the physics and chemistry of concrete - :: western ... the virtual... · the virtual cement and...
TRANSCRIPT
![Page 1: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/1.jpg)
The Virtual Cement and Concrete Testing The Virtual Cement and Concrete Testing Laboratory: A modeling example from the Laboratory: A modeling example from the
world of portland cement concreteworld of portland cement concrete
Edward J. GarbocziMaterials and Construction Research Division
Building and Fire Research LaboratoryNational Institute of Standards and Technology
![Page 2: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/2.jpg)
OutlineOutline• Materials background• The VCCTL• Micrometer scale binder – cement paste
– Microstructure formation– Mechanical properties
• Millimeter scale - aggregates– Aggregate shape and structure– Rheology of fresh concrete
• Summary and Prospectus
![Page 3: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/3.jpg)
Concrete
• PCC = your ordinary, everyday, random, complex, multi-scale, time-dependent composite material
• Asphaltic concrete (AC) = similar• Most of PCC research dominated by
empiricism, due to complicated nature of material
• Much of AC research = similar ?
![Page 4: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/4.jpg)
Empiricism to science• Metals, ceramics, and polymers were once thought
to be “messy, craft” materials• Key to transforming the study of metals, ceramics,
and polymers was the availability of enough condensed matter theory (physics and chemistry) being applied to complex microstructures
• Key for random materials like PCC and AC?
Computational materials science based on sound materials science experiments
![Page 5: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/5.jpg)
m
mm μm
nm
The Length Scales of ConcreteThe Length Scales of Concrete
Main NIST materials research
Note: Durability predictionNote: Durability predictionrequires information at all requires information at all length scaleslength scales
Earlystageresearch
Structuralengineering
Å
![Page 6: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/6.jpg)
Focus of NIST research in concreteFocus of NIST research in concrete
• The Virtual Cement and Concrete Testing Laboratory (VCCTL)
• Vision: Just as significant modern structures are not designed without finite element programs, so we desire that significant material design of concrete will not be done without computer-aided assistance like VCCTL
• Durability prediction = our end goal
![Page 7: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/7.jpg)
VCCTL• Internet-based and menu driven• Predicts properties based on detailed microstructure
simulations of well-characterized starting materials• Goal is to reduce number of physical concrete tests,
thus expediting R&D process• Based on NIST modeling effort over last 16 years
– Brings together basic research on processing (cement chemistry), microstructure (multi-scale), and properties (physical and chemical)
• Industrial consortium members: W.R. Grace, SIKA, ATILH, MBT, VDZ, PCA, NSSGA/ICAR, NRMCA
![Page 8: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/8.jpg)
Simulation of a physical Simulation of a physical testing laboratorytesting laboratory
• Cement and aggregate databases– instead of bins and hoppers
• Material combination and concrete curing models– instead of mixers and molds
• Software interface – instead of a cart to take materials and samples
around the laboratory• Accurate models for performance prediction
– instead of instrumented testing machines
![Page 9: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/9.jpg)
Micrometer scale binder Micrometer scale binder -- cement pastecement paste
(1) Microstructure formation
(2) Mechanicalproperties
![Page 10: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/10.jpg)
Tricalcium Silicate (idealized)
DissolutionCa3SiO5 + 3 H2O → 3 Ca2+ + H2SiO4
2- + 4 OH-
Growth of C-S-Hx Ca2+ + H2SiO4
2- + 2(x-1) OH- → CaOx–SiO2–H2O
Growth of PortlanditeCa2+ + 2 OH- → Ca(OH)2
Value of x depends on local pore solution chemistry, reality is much more complicated
Modeling Challenges: Cement ChemistryModeling Challenges: Cement ChemistryModeling Challenges: Cement Chemistry
![Page 11: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/11.jpg)
Modeling Challenges: MicrostructureModeling Challenges: MicrostructureModeling Challenges: Microstructure
MicroMicro--scalescale
75 µm75 µm
Kinetic ImplicationsKinetic Implications•• Nucleation sitesNucleation sites•• CC--SS--H growth = diffusion barrierH growth = diffusion barrier•• Water availabilityWater availability
![Page 12: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/12.jpg)
Ca
Si
K
AlK
… X-ray elementmaps …
… segment image into phases …
SEM/BSE Image…
Measure autocorrelation fns on majority phases
… Particle Size Distribution …
Cement CharacterizationCement Characterization
![Page 13: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/13.jpg)
A model that:• captures chemistry, physics, and microstructure of
hydration• is based on real material thermodynamic and
kinetic parameters• has intrinsic time scaling and correct length scaling• simulates diffusion, dissolution, nucleation, and
growth using only real material parameters• converges to known rate laws for diffusion and
chemical reactions• changes material sets as easily as changing lines in a
database
What do we really want?What do we really want?
