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TRB Webinar:
Overview of Nanotechnology
and Use of Nanomaterials as
Modifiers for Asphalt Binders September 7, 2012
Ellie H. Fini, Ph.D, P.E.
Assistant Prof. at North Carolina A&T State University
Research Scholar at Massachusetts Institute of Technology
Research Emphasis: Alternative Asphalt Binder from Animal Waste
Email: [email protected]
Phone: 336-334-7737 Ex. 665
Modified Asphalt from Particle Stabilized Emulsions
Alan James and Peter Zhou AkzoNobel Surface Chemistry LLC
NANOCOMPOSITES: CLAYS IN POLYMERS
• Dispersions of organically modified clays (“organoclays”) in polymers • Lower moisture and oxygen permeability • Higher impact strength • Less tacky surface • Higher tensile strength
Hummer cargo bed lined with PP- organoclay nanocomposite
NANOCOMPOSITES: CLAYS IN ASPHALT
• Process involves dispersion of organoclay in molten polymer or hot asphalt
• Demonstrated effects on asphalt stiffness and short term ageing.
• ref “Nanotechnology for Binders of Asphalt Mixtures”, Eurobitume 2008, Jeroem Besamusca et al, (Delft University) and others
• Other nano-sized particles also studied in hot asphalt
+
Clay Aggregates Asphalt/Polymer
Nanocomposites
NANOCOMPOSITES VIA EMULSION
+
Organoclay Aggregates
Asphalt
Nanocomposite
High Shear
+
Clay Slurry Asphalt
High Shear
Emulsion
Nanocomposite
Dry
Cold Process Hot Process
NANOCOMPOSITES VIA EMULSION
+
Clay Slurry Asphalt
High Shear
Emulsion
Nanocomposite
Dry
Cold Process
• Clay stabilized emulsion is known technology in non- paving applications
• Cured emulsion to clay modified asphalt in cold process
• Similar process has been demonstrated for polymer latex – clay polymer composites
• Can we exploit the advantages of clay stabilised/clay modified emulsion also in paving applications.
•Can we apply to the other particle stabilized emulsions
MINERAL PARTICLES FOR ASPHALT MODIFICATION
• Bentonite ← • sodium montmorillonite, smectite • sodium aluminum magnesium silicates • layered structure with high cation exchange capacity • Platelets 1 micron diameter x 1 nanometer thick
• Wollastonite • Calcium silicate needles 2-10micron long
• Attapulgite ← • Magnesium aluminum silicate needles 1x 0.01 micron
• Sepiolite • Magnesium silicate fibers 2-10micron
• Nano Silica Bindzil® (Akzo Nobel) ← • 5-20nm spheres • Hydrophobically modified
TYPES OF ASPHALT EMULSION • Chemically Stabilized Emulsions
• Conventional O/W emulsions used in paving operations like CRS-2, SS-1H grades • Stabilized by surfactant emulsifier which provides positive or negative charge to the emulsions droplets • 50-70% residue
• Mineral Stabilized Emulsions • Stabilized with mineral particles • May contain chemical additives. • Typically 40-50% residue (including mineral)
• Mineral Modified Emulsions • Stabilized with chemical emulsifiers • Mineral may be included in the soap, or post added. • Mineral provides stability, modifies residue. • 40-70% residue (including mineral)
MINERAL STABILIZED EMULSIONS
• PG 64 or PG 58 asphalt cement (140°C) added to hot mineral slurry (50°C). • Mixed 2 minutes at 4000-5000rpm in Silverson mixer with a disintegrator head or with Cowles Mixer • Or through conventional colloid mill (Denimotech SEP 0.3)
Laboratory Preparation
In emulsions prepared with bentonite clay droplets are ovoid shape In chemical emulsions and emulsions prepared with Binzil silica, droplets are spherical In clay modified chemical emulsion the droplets are spherical Droplets are 1-40 micron in diameter/length There is a distribution of particle sizes
100 micron/0.1mm
MINERAL STABILIZED EMULSIONS
Chemical stabilized emulsion
Bentonite clay stabilized emulsion
EMULSION PARTICLE SIZE
100 micron/0.1mm 100 micron/0.1mm
0
20
40
60
80
100
120
140
0 3 6 9 12 15 Mineral solids (%) basis residue
Med
ian
parti
cle
size
mic
ron
Colloid Mill
High Speed Mixer
Clay stabilized 2% diamine Chemically stabilized
Particle size depends on the temperature, pH, emulsification conditions, mineral content and chemical content.
