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Influence of nano scale effects on the macroscopic rheology

  • Chemical admixtures like superplasticisers or stabilising agents are of ever increasing importance for modern concrete technology. They liberate the workability of concrete from its dependency on water content, and thus, open the gate towards innovative and future oriented concrete technologies. Meanwhile admixtures have become common practice in concrete technology, but the understanding of these highly complex polymers in the entire concrete system lags far behind their application. Due to its complex time-dependent, multi-phase and multi-scale behaviour, flowable concrete systems are highly complicated and cannot be described comprehensively by simple models. It is therefore extremely challenging to identify the relevant parameters that predominantly control flow phenomena on different size scales, since these may occur on any scale between the nano scale (e.g. superplasticizer adsorption) and macro scale (e.g. grading of the aggregates). The present study discusses fundamentalChemical admixtures like superplasticisers or stabilising agents are of ever increasing importance for modern concrete technology. They liberate the workability of concrete from its dependency on water content, and thus, open the gate towards innovative and future oriented concrete technologies. Meanwhile admixtures have become common practice in concrete technology, but the understanding of these highly complex polymers in the entire concrete system lags far behind their application. Due to its complex time-dependent, multi-phase and multi-scale behaviour, flowable concrete systems are highly complicated and cannot be described comprehensively by simple models. It is therefore extremely challenging to identify the relevant parameters that predominantly control flow phenomena on different size scales, since these may occur on any scale between the nano scale (e.g. superplasticizer adsorption) and macro scale (e.g. grading of the aggregates). The present study discusses fundamental mechanisms at the interface between particle or hydrate surfaces and the fluid phase at a very early stage of concrete formation, and links these effects to macroscopic flow phenomena. Based on the observations of the nano scale effects, it seems that higher sensitivity against variations in the constituents, the handling, or the boundary condition are the inevitable price for higher performances. However, eventually a very effective method is introduced that helps to maintain stable processes regardless of the root cause for performance changes based on an efficient in-situ process control scheme and superplasticizer and stabilising agents as counter actions.zeige mehrzeige weniger

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Metadaten
Autoren/innen:Wolfram Schmidt
Dokumenttyp:Vortrag
Veröffentlichungsform:Präsentation
Sprache:Englisch
Jahr der Erstveröffentlichung:2017
Organisationseinheit der BAM:7 Bauwerkssicherheit
7 Bauwerkssicherheit / 7.4 Baustofftechnologie
DDC-Klassifikation:Naturwissenschaften und Mathematik / Chemie / Analytische Chemie
Freie Schlagwörter:Admixtures; Cement; Ettringite; Meta materials; Nano engineering; Rheology
Themenfelder/Aktivitätsfelder der BAM:Analytical Sciences
Analytical Sciences / Oberflächen- und Grenzflächenanalytik
Veranstaltung:International Workshop on Nano-Engineered Meta-materials for Civil Infrastructures
Veranstaltungsort:Jinan, China
Beginndatum der Veranstaltung:20.5.2017
Enddatum der Veranstaltung:21.5.2017
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:17.07.2017
Referierte Publikation:Nein