Pozzolanic Activity Assessment of Fl A h (A USA)f Fly...
Transcript of Pozzolanic Activity Assessment of Fl A h (A USA)f Fly...
Pozzolanic Activity Assessment f Fl A h (A USA)of Fly Ashes (Argos USA)
Anna Maria Workshop XII2011/11/09Argos I&DDaniel DuqueCarlos A. Orozco
Objectives• Identify the best parameters to asses fly ashes pozzolanic activity.
– The evaluation of the pozzolanic activity was carried out using three different techniques:
Compressive strength test Calorimetry Thermogravimetry
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Compressive strength on mortars
Straight cement:: 33.5 MPa Straight cement:: 39.4 MPa
• Top 3:Straight cement:: 44.8 MPa
• Top 3:– Fly ash 1– Fly ash 3
Fl h 5– Fly ash 5
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Materials – Chemical composition
• Cement type IFl h 1 2 3 d 4 Cl F fl h 5 Cl C• Fly ash 1, 2, 3 and 4: Class F, fly ash 5: Class C
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Materials – Physical properties
Fly ash d80 (um)Retained on
325 sieve (%)
Specific
surface m2/g
Cement 32 44 0 844Cement 32.44 - 0.844
Fly Ash 1 49.10 16.3 0.919
Fly Ash 2 97.10 22.1 0.396
Fly Ash 3 42.76 18.0 0.590Fly Ash 3 42.76 18.0 0.590
Fly Ash 4 64.76 18.8 0.434
Fly Ash 5 49.10 15.6 0.954
• Fly ashes 1, 3 and 5 have the bigger specific surfaces.
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Calorimetry: released heat during hydration80% - 20% 65% - 35%
50% - 50%
• Fly ash 5 (Class C) released the• Fly ash 5 (Class C) released the higher amount of heat for all 3 proportions.
• Almost same behavior for the other 4• Almost same behavior for the other 4.
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Thermogravimetry: Portlandite consumption and hydrates
26%
31%on
(%)
Fly ash 1 Fly ash 2 Fly ash 3 Fly ash 4 Fly ash 5
21%
26%
nic
reac
tio
16%
by p
ozzo
la
6%
11%
nsum
ed b
1%
80% - 20% 65%-35% 50%-50%a(O
H)2
co
• Fly ashes 1, 3 and 5 present the bigger consumption of Portlandite
-4%80% - 20% 65%-35% 50%-50%C
a
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Thermogravimetry: Portlandite consumption and hydrates
80% - 20%
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Thermogravimetry: Portlandite consumption and hydrates
65% 35%65% - 35%
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Thermogravimetry: Portlandite consumption and hydrates
50% - 50%
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Thermogravimetry: comments
• Increasing the replacement percentage of fly ash generates various kinds of hydrates but at the same timegenerates various kinds of hydrates but at the same time there quantity is reduced.
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Conclusions
• Portlandite consumption and hydrates generation seems to be the most effective way to identified fly ashes with highbe the most effective way to identified fly ashes with high replacement potential.
• Fly ash 1 and 5 generates the biggest amount of hydrates.Fly ash 1 and 5 generates the biggest amount of hydrates.• Medium and high calcium fly ashes present better
performances for high replacements.p g p• Low LOI and high specific surfaces are recommended.
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