100872, Article 100872
• Main Authors: Mourak, Abdellah, Hajjaji, Mohamed, Alagui, Abdelhakim
• Format: Article
• Language: English
• Subjects: Alkali-activation; Chitosan; Cuttlebone; Heated clay; Microstructure
• ISSN: 2352-7102; 2352-7102
• DOI: 10.1016/j.jobe.2019.100872

Clay-based materials composed of geopolymers and natural fibbers, among others, could be suitable composites for building construction. So, in this study, composites of a heated kaolinitic-illitic clay and cuttlebone or chitosan (up to 10 mass%) were etched with a NaOH solution (6 M), shaped as briquettes and cured at 83 °C for up to 30 days. The microstructure of the cured composites was investigated, and some of their practical performances were evaluated. The results showed that metakaolinite and illite - to some extent-, and a portion of Na+ ions were involved in the formation of zeolite (chabazite) and Na-carbonate respectively. Moreover, layers of cuttlebone or chitosan were built up around the clay particles, and the thick layers developed in the cuttlebone- and in the chitosan-rich composites affected differently the zeolization process. Chitosan versus cuttlebone favoured zeolization by facilitating the ions mobility, and the illite reactivity. By referring to the mechanical/physical properties of the cured NaOH-etched heated clay, the bending and the compressive strengths of the cured composites as well as their water absorption increased by two-to three times. The strengthening of the composites was related mainly to the reduction of porosity (up to 40% for the cuttlebone-rich composite). [Display omitted] •Chabazite and Na-carbonate formed in both cured composites.•The zeolization process was altered by the clay particles coating.•Chitosan facilitated the ions mobility, and the reactivity of the illite and metakaolinite.•The mechanical strengths of the cured composites increased by two-to three times.•The evolutions of the main practical performances were related chiefly to the porosity.