1. Examination of physicochemical properties of organic coatings
applied on concrete
P.Pantazopoulou1, Th.Zafeiropoulou2, S.Kalogeropoulou1, E.Fountoukidis3, G. Batis2, K. Papadopoulos4
1. Electrical Engineering Department, Technological Educational Institute of Piraeus
2. Faculty of Chemical Engineering, National Technical University of Athens, Greece
3. Civil Engineering Department, Technological Educational Institute of Piraeus
4. Institute of Physical Chemistry, National Centre for Scientific Research, Demokritos,
Athens, Greece
eRA – 9, T.E.I. of Piraeus, September 2014

2. Results of the evaluation methods
Reinforcement’s corrosion behavior
Effect of UV-radiation to coatings
Liquid water and water vapor transmission rates
Carbonation depth
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3. Schematic diagram of Strain Gauges corrosion test set-up
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4. Corrosion protection evaluation of coated specimens by the SG method
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5. Corrosion protection evaluation by the SG method of coated specimens with corrosion inhibitor
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6. Laboratory SG corrosion test set-up
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7. Effect of UltraViolet-radiation to coatings
Radiation chamber
Radiation source: four F15W T8 BLB lamps
Radiation density: 71,7 μW·cm-2 (25 cm from the lamps)
Emission spectrum: peak wavelength of about λ=350 nm
Temperature during radiation: 36°C
Distance of radiated specimens from the lamps: 5 cm
UV-A radiation time: 1150 hours
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8. Coated specimens inside the radiation chamber during operation
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9. Photos of specimens before and after radiation
0 hours
400 hours
800 hours
1150 hours
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10. ISO 2409:1992(E) Cross-cut classification
Description
Surface appearance
The edges of the cuts are completely smooth; none of the squares of the lattice is detached ̶ 1
Detachment of small flakes of the coating at the intersections of the cuts. A cross-cut area not significantly greater than 5 % is affected. 2
The coating has flaked along the edges and/or at the intersections of the cuts. A cross-cut area significantly greater than 5 %, but not significantly greater than 15 %, is affected. 3
The coating has flaked along the edges of the cuts partly or wholly in large ribbons, and/or it has flaked partly or wholly on different parts of the squares. A cross-cut area significantly greater than 15 %, but not significantly greater than 35 %, is affected. 4
The coating has flaked along the edges of the cuts in large ribbons and/or some squares have detached partly or wholly. A cross-cut area significantly greater than 35 %, but not significantly greater than 65 %, is affected. 5
Any degree of flaking that cannot even be classified by classification 4.
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11. Cross-cut test results - Classification of specimens before and after radiation
Before radiation
After radiation
Coating
Before tape
After tape E P N 1 2 3 4 A 5 R
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12. Cross-cut test – Epoxy coated specimens
After tape
Before radiation
After radiation
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13. Cross-cut test – Acrylic emulsion specimens
After tape
Before radiation
After radiation
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14. BS EN ISO 4624:2003 Pull-off test - Classification of coatings
Result A
Cohesive failure of substrate
A/B
Adhesive failure between substrate and first coat B
Cohesive failure of first coat
B/C
Adhesive failure between first and second coats
-/Y
Adhesive failure between final coat and adhesive Y
Cohesive failure of adhesive
Y/Z
Adhesive failure between adhesive and test cylinder
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15. Breaking Strength (MPa)
Pull-off test results, Dry Film Thickness (DFT) and classification before radiation
Coating
Breaking Strength (MPa)
DFT (μm)
Classification E 7
400 Α P N 3
250
Α/Β 70% A 4
300
Α/Β 95% R
Α/Β 90%
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16. Breaking Strength (MPa)
Pull-off test results, Dry Film Thickness (DFT) and classification after radiation
Coating
Breaking Strength (MPa)
DFT (μm)
Classification E
1,5
400 Υ P 1 Α N 5 - A
300 R
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17. Photos of specimens before radiation and after pull-off test
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18. Photos of specimens after radiation and after pull-off test
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19. DIN EN 1062-3: Classification of liquid water permeability values
Liquid Water Transmission Rate w (kg/m2ˑh1/2)
I (high)
> 0,5
II (medium)
0,1 – 0,5
III (low)
< 0,1
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20. Mean values of water permeability measured for each organic coating
Liquid Water Transmission Rate (kg/m2ˑh1/2)
Classification DIN EN E
0,06
Class III (low) P
0,02 N
0,20
Class ΙΙ (medium) A
0,60
Class Ι (high) R
0,30
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21. Specimens for the measurements of liquid water permeability values
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22. EN ISO 7783-2 Classification of water vapor transmission rate values
Water Vapor Transmission Rate (g/(m2ˑd))
I (high)
> 150
II (medium)
15 – 150
III (low)
< 15
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23. Coated substrate for the water vapor transmission rate determination
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24. Mean values of water vapor transmission rate for each organic coating
Water Vapor Transmission Rate (g/m2ˑd)
Classification DIN EN ISO E 25
Class ΙΙ (medium) P 20 N
618
Class Ι (high) A
180 R
215
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25. Liquid water and water vapor transmission rate for all organic coatings
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26. Optimal behavior of organic coatings concerning water permeability and water vapor transmission rate
High water vapor transmission rate
Low water permeability
Coatings with these properties prevent the ingress of water and all the factors that water may carry while allowing the escape of water vapor from the interior of the wall creating a sealing membrane, which "breathes".
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27. Carbonation
Carbonation of concrete is due to the reaction of CO2 from the atmosphere with the Ca(OH)2 in the pore solution in the presence of moisture:
H2CΟ3 + Ca(OH)2 → CaCΟ3 +2Η2Ο
Carbonation
leads to reduction of the pH of the pore solution
makes the material less alkaline
results in reinforcement corrosion
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28. Carbonation depth measurements
Accelerated carbonation chamber conditions:
T:21±2°C, RH:60±10%, CO2 concentration: 1,0%,
total exposure time: 8 weeks
Carbonation depth (dk) is the average distance, measured in mm, from the surface of concrete, where the carbon dioxide (CO2) has reduced the alkalinity. A phenolophthalein indicator solution is used.
Carbonated mortar remains colorless.
Uncarbonated mortar is colored red-purple.
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29. Measurement of mortars’ carbonation depth
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30. Carbonation depth of mortars
Coating
Carbonation depth (mm)
4 weeks of exposure
8 weeks of exposure O 8 12 E 2 P 1 N
7,5
11,5 A 4
6,5 R 7 9
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31. Protection rate (%) of coatings against carbonation 8 weeks results
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32. Conclusions
Based on the above presented results an estimation of the properties related to the protection offered by the various organic coatings is made.
The protective action of all organic coatings against corrosion of the embedded reinforcement is confirmed.
According to the evaluated property differences on the effectiveness of each organic coating are revealed.
The simultaneous presence of the corrosion inhibitor improves the protective ability of coatings to various degrees.
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33. Acknowledgements
This research has been co-financed by the European Union (European Social Fund – ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: ARCHIMEDES III. Investing in knowledge society through the European Social Fund.
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34. Thank you for your attention!
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