Microstructure analysis of thermally treated ultra high performance concrete in the context of the durability performance

  • Ultra high performance concrete (UHPC) is known for its high compressive strength of more than 150 MPa and its high durability. Thermal treatment at 90°C can accelerate the strength development so that the 28-days-strength can be achieved immediately after the treatment and an additional increase up to 30 % in some cases. The reason for the strength development is an accelerated hydration of the clinker minerals and an intensified pozzolanic reaction leading to a denser microstructure. In previous research inhomogeneities in form of a zonation after unprotected thermal treatment were observed and analysed in respect to changes in the microstructure. This zonation is defined by a different microstructure in the core compared to the outer zone in the matter of porosity, mineral phase composition and a significant change in the potassium and sulphur concentration of the zones is measurable. To isolate different transport mechanisms responsible for these element distributions UHPCUltra high performance concrete (UHPC) is known for its high compressive strength of more than 150 MPa and its high durability. Thermal treatment at 90°C can accelerate the strength development so that the 28-days-strength can be achieved immediately after the treatment and an additional increase up to 30 % in some cases. The reason for the strength development is an accelerated hydration of the clinker minerals and an intensified pozzolanic reaction leading to a denser microstructure. In previous research inhomogeneities in form of a zonation after unprotected thermal treatment were observed and analysed in respect to changes in the microstructure. This zonation is defined by a different microstructure in the core compared to the outer zone in the matter of porosity, mineral phase composition and a significant change in the potassium and sulphur concentration of the zones is measurable. To isolate different transport mechanisms responsible for these element distributions UHPC samples were thermally treated at 90 °C and the microstructure was investigated under dry conditions and after immersion in water to investigate the influence of dehydration during and rehydration after the thermal treatment on the microstructure. Through durability testing via water absorption, water vapour diffusion, permeability testing and sulfuric acid resistance transport mechanisms like diffusion, migration, capillary suction are under investigation in correlation with the microstructure analysis. For the microstructure analysis measurements with µXRF, mercury intrusion porosity, XRD and SEM were conducted.zeige mehrzeige weniger

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Metadaten
Autoren/innen:Marieke Voigt, Julia von Werder, Birgit Meng
Persönliche Herausgeber/innen:B. Middendorf, E. Fehling
Dokumenttyp:Beitrag zu einem Tagungsband
Veröffentlichungsform:Verlagsliteratur
Sprache:Englisch
Titel des übergeordneten Werkes (Englisch):Schriftenreihe Baustoffe und Massivbau: Ultra-High Performance Concrete and High Performance Materials
Jahr der Erstveröffentlichung:2020
Organisationseinheit der BAM:7 Bauwerkssicherheit
7 Bauwerkssicherheit / 7.1 Baustoffe
Herausgeber (Institution):Universität Kassel
Verlag:Kassel University Press
Verlagsort:Kassel
Jahrgang/Band:23
Erste Seite:151
Letzte Seite:152
DDC-Klassifikation:Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurwissenschaften und zugeordnete Tätigkeiten
Freie Schlagwörter:Durability; Thermal treatment; Transport mechanism; UHPC; Zonation
Themenfelder/Aktivitätsfelder der BAM:Material
Material / Degradation und Life Cycle von Werkstoffen
Material / Materialien und Stoffe
Veranstaltung:HiPerMat 2020
Veranstaltungsort:Kassel, Germany
Beginndatum der Veranstaltung:11.03.2020
Enddatum der Veranstaltung:13.03.2020
DOI:https://doi.org/10.17170/kobra-202002271026
ISBN:978-3-7376-0828-2
Zugehöriger Identifikator:https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/52375
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:01.04.2021
Referierte Publikation:Nein