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VABOR bijeenkomst 22 maart 2012 Nebest Adviesgroep Mijdrecht - Nederland

Lezing: Feasibility of externally bonded reinforcement for cathodic protection Philippe De Schoesitter Op uitnodiging van de Vereniging Adviseurs Beton Onderhoud en Reparatie (VABOR). VABOR bijeenkomst 22 maart 2012 Nebest Adviesgroep Mijdrecht - Nederland.

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VABOR bijeenkomst 22 maart 2012 Nebest Adviesgroep Mijdrecht - Nederland

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  1. Lezing: Feasibility of externallybondedreinforcementfor cathodic protectionPhilippe De SchoesitterOp uitnodiging van de Vereniging Adviseurs Beton Onderhoud en Reparatie (VABOR) VABOR bijeenkomst 22 maart 2012 Nebest Adviesgroep Mijdrecht- Nederland

  2. Feasibility of externallybonded CFRP for cathodic protection Promotoren Prof. dr. ir. S. Matthys, Prof. dr. ir. G. De Schutter Begeleidster Ir. D. ErtzibengoaGaztelumendi Vakgroep Bouwkundige Constructies Voorzitter: prof. dr. ir. L. Taerwe Faculteit ingenieurswetenschappen en Architectuur Academiejaar 2010-2011 Hoofdstuk 1: Corrosie van wapeningsstaal in beton en kathodische bescherming Hoofdstuk 2: Uitwendig verlijmde carbonvezelwapening (CFRP) Hoofdstuk 3: Experiment en toetsing haalbaarheid VABOR bijeenkomst - Philippe de Schoesitter

  3. 1. Corrosie en kathodische bescherming (ICCP) 1.1 Corrosieproces en electrochemische achtergrond 1.2 Corrosiesnelheidsmeting 1.3 Kathodische bescherming: concrete toepassing VABOR bijeenkomst - Philippe de Schoesitter

  4. 1.2 Corrosieproces Fe2+ VABOR bijeenkomst - Philippe de Schoesitter

  5. VABOR bijeenkomst - Philippe de Schoesitter

  6. 1.2 Corrosiesnelheidsmeting Tafel-slopemeasurement Lineaire polarisatie VABOR bijeenkomst - Philippe de Schoesitter

  7. 1.3 Kathodische bescherming concreet • Mesh • Draad • Strip + coating (mortal, acryl…) Materials: • Metaal (Pt, Ti, Ag, Ni …) • Carbon (graphite …) VABOR bijeenkomst - Philippe de Schoesitter

  8. 2. “CFRP EBR” CFRP = Carbon FibreReinforcedPolymer EBR = ExternallybondedReinforcement 2.1 Wat, hoe en waarom? 2.2 Mogelijkheid tot combinatie met K.B. -> geleidbaarheid van carbon -> overlap toepassingsgebied 2.3 Probleem: geleidbaarheid lijmmiddel VABOR bijeenkomst - Philippe de Schoesitter

  9. 2.1 CFRP EBR VABOR bijeenkomst - Philippe de Schoesitter

  10. 2.1 CFRP EBR VABOR bijeenkomst - Philippe de Schoesitter

  11. 2.1 CFRP EBR VABOR bijeenkomst - Philippe de Schoesitter

  12. 2.2 Toepassing van CFRP als anode-materiaal • Interesse in combinatie vanuit verschillende perspectieven: • CFRP EBR heeft positieve invloed op corrosie (zgn. “passieve bescherming”) • Sterke geleidbaarheid van carbonvezels: eis van 1Ω.cm ruimschoots voldaan • De toepassingsgebieden van aanbreng externe wapening en • kathodische bescherming (of preventie) vertonen enige overlap. • I.h.b. wanneer grote betonoppervlakken onder trekspanning extra wapening vergen VABOR bijeenkomst - Philippe de Schoesitter

  13. 2.3 Geleidbaarheid epoxy-lijm Epoxy is insulative  conductiveadhesive  additives in epoxy: - Metal - Carbon particles: >‘Carbon black’ (powder) >graphite (fibres) >nanotubes VABOR bijeenkomst - Philippe de Schoesitter

  14. 2.3 Geleidbaarheid epoxy-lijm: Carbon Black - smallconductiveparticles - form a 3D-network as ‘electronpath’ + tunnel effect - chemicallyrather inert, temperatureresistant - “thresholdconcentration” - very high surfacearea (6 to 1500 m²/g) = problem! Coville NJ, Mhlanga SD, Nxumalo EN, Shaikjee A. A review of shaped carbon nanomaterials. S Afr J Sci. 2011;107(3/4), Art. #418, 15 pages. DOI: 10.4102/ sajs.v107i3/4.418 VABOR bijeenkomst - Philippe de Schoesitter

  15. 3. Experiment en toetsing haalbaarheid 3.1 Experiment set-up and program 3.2 Results and discussion 3.3 Conclusion VABOR bijeenkomst - Philippe de Schoesitter

  16. 3. Experiment en toetsing haalbaarheid 3.1 Experiment set-up and program 3.2 Results and discussion 3.3 Conclusion VABOR bijeenkomst - Philippe de Schoesitter