![Page 14: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/14.jpg)
CEMHYD3D (NIST) CEMHYD3D (NIST) (works well in many ways)(works well in many ways)
• Digital image basis• Accurate microstructure representationBut:• Rule-based to mimic reaction and diffusion• Little or no kinetic information• Difficult to change materials
Existing Cement Hydration ModelExisting Cement Hydration ModelExisting Cement Hydration Model
![Page 15: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/15.jpg)
• Discretize on regular grid• Stochastic methods for diffusion and reaction• Algorithms are mechanistically based, and
converge to standard PDE rate equations• Applies to general aqueous mineral systems• Micrometer level
• Note: Microstructure and chemistry are being simultaneously simulated
New Model: HydratiCANew Model: HydratiCANew Model: HydratiCA
![Page 16: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/16.jpg)
Mesh Class
Node Classneighbors, volume, materials,methods for transport and rx
Base Material Class
(Liquid, Solid, Gel, Crystal, Solute)
Ion Database Class
ID, mol wt, radius, intrinsic diffusivity, charge(immutable)
Dimensions, resolution, clock, phase stats, thermal condition, moisture conditions, databases
ID, composition, ρ, Ω, Cp, porosity, mobility, virtual methods for material-specific behavior
Derived Material Classes
Methods for material-specific behaviorencoded here
Material Database Class
Reaction Database ClassID, reactants, products, molar stoichiometric coefficients, reaction enthalpy, activation enthalpy, equilibrium constant baseline rate constant
C++, object-oriented modular construction
![Page 17: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/17.jpg)
HydratiCA: Chemical ReactionsHydratiCA: Chemical ReactionsHydratiCA: Chemical Reactions
• Reaction events are localized within a node• List of available reactants is generated and
compared against reaction database• Unit reaction is executed (n cells of A and
m cells of B are removed, p cells of C are added) on a probabilistic basis
• Probability proportional to rate constant k
a A + b B a A + b B →→ c Cc Ck
![Page 18: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/18.jpg)
HydratiCA: Modeling EquilibriumHydratiCA: Modeling EquilibriumHydratiCA: Modeling Equilibrium
a A + b B a A + b B →→ c Cc Ckf
c C c C →→ a A + b Ba A + b Bkr
d{C}dt
= k f {A}a{B}b d{C}dt
= −kr{C}c
At equilibrium:At equilibrium:At equilibrium: kr{C}c = k f {A}a{B}b
k f
kr
={C}c
{A}a{B}b = Keq
![Page 19: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/19.jpg)
HydratiCA: Chemical EquilibriumHydratiCA: Chemical EquilibriumHydratiCA: Chemical Equilibrium
Equilibrium
Precipitation
Dissolution
Ca(OH)2 Ca2+ + 2OH-kf
kr
kf = 2.17x10-7 moles/m2/skr = 3.29x10-3 moles/m2/s
![Page 20: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/20.jpg)
Nucleation from a single seed
Surface nucleation
![Page 21: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/21.jpg)
Elastic properties of allmajor phases known.Typical size is 1003 = 106 elements
Each voxel is a tri-linear finite element
4
Mechanical properties of cement paste binderMechanical properties of cement paste binder
![Page 22: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/22.jpg)
w/c=0.25
28 day microstructures
w/c=0.30 w/c=0.35 w/c=0.40
w/c=0.45 w/c=0.50 w/c=0.55 w/c=0.60
![Page 23: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/23.jpg)
0
5
10
15
20
25
30
35
0.2 0.3 0.4 0.5 0.6 0.7
14 d Holcim (modified)
E(exp)E(mod)G(exp)G(mod)
E,G
(GP
a)
w/c
results
![Page 24: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/24.jpg)
Note: Large FEM simulationsNote: Large FEM simulations
• Using MPI, large FEM simulations are possible on Linux cluster