Clay Stabilized Emulsion 30% residue
Chemically Stabilized Emulsion 60% residue
MINERAL STABILIZED EMULSIONS
Clay stabilized emulsions are viscous, thixotropic Emulsions prepared with Binzil silica were low viscosity
MINERAL MODIFIED EMULSIONS
100 micron/0.1mm 100 micron/0.1mm
• Difficult to make emulsions with low mineral content by the direct method • Only Bindzil emulsions were stable at low mineral dosages. • To examine the effect of low levels of mineral on the emulsion residue, clay modified emulsions were prepared
• Prepare special chemically stabilized SS-1H emulsion with colloid mill • Add clay or clay slurry to the finished emulsion • Or make special chemical stabilized emulsion but include clay in the soap solution
VISCOSITY OF 50% RESIDUE MODIFIED EMULSION
100 micron/0.1mm
0.5 1.0 1.5 2.0
15
25
20
30
0 10
2.5 %
Visc
osity
SS
F
% bentonite basis residue • Modified emulsions are similar in viscosity to chemically stabilized emulsions and much less viscous than mineral stabilized emulsions. • The mineral content is much lower • The emulsions pass the cement mix test and can be classed “Slow-Setting”
RECOVERY OF EMULSION RESIDUES
100 micron/0.1mm 100 micron/0.1mm
• The emulsion is allowed to evaporate on a silicone sheet at room temperature then at 60C fro 24h.(ASTM D7497) •. The process leads to some hardening of the residue compared to the original binder before emulsification, more than for conventional distillation • A chemical stabilized emulsion residue obtained in this manner graded PG 64-24 (no RTFOT) • The data presented were for emulsions prepared using PG58-28 binder. The residues from PG64 binder showed similar changes.
SOFTENING POINT VS. MINERAL CONTENT
100 micron/0.1mm 100 micron/0.1mm
40
50
60
70
80
0 2 4 6 Mineral w/w% residue
Sof
teni
ng P
oint
°C
90
8 10 12
Bentonite stabilized Bentonite modified
Silica stabilized Attapulgite stabilized
PENETRATION VS. MINERAL CONTENT
100 micron/0.1mm 100 micron/0.1mm
20
40
60
80
100
Mineral w/w% residue
Pen
etra
tion
25°C
dm
m/5
s
0 5 10 15 20 25 30
Bentonite stabilized Bentonite modified
Silica stabilized Attapulgite stabilized
PG GRADE VS. MINERAL CONTENT Low temperature recovery, no RTFOT
100 micron/0.1mm 100 micron/0.1mm
-30
-20
60
70
80
0 2 4 6 Clay w/w% residue
PG
gra
de (n
o R
TFO
T)
100
8 10 12
Clay stabilized Clay modified
Upper grade
Lower grade
USE OF MINERAL STABILISED EMULSION - FOG SEAL
100 micron/0.1mm 100 micron/0.1mm
ADHESION OF MINERAL MODIFIED EMULSIONS Cationic surfactant in binder
No additive Cationic surfactant in binder
• Silica sand coated with emulsion, allowed to cure at room temperature • Subjected to 10minutes boiling stripping test • Coating is good.- comparable to conventional cationic emulsion.
SUMMARY
• Clays and other minerals can be included in bitumen emulsions at levels up to 20% of the residue by weight
• At high levels the emulsion properties are greatly modified with high viscosity, at low levels (<2.5%) the effects on the emulsion viscosity are small
• Generally “slow-setting” emulsions are produced.
• The residue properties are modified – higher softening points and lower penetrations, in proportion to the amount of mineral present.
•The modified emulsions may find use in preventive maintenance and paving applications.
Alan James AkzoNobel Surface Chemistry LLC
525 West Van Buren Street Chicago IL 60607-3835
Desk: 312 544 7455 Cell: 914 525 5307
E-mail [email protected]
Nanomaterials Modified Asphalt and Asphalt Mixtures
Zhanping You, P.E., Ph.D. Associate Professor, Transportation Engineering and Materials Department of Civil and Environmental Engineering Michigan Technological University [email protected] http://www.cee.mtu.edu/ Phone: 906-487-1059
1
Objectives
• Understand how the nanomaterials modified asphalt binder perform
• Study how the asphalt mixtures perform when nano modified asphalt binder is used
2
Materials Preparation • Nano Materials:
Non-modified nanoclay (NMN) Polymer-modified nanoclay (PMN) Nanomer (NI44P) Nanosilica (NS) Carbon microfiber (MCF)- not nano materials
• The nanomaterials modified asphalt binder • The mixtures from the nanomaterials modified
asphalt binder and aggregates
3
Microstructure of Nano- Modified Asphalt
PMN modified asphalt binder Polymer-modified nanoclay
4
Nanosilica modified asphalt binder Nanosilica
Microstructure of Nano- Modified Asphalt
5
Viscosity Test of Asphalt Binders
6
Viscosity: NMN and PMN modified asphalt binders
5.0E+01
5.0E+02
5.0E+03
5.0E+04
100 125 135 150 175 190
Visc
osity
val
ues
(cP)
Temperature (oC)
2% NMN 4% NMN 2% PMN 4% PMN Control
7
5.0E+01
5.0E+02
5.0E+03
5.0E+04
100 125 135 150 175 190
Visc
osity
val
ues
(cP)
Temperature (°C)
2% MCF 4% MCF
2% NI.44p 4% NI.44p
Control
Viscosity: MCF and NI44P modified asphalt binders
8
5.00E+01
5.00E+02
5.00E+03
100 125 135 150 175 190
Visc
osity
val
ues
(cP)
Temperature (oC)
4% Nano Silica 6% Nanosilica Control asphalt
Viscosity: NS modified asphalt binders
9
• The addition of NMN, MCF and NI44P into the control asphalt binder increases the viscosity of the modified asphalt binders.
