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| Titel |
The behavior of biogenic silica-rich rocks and volcanic tuffs as pozzolanic additives in cement |
| VerfasserIn |
Dimitris Fragoulis, Michael Stamatakis, Marianthi Anastasatou |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250114780
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| Publikation (Nr.) |
 EGU/EGU2015-15595.pdf |
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| Zusammenfassung |
| Cements currently produced, include a variety of pozzolanic materials, aiming for lower
clinker addition and utilization of vast deposits of certain raw materials and/or mining
wastes and byproducts. The major naturally occurring pozzolanic materials include
glassy tuffs, zeolitic tuffs, diatomites and volcanic lavas rich in glassy phase, such as
perlites. Therefore, based on the available raw materials in different locations, the
cement composition might vary according to the accessibility of efficient pozzolanic
materials.
In the present investigation, the behavior of pozzolanic cements produced with
representative samples of the aforementioned materials was studied, following the
characterization of the implemented pozzolanas with respect to their chemical and
mineralogical characteristics.
Laboratory cements were produced by co-grinding 75% clinker, 5% gypsum and 20%
pozzolana, for the same period of time (45 min). Regarding pozzolanic materials, four
different types of pozzolanas were utilized namely, diatomite, perlite, zeolite tuff and glassy
tuff. More specifically, two diatomite samples originated from Australia and Greece, with
high and low reactive silica content respectively, two perlite samples originated from Turkey
and from Milos Island, Greece, with different reactive silica contents, a zeolite tuff
sample originated from Turkey and a glassy tuff sample originated from Milos Island,
Greece.
The above pozzolana samples, which were ground in the laboratory ball mill for cement
production performed differently during grinding and that was reflected upon the specific
surface area (cm2/gr) values. The perlites and the glassy tuff were the hardest to grind,
whereas, the zeolite tuff and the Australian diatomite were the easiest ones. However, the
exceedingly high specific surface area of the Australian diatomite renders cement difficult to
transport and tricky to use for concrete manufacturing, due to the high water demand of the
cement mixture.
Regarding late compressive strength, the worst performing cement was the one with the
lowest reactive silica content with biogenic opal-A as the only reactive pozzolana constituent.
Cements produced with perlites, raw materials consisting mainly of a glassy phase, were
characterized by higher strength and a rather ordinary specific surface area. Cements
produced with Turkish zeolite tuff and Milos glassy tuff exhibited higher late compressive
strength than those mentioned above. The highest strength was achieved by the
implementation of Australian diatomite for cement production. Its 28 day strength
exceeded that of the control mixture consisting of 95% clinker and 5% gypsum. That
could be attributed to both, high specific surface of cement and reactive SiO2 of
diatomite.
Therefore, a preliminary assessment regarding late strength of pozzolanic cements could
be obtained by the consideration of two main parameters, namely: specific surface area of
cement and reactive silica content of pozzolana. |
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