• Have done linear elastic simulations with over 200,000,000 tri-linear cubic elements
![Page 25: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/25.jpg)
(1)Aggregate shapeand structure
(2) Rheology of fresh concrete
Millimeter scale Millimeter scale -- aggregatesaggregates
Tomograph courtesy of FHWA
![Page 26: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/26.jpg)
Spherical harmonic analysis• Measure r(θ, φ) from center of mass to surface
• Compute anm by inverting r(θ, φ) = Σn,m anm Ynm(θ, φ)
– Ynm = spherical harmonic function
• Random shape will be analytically known – just like simple shapes like spheres and ellipsoids
• All shape and size information for particle is in the (N+1)2
coefficients
![Page 27: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/27.jpg)
How to get 3-D surface points: X-ray computed tomography
X-raysX-rays
Emitter Detector
Picked up from a stream bed on a family hike
![Page 28: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/28.jpg)
n=0
n=30
![Page 29: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/29.jpg)
AMRL fine aggregate for HMA
![Page 30: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/30.jpg)
ASTM C-33 sand
![Page 31: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/31.jpg)
L = 3.85
W = 3.17
T = 1.0
ASTM D 4791L = lengthW = widthT = thickness
![Page 32: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/32.jpg)
W-5 0.0W-4 0.0 0.0W-3 0.3 0.2 0.0W-2 4.5 1.4 0.6 0.0W-1 63.4 27.1 2.2 0.0 0.0
L-1 L-2 L-3 L-4 L-5
ASTM C-33 sand
W-5 0.0W-4 0.0 0.0W-3 0.5 1.3 0.0W-2 8.5 8.9 3.8 0.0W-1 32.4 37.4 6.7 0.4 0.2
L-1 L-2 L-3 L-4 L-5
Sand for hot-mix asphalt
![Page 33: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/33.jpg)
![Page 34: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/34.jpg)
![Page 35: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/35.jpg)
![Page 36: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/36.jpg)
![Page 37: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/37.jpg)
![Page 38: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/38.jpg)
Cement paste
Concrete – truck and rheometer
Mortar
MultiMulti--scale approach to scale approach to experimental rheologyexperimental rheology
![Page 39: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/39.jpg)
Brownian Dynamics + Momentum Conserving CollisionHydrodynamic Behavior
Concrete Rheology Model: Dissipative Particle Dynamics
Model developed by N. Martys (NIST) based on an algorithm by Hoogerbrugge and Koelman (1992)
![Page 40: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/40.jpg)
33--D dissipative particle dynamics simulation D dissipative particle dynamics simulation of realof real--shape aggregates in simple shear flowshape aggregates in simple shear flow
Requires large parallel computers
![Page 41: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/41.jpg)
Mix masters try to crack code for constructionResearchers are borrowing a million hours of processor time from NASA to analyze how concrete is combined—and to find the right recipe for building success
March 24, 2006
![Page 42: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/42.jpg)
SummarySummary
• Transformation of “messy empiricism” to scientific material requires both kinds of basic materials science
– Strong support from industry via VCCTL consortium
– Cement and concrete industry sees this need• Computational materials science is
transforming concrete in the same way as the fields of ceramics, metals, and polymers have already been changed
![Page 43: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/43.jpg)
ProspectusProspectus
• Is a Virtual Asphaltic Concrete Testing Laboratory (VACTL) on the path of progress?
