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Factors influencing thermal conductivity and compressive strength of natural fiber-reinforced geopolymer foams

  • New sustainable, environmentally friendly materials for thermal insulation of buildings are necessary to reduce their carbon footprints. In this study, Miscanthus fiber-reinforced geopolymer composites, foamed with sodium dodecyl sulfate (SDS), were developed using fly ash as a geopolymer precursor. The effects of fiber content, fiber size, curing temperature, foaming agent content, fumed silica specific surface area and fumed silica content on thermal conductivity and compressive strength were evaluated using a Plackett-Burman design of experiment. Furthermore, the microstructure of geopolymer composites was investigated using X-ray diffraction (XRD), X-ray micro-computed tomography (μCT) and scanning electron microscopy (SEM). The measured characteristic values were in the following ranges: Thermal conductivity 0.057 ​W ​(m ​K)−1 to 0.127 ​W ​(m ​K)−1, compressive strength 0.007 ​MPa–0.719 ​MPa and porosity 49 ​vol% to 76 ​vol%. The results reveal an enhancement of thermal conductivity by elevated fiber size and foaming agent content. In contrast, the compressive strength is enhanced by high fiber content. Additionally, SEM images indicate a good interaction between the fibers and the geopolymer matrix, because nearly the whole fiber surface is covered by the geopolymer.

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Document Type:Article
Author:Katharina Walbrück, Lisabeth Drewler, Steffen Witzleben, Dietmar Stephan
Parent Title (English):Open Ceramics
Issue:March 2021
Article Number:100065
Place of publication:Amsterdam
Publishing Institution:Hochschule Bonn-Rhein-Sieg
Date of first publication:2021/01/31
Copyright:© 2021 Published by Elsevier Ltd on behalf of European Ceramic Society.
Funding Information:This work was supported by the European Regional Development Fund [Grant No. EFRE 0500035] and the German Federal Ministry of Education and Research [Grant No. 13FH158IN6].
Keyword:Compressive strength; Fiber reinforcement; Foaming; Geopolymer; Miscanthus; Thermal conductivity
Departments, institutes and facilities:Fachbereich Angewandte Naturwissenschaften
Projects:FHInvest 2016: Feldemissions-Elektronenmikroskop mit Computertomographie-System für Materialentwicklungen und Sicherheitstechnologien (DE/BMBF/13FH158IN6)
Biobasierte Produkte (EFRE/0500035)
Dewey Decimal Classification (DDC):6 Technik, Medizin, angewandte Wissenschaften / 66 Chemische Verfahrenstechnik / 660 Chemische Verfahrenstechnik
Entry in this database:2021/02/04
Licence (German):License LogoCreative Commons - CC BY-NC-ND - Namensnennung - Nicht kommerziell - Keine Bearbeitungen 4.0 International