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Calorimetry Study of the Influence of Portland Cement Content, Slag/Fly Ash Ratio, and Activator Type on the Early Hydration of Hybrid Cements

  • Hybrid cements (cements composed of Portland clinker, supplementary cementitious materials and an alkaline activator) potentially combine advantages of conventional cements with those of alternative binders, such as low heat of hydration and improved durability in some environments. While fly ash-based hybrid cements have been studied in considerable detail, slag-dominated hybrid cements appear to have received less attention. Here, the latter materials have been studied by isothermal calorimetry, X-ray diffraction and strength testing. The heat of hydration of these cements was as low as ~50% of that of an ordinary Portland cement, while their strength after 28-day curing was in the range 31–61 MPa. The phase assemblages after 28-day curing depended on the activator, with Na2SO4 leading to ettringite and Na2CO3 leading to hemicarbonate formation, respectively, besides C–A–S–H, portlandite and hydrotalcite. The U phase was identified when a high Na2SO4 dose and/or fly ash was employed.Hybrid cements (cements composed of Portland clinker, supplementary cementitious materials and an alkaline activator) potentially combine advantages of conventional cements with those of alternative binders, such as low heat of hydration and improved durability in some environments. While fly ash-based hybrid cements have been studied in considerable detail, slag-dominated hybrid cements appear to have received less attention. Here, the latter materials have been studied by isothermal calorimetry, X-ray diffraction and strength testing. The heat of hydration of these cements was as low as ~50% of that of an ordinary Portland cement, while their strength after 28-day curing was in the range 31–61 MPa. The phase assemblages after 28-day curing depended on the activator, with Na2SO4 leading to ettringite and Na2CO3 leading to hemicarbonate formation, respectively, besides C–A–S–H, portlandite and hydrotalcite. The U phase was identified when a high Na2SO4 dose and/or fly ash was employed. Na2SO4 accelerated the early reaction of the Portland clinker, while Na2CO3 appeared to decrease the extent of reaction of the clinker and led to a shift of the second hydration peak (likely related to slag reaction) to later hydration times, as did substitution of slag by fly ash. Increasing Na2SO4 dose from 4 to 6% did not lead to further acceleration of hydration or improved strength.zeige mehrzeige weniger

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Metadaten
Autor*innen:Gregor GluthORCiD, S. Garel
Persönliche Herausgeber*innen:I. B. Valente, A. Ventura Gouveia, S. S. Dias
Dokumenttyp:Beitrag zu einem Tagungsband
Veröffentlichungsform:Verlagsliteratur
Sprache:Englisch
Titel des übergeordneten Werkes (Englisch):Proceedings of the 3rd RILEM Spring Convention and Conference (RSCC 2020) – Volume 2: New Materials and Structures for Ultra-durability
Jahr der Erstveröffentlichung:2021
Organisationseinheit der BAM:7 Bauwerkssicherheit
7 Bauwerkssicherheit / 7.4 Baustofftechnologie
Verlag:Springer
Verlagsort:Cham
Erste Seite:217
Letzte Seite:226
DDC-Klassifikation:Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Angewandte Physik
Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurbau
Freie Schlagwörter:Alkali-activated materials; Calorimetry; Early hydration; Hybrid cements
Themenfelder/Aktivitätsfelder der BAM:Energie
Energie / Kerntechnische Entsorgung
Infrastruktur
Veranstaltung:3rd RILEM Spring Convention and Conference (RSCC 2020)
Veranstaltungsort:Guimarães, Portugal
Beginndatum der Veranstaltung:10.03.2020
Enddatum der Veranstaltung:14.03.2020
DOI:10.1007/978-3-030-76551-4_20
ISBN:978-3-030-76550-7
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:09.08.2021
Referierte Publikation:Nein
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