– Characterize asphalt, aggregates (dust to coarse)– Model for chemistry of asphalt matrix, model for
packing of aggregates– Models for response of AC to mechanical and
chemical and thermal loads– Similar in some ways to the project that FHWA
began in the 1990’s, but more chemistry and real particle shapes now possible
![Page 44: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/44.jpg)
Acknowledgements
• NIST – Dale Bentz, Jeff Bullard, Clarissa Ferraris, Nick Martys, Ken Snyder, Paul Stutzman
• Univ. Texas – Sinan Erdogan, David Fowler
• VCCTL – various industrial members• FHWA – Dick Livingston, Habeeb Saleh
![Page 45: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/45.jpg)
Electronic monograph on the computational materials science of concrete
http://ciks.cbt.nist.gov/monograph/
Computation of properties and performance
MODEL
nmnm μμmm mmmmREAL
![Page 46: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/46.jpg)
17th ACBM/NIST Computer Modeling Workshop June 26-29, 2006
![Page 47: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/47.jpg)
HydratiCA: Modeling Aqueous DiffusionHydratiCA: Modeling Aqueous DiffusionHydratiCA: Modeling Aqueous Diffusion
• Based on a random walker algorithm• Each computational node contains a
number of “cells” of solute and water• In any time step, each cell can execute a
single step in a random direction• Probability of stepping is proportional to
the solute mobility and the time increment
p = D Δt/λ2
![Page 48: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/48.jpg)
HydratiCA: Ionic DiffusionHydratiCA: Ionic DiffusionHydratiCA: Ionic Diffusion
• Effective mobility of a charged species is influenced by long-range Coulombicinteractions with other charged species
• Local charge neutrality is required, even though different ions have different mobilities
• HydratiCA can estimate the electrostatic potential at each time step, and include it in the electrochemical potential
• Results in biased random walk
![Page 49: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/49.jpg)
Coupled diffusion of ionsCoupled diffusion of ionsCoupled diffusion of ions
DDCaCa = 0.7 x 10= 0.7 x 10--55 cmcm22/s/s
DDOHOH = 5.3 x 10= 5.3 x 10--55 cmcm22/s/s
![Page 50: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/50.jpg)
x
*
Hr
Hp
ΔH*rev
ΔH*f
HydratiCA: Temperature EffectsHydratiCA: Temperature EffectsHydratiCA: Temperature Effects
![Page 51: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/51.jpg)
Ca(OH)2 Ca2+ + 2OH-
ΔHrxo = -17.88 kJ/mole
kf
kr
lnKeq (T) = lnKeq (298) +
ΔHro
R
HydratiCA: Temperature EffectsHydratiCA: Temperature EffectsHydratiCA: Temperature Effects
1298
−1T
⎡ ⎣ ⎢
⎤ ⎦ ⎥
![Page 52: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/52.jpg)
Need for particle shape analysis in composite materials
• Composites are affected by the shape and property contrast between phases
• Dilute limit shows shape and contrast dependence:P = P1 (1 + [P] c)
• c = volume fraction• P1 is old property• P is new property• [P] is intrinsic property
• If property contrast is small, then [P] does not depend on shape
• If property contrast is high, then [P] depends sensitively on shape
1
2
![Page 53: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/53.jpg)
![Page 54: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/54.jpg)
Relative ViscosityRelative Viscosity
η2 = True or absolute composite plastic viscosityη1 = True or absolute binder plastic viscosity
f(G, C) = function depending on the rheometer geometry (G) including slip effects and experimental conditions (C ).
),(),(
1
2
1
2
CGfCGf
ηη
ηη
=
![Page 55: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/55.jpg)
Article in January/February 2006 issue
![Page 56: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/56.jpg)
![Page 57: The Physics and Chemistry of Concrete - :: Western ... The Virtual... · The Virtual Cement and Concrete Testing ... stoichiometric coefficients, reaction enthalpy, ... The Physics](https://reader033.vdocuments.us/reader033/viewer/2022051508/5a9c82b17f8b9af60a8badfc/html5/thumbnails/57.jpg)
Encouragement from other materials
• Metals before dislocation theory• Polymers before molecular chain theory• Ceramics before Prof. Kingery• Were seen as “messy”• “....guiding theme (of Kingery’s work) was that
ceramics should be seen as a class of materials with common and controllable attributes rather than as the products of isolated and idiosyncratic cultures.” (R.J. Brook, Nature 406, 582 (2000)