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Project # 12 – Multiscale modelling

Project # 12 – Multiscale modelling. Denis D avydov ( PhD student ) Milan Jir ásek (supervisor) Bruno Capra (industrial partner) Henrik Stang (academic partner). Multiscale modelling. July 10th, 1983 Born in Perm city, Russia (USSR)

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Project # 12 – Multiscale modelling

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  1. Project # 12 – Multiscale modelling Denis Davydov (PhD student) Milan Jirásek (supervisor) BrunoCapra (industrial partner) Henrik Stang (academic partner) Nanocem-RTN T0+20 Semi-Annual Meeting 10-2007 Madrid

  2. Multiscale modelling • July 10th, 1983 Born in Perm city, Russia (USSR) • Sept. 1998 – June 2000 Lyceum of Perm State Technical University, Russia. • Sept. 2000 – June 2004 Bachelor degree in Applied Mathematics and Computer Science, Department of Mathematical Modeling of Systems and Processes, Perm State Technical University, Russia. Graduation thesis on “Model for superplasticity”. Distinction: cum laudae. • Sept. 2004 – June 2006 Master degree in Applied Mathematics and Computer Science, Department of Mathematical Modeling of Systems and Processes, Perm State Technical University, Russia. Graduation thesis on “Uniaxial strain stability study problem of the nonlinear viscous material”. Distinction: cum laudae. • Feb. 2007 – presentPhD research at Faculty of Civil Engineering, Czech Technical University, Prague. MC-RTN Project nr 12. “MULTISCALE MODELLING” Nanocem-RTN T0+20 Semi-Annual Meeting 10-2007 Madrid

  3. Multiscale modelling Objectives: • Analysis of the role of loading rate in nanoindentation test, understanding and evaluation of the visco-elastic properties from nanoindentation. • Extension of models for micromechanical properties of cement paste to time-dependent behavior. FEM approach as a homogenization technique at the scale of cement paste. • Extension of multiscale model for concrete to time-dependent behavior. This includes analytical homogenization at the scale of mortar and concrete. • Preliminary study on possible extension to inelastic phenomena such as cracking and plastic deformation. Nanocem-RTN T0+20 Semi-Annual Meeting 10-2007 Madrid

  4. Multiscale modelling • Deliverables: • Procedures for evaluation of nanoindentation tests taking into account the influence of loading rate. • Numerical FEM simulation tool for viscoelastic properties of cement paste. • Multiscale model for viscoelastic properties of mortar and concrete. Extension of the homogenization analytical techniques for the visco-elastic deformation. • Recommendations for further investigation of inelastic properties of cement paste. Nanocem-RTN T0+20 Semi-Annual Meeting 10-2007 Madrid

  5. Multiscale modelling • Accomplishment during the first reporting period is • Literature survey on: • Chemistry, morphology, hydration kinetic • Creep and shrinkage effects • Models of the CSH structure and creep theories • Creep modeling from engineering point of view • Thermo-chemo-mechanical couplings • Homogenization, Eshelbian approach, multiscale models • Analytical solutions for indentation problem and dimensionless analysis Nanocem-RTN T0+20 Semi-Annual Meeting 10-2007 Madrid

  6. Force |E0-Eop|/E0 - error E0 R Difference between E0 and E1 E1 h/R -dimensionless depth Multiscale modelling What is the error of Oliver-Pharr procedure of extracting elastic properties induced by experimental hypothesis of half-space homogeneous media? • P tang Difference between E0 and E1 |E0-E1|/E0 - Nanocem-RTN T0+20 Semi-Annual Meeting 10-2007 Madrid

  7. experiment Penetration depth nanometres Kelvin-Maxwell-Voight visco-elastic model Norton’s visco-plastic model time sec Multiscale modelling • Numerical modelling of the nanoindentation experiment Too deep!!! (1.5micron) homogenized respond of surrounding rather then some phase of interest Nanocem-RTN T0+20 Semi-Annual Meeting 10-2007 Madrid

  8. Multiscale modelling • 1) Perform nanoindentation experiments into specific places of cement paste to better capture intrinsic properties • 2) Use different loading rates to distinguish better between viscous and plastic deformation and have several cycles • Try analytical and numericalfitting nanoindentation curves with visco-elastic creep and visco-plastic Norton model. Compare the results • Estimate a minimum area of the phase needed for reliable results “matrix” approach to the indentation measurements Nanocem-RTN T0+20 Semi-Annual Meeting 10-2007 Madrid

  9. All products (matrix) HD-CSH only (manual) force time Multiscale modelling Indent. Module M=E/(1-nu^2) C3S Alite grain Experimental programs to use: Turned out to be Belite Fit model on one experiment And check on another! Nanocem-RTN T0+20 Semi-Annual Meeting 10-2007 Madrid

