AGGREGATION OF NANOPARTICLES IN 1D
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AGGREGATION OF NANOPARTICLES IN 1D The C-S-H gel. RAQUEL GONZALEZ Low dimensional curse 22 February 2009
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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 - PowerPoint PPT Presentation
Transcript of AGGREGATION OF NANOPARTICLES IN 1D
AGGREGATION OF NANOPARTICLES IN 1D
The C-S-H gel.
RAQUEL GONZALEZLow dimensional curse22 February 2009
• 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
OUTLINE
INTRODUCTION
Wide range of properties
Improving our life
NANOPARTICLES
Can it be nano??
CEMENT BASED MATERIALS
C-S-H GEL
STRUCTURAL MODEL
Calcium Silicon Oxygen Hydrogen
Silicate chain
Ca-O layer
5 nm sized Rounded particles
SingleBasic Building Block
COLLOIDAL MODELS
LD C-S-H
HD C-S-H
Basic Building Block
JENNINGS MODEL
JENNINGS MODEL
Drawbacks:
• Link between structural models and colloidal models
OP
I P I P
OP OP
I P I P
OP
• Inner and Outer product
3D 1DTEM images
Existence of Inner and Outer product
Two type of forces:
Isotropic: V d W Directional
AGGREGATION IN C-S-H GEL
a
b
Geometrical restrictions!!
BROWNIAN CLUSTER DYNAMICS WITH
ISOTROPIC INTERACTIONS
Stochastic processes Brownian Dynamics
2( ) (0) 6R t R Dtr t
DESPLACEMENT PROPORTIONAL TO TIME
BROWNIAN CLUSTER DYNAMICS APPROACH
• 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
Algorithm:
V(r)
Square well potential
r0
1
u
a
b
Thermodinamic relation
E1
Enl
Ea
∆E=E1-Enl
α
β
exp
Ea Enl
Kb T
1exp
Ea E
Kb T
1
1 expp
EKb T
ln 1u Kb T p
ISOTROPIC INTERACTIONS: DLCA AND RLCA LIMITS
Depending on the probability α that particles form a bond at each collision.
α = 1 α → 0DLCA RLCA
(b)
[11]
BROWNIAN CLUSTER DYNAMICS WITH NON
ISOTROPIC INTERACTIONS
ANISOTROPIC SYSTEM
2
2 2
0 6
0 2 1 exp 2
Trans
Rot
R t R D t
u t u u D t
u
R
directional interaction + isotropic interaction
rotational +translational diffusion
ANISOTROPIC SYSTEM
θ
2 21 2 cosû û
2
1 ´2ˆ ˆarccos u u
the interaction takes place
Ω
Ω
PRELIMINAR RESULTS
Isotropic interactions
p= 0.37
AMORFUS3D
[9]
Non isotropic interactions:α1=1 β1=0.331
α2=1 β2=0
CRYSTALINE1D
[9]
CONCLUSIONS AND PERSPECTIVES
•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.
CSH aggregation
My work
[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)
REFERENCES
