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Screening-tests on the susceptibility to spalling of two ordinary concretes

  • Investigating the spalling behaviour of a concrete mixture using large scale members is complex and expensive. Thus, the susceptibility of concrete to spalling is investigated by means of fire tests on small scale specimens. However, the reduction of the fire exposed surface increases the influence of boundary effects. Macrocracking and the water loss via the lateral surfaces reduce the impact of the thermomechanical and thermohydraulic damage mechanisms and therefore, lower the risk of spalling. Thus, the influence of different restraints on the spalling behaviour of intermediate scaled specimens (Ø=0.47 m; h=0.29 m) was investigated for two ordinary concrete mixtures. Both mixtures had the same composition except the type of aggregate. One mixture contained only quartzitic aggregates, whereas the other mixture was made with basalt grit as coarse aggregates. Applied steel rings restrained the thermal expansion of the specimen and prevented the loss of water, whereas applied steelInvestigating the spalling behaviour of a concrete mixture using large scale members is complex and expensive. Thus, the susceptibility of concrete to spalling is investigated by means of fire tests on small scale specimens. However, the reduction of the fire exposed surface increases the influence of boundary effects. Macrocracking and the water loss via the lateral surfaces reduce the impact of the thermomechanical and thermohydraulic damage mechanisms and therefore, lower the risk of spalling. Thus, the influence of different restraints on the spalling behaviour of intermediate scaled specimens (Ø=0.47 m; h=0.29 m) was investigated for two ordinary concrete mixtures. Both mixtures had the same composition except the type of aggregate. One mixture contained only quartzitic aggregates, whereas the other mixture was made with basalt grit as coarse aggregates. Applied steel rings restrained the thermal expansion of the specimen and prevented the loss of water, whereas applied steel sheet primarily reduced the loss of water during the fire test. Additionally, the fire exposed surface of one specimen of each mixture was pre-dried under controlled climate conditions and fire tested with applied steel rings. The results show a higher spalling volume for the ring restrained specimens compared to the other covering types. Further, the pre-dried boundary zone leads to delayed and decreased occurrence of spalling compared to the non-dried specimens for the concrete with quartzitic aggregates and to a prevention of spalling for the mixture with basalt aggregates. Additionally, the results show that the influence of the thermomechanical behaviour of the coarse aggregates increases with increasing restraint. The restrained conditions of the specimens with applied steel ring are comparable to the conditions in the centre of a large scale member. This test series is a further step for possible concept of steel ring restraint concrete specimens as “screening-tests” in upcoming projects.zeige mehrzeige weniger

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Autor*innen:André Klimek, Ludwig StelznerORCiD, Sascha HothanORCiD, J. Zehfuß
Dokumenttyp:Beitrag zu einem Tagungsband
Veröffentlichungsform:Eigenverlag BAM
Sprache:Englisch
Titel des übergeordneten Werkes (Englisch):7th international workshop on concrete spalling due to fire exposure - Proceedings
Jahr der Erstveröffentlichung:2022
Organisationseinheit der BAM:7 Bauwerkssicherheit
7 Bauwerkssicherheit / 7.3 Brandingenieurwesen
Verlag:Bundesanstalt für Materialforschung und -prüfung (BAM)
Verlagsort:Berlin
Erste Seite:15
Letzte Seite:24
DDC-Klassifikation:Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurbau
Freie Schlagwörter:Concrete; Fire test; Restraint; Spalling
Themenfelder/Aktivitätsfelder der BAM:Infrastruktur
Infrastruktur / Fire Science
Veranstaltung:IWCS 2022
Veranstaltungsort:Berlin, Germany
Beginndatum der Veranstaltung:12.10.2022
Enddatum der Veranstaltung:14.10.2022
Zugehöriger Identifikator:https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/56079
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:19.10.2022
Referierte Publikation:Nein
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