Das Suchergebnis hat sich seit Ihrer Suchanfrage verändert. Eventuell werden Dokumente in anderer Reihenfolge angezeigt.
  • Treffer 5 von 42
Zurück zur Trefferliste

Effect of the storage of cement on early properties of cementitious systems

  • As soon as cement is mixed with water, the hydration reaction starts to set of. The progression of the hydration process is governed by the amount and the availability of water and its possibility to access the unhydrated cement grain surfaces. For a total hydration cement theoretically requires water amounting approximately 0.38 of its own mass. Nevertheless, due to the cement’s highly hygroscopic nature, already the moisture in the ambient air can cause first hydration reactions to set in upon the cement grain surfaces. Such pre-hydration processes have an effect on the cement's properties. Dpending on the specific conditions during the storage the significance of the impact on certain properties can vary. If cement is consumed soon after production and is transported only short distances in a silo wagon to its final destination for immediate use without further stock transfer, the effects are rather negligible. However, if cement is delivered in bags, transported over longAs soon as cement is mixed with water, the hydration reaction starts to set of. The progression of the hydration process is governed by the amount and the availability of water and its possibility to access the unhydrated cement grain surfaces. For a total hydration cement theoretically requires water amounting approximately 0.38 of its own mass. Nevertheless, due to the cement’s highly hygroscopic nature, already the moisture in the ambient air can cause first hydration reactions to set in upon the cement grain surfaces. Such pre-hydration processes have an effect on the cement's properties. Dpending on the specific conditions during the storage the significance of the impact on certain properties can vary. If cement is consumed soon after production and is transported only short distances in a silo wagon to its final destination for immediate use without further stock transfer, the effects are rather negligible. However, if cement is delivered in bags, transported over long distances, shifted serval times and stored for longer time periods until it is finally consumend, these effects can be quite severe. Due to the actual logistical situation with comparably few cement plants, large delivery distances and partially less developed infrastructures, the latter scenario pictures the situation for the most cases in Africa quite well. In order to verify the relevance of the pre-hydation for practical application, a series of tests was conducted at the German Federal Institute for Materials Research and Testing (BAM). The influence of the cement storage on gresh and hardened concrete properties was investigated for different concrete and mortar types. The investigations show that the impact of the storage conditions is more pronounced for specialized concretes with high sophisticated optimized mixture compositions containing admixtures. Nevertheless, the effects also occur for ordinary concrete and should not be ignored.zeige mehrzeige weniger

Volltext Dateien herunterladen

  • ACCTA2013-ISBN978-3-9815360-3-4-Storageconditions.pdf
    eng

Metadaten exportieren

Weitere Dienste

Teilen auf Twitter Suche bei Google Scholar
Metadaten
Autoren/innen:Peter Ramge, Wolfram Schmidt, Hans-Carsten Kühne
Persönliche Herausgeber/innen:H.C. Uzoegbo, Wolfram Schmidt
Dokumenttyp:Beitrag zu einem Tagungsband
Veröffentlichungsform:Eigenverlag BAM
Sprache:Englisch
Titel des übergeordneten Werkes (Englisch):ACCTA - International conference on advances in cement and concrete technology in Africa 2013 (Proceedings)
Jahr der Erstveröffentlichung:2013
Organisationseinheit der BAM:7 Bauwerkssicherheit
7 Bauwerkssicherheit / 7.4 Baustofftechnologie
Herausgeber (Institution):Bundesanstalt für Materialforschung und -prüfung (BAM)
Erste Seite:339
Letzte Seite:347
Freie Schlagwörter:Ambient conditions; Atmospheric humidity; Cement; Hydration; Pre-hydration; Storage
Veranstaltung:ACCTA - International conference on advances in cement and concrete technology in Africa 2013
Veranstaltungsort:Johannesburg, South Africa
Beginndatum der Veranstaltung:28.01.2013
Enddatum der Veranstaltung:30.01.2013
ISBN:978-3-9815360-3-4
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:20.02.2016
Referierte Publikation:Nein