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AGGREGATION OF NANOPARTICLES IN 1D

AGGREGATION OF NANOPARTICLES IN 1D. The C-S-H gel. RAQUEL GONZALEZ Low dimensional curse 22 February 2009. OUTLINE. Introduction - The cement based materials. C-S-H gel: - Structural models Colloidal models Aggregation Brownian Cluster Dynamics: Isotropic interactions

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AGGREGATION OF NANOPARTICLES IN 1D

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  1. AGGREGATION OF NANOPARTICLES IN 1D The C-S-H gel. RAQUEL GONZALEZ Low dimensional curse 22 February 2009

  2. OUTLINE • Introduction • - The cement based materials. • C-S-H gel: • - Structural models • Colloidal models • Aggregation • Brownian Cluster Dynamics: • Isotropic interactions • Non-isotropic interactions • Preliminar results • Conclusions and perspectives

  3. INTRODUCTION

  4. NANOPARTICLES Wide range of properties Improving our life

  5. Can it be nano??

  6. CEMENT BASED MATERIALS

  7. C-S-H GEL

  8. STRUCTURAL MODEL Calcium Silicon Oxygen Hydrogen Ca-O layer Silicate chain

  9. COLLOIDAL MODELS JENNINGS MODEL 5 nm sized Rounded particles Single Basic Building Block Basic Building Block HD C-S-H LD C-S-H

  10. JENNINGS MODEL Drawbacks: • Link between structural models and colloidal models • Inner and Outer product TEM images 3D 1D

  11. AGGREGATION

  12. AGGREGATION IN C-S-H GEL Existence of Inner and Outer product Two type of forces: Isotropic: V d W Directional a b Geometrical restrictions!!

  13. BROWNIAN CLUSTER DYNAMICS WITH ISOTROPIC INTERACTIONS

  14. Stochastic processes Brownian Dynamics DESPLACEMENT PROPORTIONAL TO TIME

  15. BROWNIAN CLUSTER DYNAMICS APPROACH V(r) Square well potential a 0 1 r b u Algorithm: • clusters are built by forming randomly rigid bonds between neighboring particles with a probability P = 1-exp(u/kT) • monomers/clusters move with no bond breaking nor overlap • clusters are rebuilt at each time step

  16. β α Ea Enl ∆E=E1-Enl E1 Thermodinamic relation

  17. ISOTROPIC INTERACTIONS: DLCA AND RLCA LIMITS Depending on the probability α that particles form a bond at each collision. DLCA α = 1 RLCA α→ 0 (b) [11]

  18. BROWNIAN CLUSTER DYNAMICS WITH NON ISOTROPIC INTERACTIONS

  19. ANISOTROPIC SYSTEM directional interaction + isotropic interaction rotational +translational diffusion

  20. ANISOTROPIC SYSTEM Ω θ Ω the interaction takes place

  21. PRELIMINAR RESULTS

  22. Isotropic interactions p= 0.37 AMORFUS 3D [9]

  23. Non isotropic interactions: α1=1 β1=0.331 α2=1 β2=0 CRYSTALINE 1D [9]

  24. CONCLUSIONS AND PERSPECTIVES

  25. The method allows passing from a 3D structure to a 1D structure as we can see in the results. • In cementitious materials there are two types of systems, the Inner and the Outer product, which correspond with the aggregation of particles in 1D or 3D. • These preliminary results point out that the Basic Building Blocks are not a unique “black” particle they must be have something inside which makes them different. Some MD calculations point out that for similar morphology there are different structures formed.

  26. CSH aggregation My work

  27. REFERENCES [1] J.H. Liao, K.J. Chen, L.N. Xu, C.W. Ge, J. Wang, L. Huang, N. Gu, Appl. Phys. A, 76 (2003)541. [2] H.F.W. Taylor, “Cement chemistry”, Ed.Thomas Telford, 2nd Edition (1998). [3] E. Bonaccorsi, S. Merlino and H.F.W. Taylor, “The crystal structure of jennite, Ca9Si6O18(OH)6·8H2O”, Cement and Concrete Research, 34 (9) 1481-1488 (2004). [4] E. Bonaccorsi, S. Merlino and A.R. Kampf, “The Crystal Structure of tobermorite 14 Å (plombierite), a C–S–H phase”, Journal of the American Ceramic Society, 88 (3) 505-512 (2005). [5] H.M. Jennings, “A model for the microstructure of calcium silicate hydrate in cement paste”, Cement and Concrete Research, 30 (1) 101-116 (2000). [6] A.J. Allen, R.C. Oberthur, D. Pearson, P.Schofield, C.R. Wilding, Development of the fine porosity and gel structure of hydrating cement systems, Phil mag B 56 (1987) 263-268. [7] H.F. Taylor, proposed structure for calcium silicate hydrate gel, J Am Ceram Soc 69(6) (1986) 464-467. [8] E. Allen, J. Henshaw, P. Smith,” A Review of Particle Agglomeration” , Issue1, (2001) [9] J.C. Gimel “Static and dynamical study of aggregating processes using a novel simulation technique: The Brownian Cluster Dynamics” (2007) [10] J. S Dolado, “A molecular Dynamics study of cementitious calcium silicate hydrate gels” Ceram.Soc. 90, 3938 (2007). [11] D.A. Weitz and J.S. Huang. Self similar structures and the kinetics of aggregation of gold colloids. Kinetic of aggregation and gelation. F.Family and D.P.Landau, Elsevier Science publishers, 19, (1984)

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