  10. NEW IDEAS : Deviatoric creep (same for LD and HD) Self-Consistent Upscaling with Eshelby Solution Like a Granular Media = + LD and HD CSH Porosity (different for LD and HD) Nanocem-RTN T0+20 Semi-Annual Meeting 10-2007 Madrid

  11. NEW IDEAS : Force Indentation experiment: UPSCALING (Self-Consistent Scheme) Deviatoric creep (same for LD and HD) Self-Consistent Upscaling with Eshelby Solution Like a Granular Media = + LD and HD CSH Porosity (different for LD and HD) Nanocem-RTN T0+20 Semi-Annual Meeting 10-2007 Madrid

  12. NEW IDEAS : Force Indentation experiment: Volumetric & deviatoric creep UPSCALING (Self-Consistent Scheme) Deviatoric creep (same for LD and HD) Self-Consistent Upscaling with Eshelby Solution Like a Granular Media = + LD and HD CSH Porosity (different for LD and HD) Nanocem-RTN T0+20 Semi-Annual Meeting 10-2007 Madrid

  13. NEW IDEAS : Force Indentation experiment: Use of elaborated analytical Solution based on one, published by Vandamme to fit Deviatoric creep properties From LD and HD CSH Indentation experiments Volumetric & deviatoric creep UPSCALING (Self-Consistent Scheme) Deviatoric creep (same for LD and HD) Self-Consistent Upscaling with Eshelby Solution Like a Granular Media = + LD and HD CSH Porosity (different for LD and HD) Nanocem-RTN T0+20 Semi-Annual Meeting 10-2007 Madrid

  14. NEW PROBLEMS : machine precision Before: After: Points to indent Real indents (with shift!) Unhydrated grain Hope to have HD CSH here Nanocem-RTN T0+20 Semi-Annual Meeting 10-2007 Madrid

  15. NEW PROBLEMS : hard to identify/indent HD Nanocem-RTN T0+20 Semi-Annual Meeting 10-2007 Madrid

  16. NEW IDEAS (2): Use another indentation machine with higher precision, with AFM, but with bad optics Find “good” grains in advance using BSE/electron microscope. BSE BSE AFM indent AFM gradient map End of HD zone Nanocem-RTN T0+20 Semi-Annual Meeting 10-2007 Madrid grain

  17. Effect of the not straight surface: Force Contact square has changed, So the Oliver-Pharr procedure Will give inappropriate results. Is it possible at all to use that Procedure in such a case??? Nanocem-RTN T0+20 Semi-Annual Meeting 10-2007 Madrid

  18. Recent work: Nanocem-RTN T0+20 Semi-Annual Meeting 10-2007 Madrid

  19. ? Recent work (2): Is it good quality mix/clinker!? Nanocem-RTN T0+20 Semi-Annual Meeting 10-2007 Madrid

  20. Recent work (3): Nanocem-RTN T0+20 Semi-Annual Meeting 10-2007 Madrid

  21. MATRIX vs MANUAL Is it possible at all to access Properties of the phase of Interest by matrix method? Success will probably depend on ratio between characteristic size of the phase and distance between the indents. BUT in order to have indents close to each other one has to do small depths, which, from the morphological point of view for CSH, has to be greater then 100nm Does it worth trying to chose right indents from big matrix? Nanocem-RTN T0+20 Semi-Annual Meeting 10-2007 Madrid

  22. Multiscale modelling • Perspectives: • Have more reliableprocedure for nanoindentation of cement phase (with manual method or with choosing indents from a “matrix” method) • Better understand viscous and plastic behaviour during loading phase of indentation using different indentation rates • Have reliable results for cyclic loading by manual choice of indentation points and maximum penetration depth • Come up with a reliable model to describe the indentation experiment Nanocem-RTN T0+20 Semi-Annual Meeting 10-2007 Madrid

  23. Multiscale modelling • Questions (Chemistry and Sample preparation/mixing): • What is the good C/S ratio for HD/LD CSH? • It is necessary to have a fresh, very well mixed and vibrated cement in quite a big amount (for good mixing) to provide “homogenous” hydrated paste without air bubbles, bunches of agglomerated aggregates. It is very importantfor good polishing. • Presence of Phosphor?? • Lots of Portlondite in paste?? • The best cement for that purpose?? (white/gray/…) • Questions (Mechanical/Mathematical): • HD CSH zone and indents are often situated on the slope. Corrections to Oliver-Pharr? • Statistical lack of experimental curves in manual method to be representative, very time consuming. • Do properties of the CSHchange in time?? What is right age to make indents??? According to some experiments (??) after one year the creep is recoverable absolutely. • Problems with manual indentation, machine precision or HD CSH finding Nanocem-RTN T0+20 Semi-Annual Meeting 10-2007 Madrid

  24. Multiscale modelling • Thank you for you attention! Nanocem-RTN T0+20 Semi-Annual Meeting 10-2007 Madrid

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