  17. 3.1 Experiment set-up and program Lollypop specimens: h=100mm, D≈50mm, reinforcement bar d=10mm Mortarcomposition:  C:SAND = 1:3  W/C = 0,65  Cl-/C = 4,25 wt% WET LAY-UP CFRP wraps: CP-ax-… : CFRP wrapsaxialfibredirections CP-rad-…: CFRP wrapsradialfibredirection CP-…: wrapsconsists of epoxy adhesiveonly VABOR bijeenkomst - Philippe de Schoesitter

  18. 3.1 Experiment set-up and program Primary anode: forconnec-tion to DC power supply and current spread over anode surface Axialfibredirection: optimalcurrent spread throughfibres (expected), “Ax-…” specimens Radialfibredirection: worsecurrent spread expected (bad conductivity of fibres in transversaldirection), “Rad-…” specimens VABOR bijeenkomst - Philippe de Schoesitter

  19. 3.1 Experiment set-up and program CP/immersion program Acceleratedcorrosioninitiation and process:  initial chloride content (4,25wt%)  cyclicimmersion in saline water (1wt%) CP program: phase 1: 14 days58,35mA/m² phase 2: 14 days26,53mA/m² VABOR bijeenkomst - Philippe de Schoesitter

  20. 3.1 Experiment set-up and program Conductive epoxies: VABOR bijeenkomst - Philippe de Schoesitter

  21. 3.1 Experiment set-up and program Serial circuit  equalprotectioncurrent! Separate baths nocurrent loss through water! VABOR bijeenkomst - Philippe de Schoesitter

  22. 3.1 Experiment set-up and program Reference specimens: “Ref”: cyclicimmersionbutunprotected (CP) Ref-1,2,3:no CFRP wrap Ref-FRP: classic resistantCFRP wrap Tafel: notimmersed, unprotected (CP) Tafel-ref: nowrap Tafel-50298: wrap VABOR bijeenkomst - Philippe de Schoesitter

  23. 3. Experiment en toetsing haalbaarheid 3.1 Experiment set-up and program 3.2 Results and discussion 3.3 Conclusion VABOR bijeenkomst - Philippe de Schoesitter

  24. 3.2 Results and discussion CP and Ref specimens  LinearPolarization (a) After 14 days CP/imm. (b) After 28 days CP/imm. CP switchedoff 48h in advance Ecorr±20mV and 0,15mV/s Tafel specimens  Potentiodynamicmeas. Tafel extrapolationforIcorr SlopemeasurementsforB Cell set-up VABOR bijeenkomst - Philippe de Schoesitter

  25. 3.2 Results and discussion VABOR bijeenkomst - Philippe de Schoesitter

  26. 3.2 Results and discussion VABOR bijeenkomst - Philippe de Schoesitter

  27. 3.2 Results and discussion VABOR bijeenkomst - Philippe de Schoesitter

  28. 3.2 Results and discussion VABOR bijeenkomst - Philippe de Schoesitter

  29. 3.2 Results and discussion On average and compared to Ref specimens: AX-specimens: 56% Rad-specimens: 53% CP-specimens: 64% 60L specimens: 53% 57C specimens: 71% 64C specimens: 51% 50298 specimens: 68% ECC specimens: 61% Epo specimens: 44% lowercorrosionrates VABOR bijeenkomst - Philippe de Schoesitter

  30. 3.2 Results and discussion Icorrevolution: VABOR bijeenkomst - Philippe de Schoesitter

  31. 3.2 Results and discussion Tafel slopemeasurements: B ≈ 26mV (depassivated steel) GoodcorrelationwithIcorrfromLP-measurements Mass loss measurements: CorrelationwithIcorrfromLP-measurements (withinexpected factor 2 error) VABOR bijeenkomst - Philippe de Schoesitter

  32. 3.2 Results and discussion • The steel potentials are not found in the safe passive zone • -> influence added chloride • Iprotdecrease (from 0,11 to 0,05mA) results in potential increase • -> except: fibreless specimens • Active chloride corrosion initiation was not prevented, but ICCP was effective. • > influence added chloride • The radial fibre orientation gives the most consistent results. • >This overall improvement may be due to better concrete confinement • -Anode resistivity: the most conductive epoxies show low change in Icorr evolution between both measurements. • ->fibresplaynorole in combinationwithveryconductive epoxies • -The CB added epoxies show the worst results. VABOR bijeenkomst - Philippe de Schoesitter

  33. 3. Experiment en toetsing haalbaarheid 3.1 Experiment set-up and program 3.2 Results and discussion 3.3 Conclusion VABOR bijeenkomst - Philippe de Schoesitter

  34. 3.3 Conclusion • CP was effective, CPrev was not obtained • Some improvements for further research: • Integration of reference electrodes • >Suspicion of fibre influence on polarization • >Depolarization measurements • No addition of Chlorides to the mortar and prolonged experiment to investigate Cprev • More specimens (for Tafel experiments and statistical certitude) • Further research on effects of conductive fillers on mechanical behaviour • Further research on integrating this addition in fabrication of prefab laminates VABOR bijeenkomst - Philippe de Schoesitter

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