Cracking risk in early-age RC wallsMSc. Eng. Agnieszka KNOPPIK-WRÓBELSilesian University of Technology, Gliwice, PolandFac...
Agenda1 Development of cracks in RC wallsThermal–shrinkage crackingFactors of influence2 Numerical modelThermal and moistur...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFa...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFa...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFa...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFa...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFa...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFa...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFa...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFa...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFa...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFa...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFa...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFa...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFa...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFa...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFa...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal and moisture analysi...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal and moisture analysi...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal and moisture analysi...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal and moisture analysi...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal and moisture analysi...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–moisture analysisStr...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–moisture analysisStr...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–moisture analysisStr...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–moisture analysisStr...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–moisture analysisStr...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperat...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperat...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperat...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperat...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperat...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperat...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperat...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperat...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperat...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperat...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperat...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperat...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperat...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsResearch importanceAgnieszka...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsResearch importanceImportanc...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsResearch importanceImportanc...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsResearch importanceImportanc...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsDiscussion of resultsAgniesz...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsDiscussion of resultsTechnol...
Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsDiscussion of resultsTechnol...
9th fib International PhD Symposium in Civil Engineering22–25 July 2012Karlsruhe Institute of Technology, Germany
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fib PhD Symposium 2012 Presentation on "Cracking risk in early-age RC walls"

  1. 1. Cracking risk in early-age RC wallsMSc. Eng. Agnieszka KNOPPIK-WRÓBELSilesian University of Technology, Gliwice, PolandFaculty of Civil EngineeringDepartment of Structural EngineeringKarlsruhe, 22-25 July 2012
  2. 2. Agenda1 Development of cracks in RC wallsThermal–shrinkage crackingFactors of influence2 Numerical modelThermal and moisture analysisThermal–shrinkage strainsStress analysisImplementation3 Analysis of RC wallThermal–moisture analysisStress analysisDamage intensity analysis4 Parametric studyInfluence of ambient temperature and temperature differenceInfluence of time of formwork removalInfluence of concrete mix composition5 Conclusions
  3. 3. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFactors of influenceThermal–moisture effectsFigure 1: Hoover Dam, USAconcretewater + cement + aggregateAgnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  4. 4. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFactors of influenceThermal–moisture effectsFigure 1: Hoover Dam, USAconcretewater + cement + aggregatecement hydrationhighly exothermic processAgnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  5. 5. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFactors of influenceThermal–moisture effectsFigure 1: Hoover Dam, USAconcretewater + cement + aggregatecement hydrationhighly exothermic processheat and moisture transporttemperature and moisture gradientsAgnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  6. 6. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFactors of influenceThermal–moisture effectsFigure 1: Hoover Dam, USAconcretewater + cement + aggregatecement hydrationhighly exothermic processheat and moisture transporttemperature and moisture gradientsstressesthermal–shrinkage stresses in structureAgnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  7. 7. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFactors of influenceInternal restraint vs. external restraintAgnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  8. 8. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFactors of influenceInternal restraint vs. external restraintinternal restraintresult of temperature andmoisture gradients withinthe elementself-induced stressespredominant: massive structuresblock foundationsgravity damsmassive retaining wallsAgnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  9. 9. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFactors of influenceInternal restraint vs. external restraintinternal restraintresult of temperature andmoisture gradients withinthe elementself-induced stressespredominant: massive structuresblock foundationsgravity damsmassive retaining wallsexternal restraintlimitation of deformation bymature concrete of previouslycast layersrestraint stressespredominant: restrained structurestank wallsnuclear containment wallsbridge abutmentsAgnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  10. 10. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFactors of influenceCracking pattern in RC wallsFigure 2: Cracking pattern observed in a real RC wall.Agnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  11. 11. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFactors of influenceCracking pattern in RC wallsh1/3-2/3hhhl21cr2cr lcrwk,maxwk,maxFigure 3: Typical cracking pattern in RC wall.Agnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  12. 12. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFactors of influenceFactors affecting the risk of early-age crackingFactors contributing to the complex process of thermal–shrinkagecracking of RC walls:Agnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  13. 13. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFactors of influenceFactors affecting the risk of early-age crackingFactors contributing to the complex process of thermal–shrinkagecracking of RC walls:1 thermal properties of concrete dependent on concrete mixcompositionAgnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  14. 14. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFactors of influenceFactors affecting the risk of early-age crackingFactors contributing to the complex process of thermal–shrinkagecracking of RC walls:1 thermal properties of concrete dependent on concrete mixcomposition2 conditions during casting and curing of concreteAgnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  15. 15. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFactors of influenceFactors affecting the risk of early-age crackingFactors contributing to the complex process of thermal–shrinkagecracking of RC walls:1 thermal properties of concrete dependent on concrete mixcomposition2 conditions during casting and curing of concrete3 technology of concretingAgnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  16. 16. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFactors of influenceFactors affecting the risk of early-age crackingFactors contributing to the complex process of thermal–shrinkagecracking of RC walls:1 thermal properties of concrete dependent on concrete mixcomposition2 conditions during casting and curing of concrete3 technology of concreting4 environmental conditionsAgnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  17. 17. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–shrinkage crackingFactors of influenceFactors affecting the risk of early-age crackingFactors contributing to the complex process of thermal–shrinkagecracking of RC walls:1 thermal properties of concrete dependent on concrete mixcomposition2 conditions during casting and curing of concrete3 technology of concreting4 environmental conditions5 dimensions and geometry of concrete structureAgnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  18. 18. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal and moisture analysisThermal–shrinkage strainsStress analysisImplementationGeneral assumptions1 phenomenological modelfull coupling of thermal and moisture fieldsdecoupling of thermal–moisture and mechanical fields2 stress state determined under the assumption thatthermal–moisture strains have distort character3 viscoelasto–viscoplastic material model of concreteAgnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  19. 19. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal and moisture analysisThermal–shrinkage strainsStress analysisImplementationThermal and moisture analysisCoupled thermal–moisture equations˙T = div(αTT gradT + αTW gradc) +1cbρqv˙c = div(αWW gradc + αWT gradT) − KqvInitial conditionsT(xi , t = 0) = Tp(xi , 0)c(xi , t = 0) = cp(xi , 0)Boundary conditionsnT(αTT gradT + αTW gradc) + ˜q = 0nT(αWW gradc + αWT gradT) + ˜η = 0Agnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  20. 20. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal and moisture analysisThermal–shrinkage strainsStress analysisImplementationThermal–shrinkage strainsImposed thermal–shrinkage strains εεεn:volumetric strainsdεεεn= dεnx dεny dεnz 0 0 0calculated based on predetermined temperature and humiditydεnx = dεny = dεnz = αT dT + αW dWW = f (c)Agnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  21. 21. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal and moisture analysisThermal–shrinkage strainsStress analysisImplementationStress analysisviscoelastic area˙σσσ = Dve(˙εεε − ˙εεεn− ˙εεεc)viscoelasto–viscoplastic area˙σσσ = Dve(˙εεε − ˙εεεn− ˙εεεc− ˙εεεvp)failure surfacestress pathoctoctoctfmFigure 4: Damage intensity factor.possibility of crack occurrencesl =τoctτfoctFigure 5: Failure surface development.Agnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  22. 22. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal and moisture analysisThermal–shrinkage strainsStress analysisImplementationImplementationpre-processor & post-processordata preparation & presentationwith ParaViewprocessorTEMWILthermal–moisture fieldsMAFEM_YOUNGstress analysisAgnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  23. 23. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–moisture analysisStress analysisDamage intensity analysisBasic caseconcrete class C30/37, steel class RB400cement type CEM I 42.5R, 375 kg/m3,ambient temperature Tz = 25◦C, initial temperature of concrete Tp = 25◦C,wooden formwork of 1.8 cm plywood removed after 28 days,no insulation, protection of top surface with foil.20.0 m0.7m4.0m4.0 m0.7 mZYXFigure 6: Geometry and finite element mesh of analysed wall.Agnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  24. 24. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–moisture analysisStress analysisDamage intensity analysisThermal fields40455055ature [°C]interiorsurface202530350 2 4 6 8 10 12 14 16 18 20temperatime [days]Figure 7: Temperature development in time.Agnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  25. 25. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–moisture analysisStress analysisDamage intensity analysisMoisture fields15161718ontent (x100) 3/m3]interiorsurface1213140 2 4 6 8 10 12 14 16 18 20moisture co[m3time [days]Figure 8: Moisture content development in time.Agnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  26. 26. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–moisture analysisStress analysisDamage intensity analysisStress development & deformations0.61.21.8MPa]interiorsurface‐1.8‐1.2‐0.60.00 2 4 6 8 10 12 14 16 18 20stress [Mtime [days]Figure 9: Stress development in time.Agnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  27. 27. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsThermal–moisture analysisStress analysisDamage intensity analysisStress distribution & damage intensity-0,7-0,20,30,81,31,82,32,83,33,8-2,5 -1,5 -0,5 0,5 1,5 2,5height[m]stress [MPa]interiorsurfaceFigure 10: Distribution of stress at the height of the wall.Agnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  28. 28. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperature and temperature differenceInfluence of time of formwork removalInfluence of concrete mix compositionChosen factorsInfluence of the following parameters analysed:Agnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  29. 29. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperature and temperature differenceInfluence of time of formwork removalInfluence of concrete mix compositionChosen factorsInfluence of the following parameters analysed:1 ambient temperature and temperature differenceTz = Tp = 25◦C (basic), 20◦C or 15◦Cpre-cooling by 5◦C or 10◦CAgnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  30. 30. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperature and temperature differenceInfluence of time of formwork removalInfluence of concrete mix compositionChosen factorsInfluence of the following parameters analysed:1 ambient temperature and temperature differenceTz = Tp = 25◦C (basic), 20◦C or 15◦Cpre-cooling by 5◦C or 10◦C2 time of formwork removalafter 28 days (basic)after 3 daysAgnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  31. 31. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperature and temperature differenceInfluence of time of formwork removalInfluence of concrete mix compositionChosen factorsInfluence of the following parameters analysed:1 ambient temperature and temperature differenceTz = Tp = 25◦C (basic), 20◦C or 15◦Cpre-cooling by 5◦C or 10◦C2 time of formwork removalafter 28 days (basic)after 3 days3 concrete mix composition (type and amount of cement)CEM I 42.5R 375 kg (basic), 325 kg or 425 kgCEM II B-S 42.5N, CEM III/A 42.5N or CEM V/A 32.5RAgnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  32. 32. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperature and temperature differenceInfluence of time of formwork removalInfluence of concrete mix compositionDamage intensity maps (after 20 days) comparison(a)Tz =Tp=15◦C (b)Tz =Tp=20◦C (c)Tz =Tp=25◦CFigure 11: Damage intensity maps in the interior of the wall (ambient temperature).Agnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  33. 33. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperature and temperature differenceInfluence of time of formwork removalInfluence of concrete mix compositionDamage intensity maps (after 20 days) comparison(a)Tz =Tp=15◦C (b)Tz =Tp=20◦C (c)Tz =Tp=25◦CFigure 11: Damage intensity maps in the interior of the wall (ambient temperature).(a)Tz =25◦C, Tp=25◦C (b)Tz =25◦C, Tp=20◦C (c)Tz =25◦C, Tp=15◦CFigure 12: Damage intensity maps in the interior of the wall (temp. difference).Agnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  34. 34. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperature and temperature differenceInfluence of time of formwork removalInfluence of concrete mix compositionMaximum damage intensity factor comparison0.530 370.540 390.570 390.45 0.45 0.470.50.60.70.80.91.0tensity factorinteriorsurface0.370.230.390.250.390.260.320.220.340.230.340.230.00.10.20.30.4damage intFigure 13: Influence of ambient temperature and temperature difference on damageintensity factor.Agnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  35. 35. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperature and temperature differenceInfluence of time of formwork removalInfluence of concrete mix compositionDamage intensity maps (after 20 days) comparison(a)Tz =Tp=25◦C, 28 days (b)Tz =Tp=25◦C, 3 daysFigure 14: Damage intensity maps in the interior of the wall.Agnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  36. 36. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperature and temperature differenceInfluence of time of formwork removalInfluence of concrete mix compositionDamage intensity maps (after 20 days) comparison(a)Tz =Tp=25◦C, 28 days (b)Tz =Tp=25◦C, 3 daysFigure 14: Damage intensity maps in the interior of the wall.(a)Tz =Tp=25◦C, 28 days (b)Tz =Tp=25◦C, 3 daysFigure 15: Damage intensity maps on the surface of the wall.Agnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  37. 37. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperature and temperature differenceInfluence of time of formwork removalInfluence of concrete mix compositionMaximum damage intensity factor comparison0.53 0.56 0.54 0.57 0.57 0.590.450.790.450.790.470.810.50.60.70.80.91.0tensity factorinteriorsurface0.00.10.20.30.4damage inFigure 16: Influence of time of formwork removal on damage intensity factor.Agnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  38. 38. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperature and temperature differenceInfluence of time of formwork removalInfluence of concrete mix compositionHydration heat of cements200250300350ration, [J/g]0501001500 10 20 30 40 50 60 70 80heat of hydrtime, [h]CEM I 42,5RCEM II/B‐S 42,5NCEM III/A 42,5NCEM V/A (S‐V) 32,5RFigure 17: Development of hydration heat of different types of cements.Agnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  39. 39. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperature and temperature differenceInfluence of time of formwork removalInfluence of concrete mix compositionDamage intensity maps (after 20 days) comparison(a)CEM I 325kg/m3(b)CEM I 375kg/m3(c)CEM I 425kg/m3(d)CEM II 375kg/m3(e)CEM III 375kg/m3(f)CEM V 375kg/m3Figure 18: Damage intensity maps in the interior of the wall.Agnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  40. 40. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsInfluence of ambient temperature and temperature differenceInfluence of time of formwork removalInfluence of concrete mix compositionMaximum damage intensity factor comparison0.490.570.640.530.570.490.470.520 44 0.470 50.60.70.80.91.0ensity factorinteriorsurface0.400.440.410.00.10.20.30.40.5CEM I 42.5R 325kg/m3CEM I 42.5R 375kg/m3CEM I 42.5R 425kg/m3CEM II B‐S 42.5N  375kg/m3CEM III/A 42.5N  375kg/m3CEM V/A 32.5R  375kg/m3damage inteFigure 19: Influence of concrete mix composition on damage intensity factor.Agnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  41. 41. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsResearch importanceAgnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  42. 42. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsResearch importanceImportanceneed to ensure desired service life and function of thestructureon-going examination of early-age cracking problemAgnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  43. 43. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsResearch importanceImportanceneed to ensure desired service life and function of thestructureon-going examination of early-age cracking problemNumerical modelqualitatively and quantitatively proper resultsconformation with present knowledge and experienceAgnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  44. 44. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsResearch importanceImportanceneed to ensure desired service life and function of thestructureon-going examination of early-age cracking problemNumerical modelqualitatively and quantitatively proper resultsconformation with present knowledge and experienceContributionmulti-parameter numerical model of thermal–moisture effects inearly-age concrete and its implementationAgnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  45. 45. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsDiscussion of resultsAgnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  46. 46. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsDiscussion of resultsTechnology and curing conditionsmoderate ambient temperaturespositive influence of initial coolingsurface cracking risk if formwork removed earlyAgnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  47. 47. Development of cracks in RC wallsNumerical modelAnalysis of RC wallParametric studyConclusionsDiscussion of resultsTechnology and curing conditionsmoderate ambient temperaturespositive influence of initial coolingsurface cracking risk if formwork removed earlyConcrete mix compositionlow-heat cements: lower hydration temperatures vs. lowerrate of strength developmentAgnieszka Knoppik-Wróbel Cracking risk in early-age RC walls
  48. 48. 9th fib International PhD Symposium in Civil Engineering22–25 July 2012Karlsruhe Institute of Technology, Germany
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