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Thermo-mechanical and spalling behavior of normal weight and lightweight geopolymer concretes

  • The mechanical and microstructural properties of two geopolymer concretes, produced with either quartz aggregate or expanded clay aggregate, were assessed before, during and after high-temperature exposure up to 750 °C in order to better understand the engineering properties of the material. SEM investigations were also undertaken to better understand the observed changes in the mechanical properties. It was found that dehydration of capillary water caused micro-cracking and strength losses at temperatures ≤ 300 °C. At higher temperatures (T ≥ 500 °C) sintering promoted strength increases, leading significant strength advantages over conventional concretes. Stress-mechanical strain curves, which are the basis of the fire design of concrete structures, were determined. In addition, the two geopolymer concretes where exposed to the ISO 834-1 standard fire curve in a small-scale spalling test set-up. Acoustic emission measurements during, and acoustic measurements and optical microscopyThe mechanical and microstructural properties of two geopolymer concretes, produced with either quartz aggregate or expanded clay aggregate, were assessed before, during and after high-temperature exposure up to 750 °C in order to better understand the engineering properties of the material. SEM investigations were also undertaken to better understand the observed changes in the mechanical properties. It was found that dehydration of capillary water caused micro-cracking and strength losses at temperatures ≤ 300 °C. At higher temperatures (T ≥ 500 °C) sintering promoted strength increases, leading significant strength advantages over conventional concretes. Stress-mechanical strain curves, which are the basis of the fire design of concrete structures, were determined. In addition, the two geopolymer concretes where exposed to the ISO 834-1 standard fire curve in a small-scale spalling test set-up. Acoustic emission measurements during, and acoustic measurements and optical microscopy after heat exposure were employed to investigate crack formation during the tests. Both concretes did not spall, which is attributed to their comparatively high permeability and their low amount of chemically bound water. Significant crack formation was detected only around the temperature of the α–β quartz transition (573 °C) and on cooling. Because of aggregate deformations at the quartz transition temperature, deterioration after heating was more significant in the geopolymer concrete with quartz aggregates. Crack formation occurred also in the concrete with expanded clay aggregates, presumably caused by shrinkage of the geopolymer paste on cooling.zeige mehrzeige weniger

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  • 2016_ACCTA_TM Spalling GPC_neu - Publica.pdf
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Metadaten
Autor*innen:Gregor GluthORCiD
Koautor*innen:W.D.A. Rickard, Klaus Pistol, Steve Werner, Stephan Pirskawetz
Dokumenttyp:Vortrag
Veröffentlichungsform:Präsentation
Sprache:Englisch
Jahr der Erstveröffentlichung:2016
DDC-Klassifikation:Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurbau
Freie Schlagwörter:Concrete; Geopolymers; Heat exposure; Spalling; Transient thermal creep
Veranstaltung:Advances in Cement and Concrete Technology in Africa (ACCTA 2016)
Veranstaltungsort:Dar es Salaam, Tanzania
Beginndatum der Veranstaltung:27.01.2016
Enddatum der Veranstaltung:29.01.2016
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:21.07.2016
Referierte Publikation:Nein
Eingeladener Vortrag:Nein
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