• However, the addition of PMN and NS into the control asphalt binder decreases the viscosity of the modified asphalt binders.
Viscosity results summary
10
DSR Test of Asphalt Binders
11
DSR: NMN modified asphalt binder
1.0E+00
1.0E+01
1.0E+02
1.0E+03
1.0E+04
1.0E+05
1.0E-04 1.0E-03 1.0E-02 1.0E-01 1.0E+00 1.0E+01 1.0E+02
Com
plex
Mod
ulus
G* (
Pa)
Reduced Frequency (Hz)
2% NMN NMA Fitted G* 2% NMN NMA Measurement G* 4% NMN NMA Fitted G* 4% NMN NMA Measurement G* Control asphalt Fitted G* Control asphalt Measurement G*
12
1.0E+00
1.0E+01
1.0E+02
1.0E+03
1.0E+04
1.0E+05
1.0E-04 1.0E-03 1.0E-02 1.0E-01 1.0E+00 1.0E+01 1.0E+02
Com
plex
Mod
ulus
G* (
Pa)
Reduced Frequency (Hz)
2% PMN NMA Fitted G* 2% PMN NMA Measurement G* 4% PMN NMA Fitted G* 4% PMN NMA Measurement G* Control asphalt Fitted G* Control asphalt Measurement G*
DSR: PMN modified asphalt binder
13
1.0E+00
1.0E+01
1.0E+02
1.0E+03
1.0E+04
1.0E+05
1.0E-04 1.0E-03 1.0E-02 1.0E-01 1.0E+00 1.0E+01 1.0E+02
Com
plex
Mod
ulus
G* (
Pa)
Reduced Frequency (Hz)
4% NS NMA fitted G* 4% NS NMA Measurement G* 6% NS NMA fitted G* 6% NS NMA Measurement G* Control asphalt fitted G* Control asphalt Measurement G*
DSR: NS modified asphalt binder
14
• The complex shear modulus of NMN, MCF and NI44P modified asphalt binders are higher than that of control asphalt binder,
• The complex shear modulus of PMN and NS modified asphalt binders are lower than that of control asphalt binder.
DSR Test Results: Summary
15
1.0E+00
1.0E+01
1.0E+02
1.0E+03
0 50 100 150 200 250 300
Cre
ep S
tiffn
ess
(MPa
)
Loading Time (s)
2% NI.44P NMA Stiffness 4% NI.44P NMA Stiffness 2% MCF modified asphalt Stiffness 4% MCF modified asphalt Stiffness Control Asphalt Stiffness
BBR: NI44P and MCF modified asphalt binders
16
• The modified asphalt binders are all stiffer. The control asphalt binder has the lowest stiffness.
• However, the low-temperature PG grades of control and the modified asphalt binders are the same for the % of nano materials added.
BBR Test Results
17
Fourier Transform Infrared Spectroscopy (FTIR): Control Binder
50010001500200025003000350040000
0.5
1.0
1.5
2.0
2.5
Wavenumber(cm-1)
Abs
orba
nce(
a.u.
)
Control asphalt
UnagedRTFO-agedPAV-aged
RTFO-aged
Unaged
PAV-aged
Unaged Samples
CH=CH S=O C=O C=C C-H of – (CH2)n- C-H of CH3
966 cm-1 1030 cm-1 1690cm-1 1600cm-1 1460cm-1 1376cm-1
18
50010001500200025003000350040000
0.5
1.0
1.5
2.0
2.5
Wavenumber(cm-1)
Abs
orba
nce(
a.u.
)
2% NMN modified asphalt
UnagedRTFO-agedPAV-aged
RTFO-aged
UnagedPAV-aged
50010001500200025003000350040000
0.5
1.0
1.5
2.0
2.5
Wavenumber(cm-1)A
bsor
banc
e(a.
u.)
4% NMN modified asphalt
UnagedRTFO-agedPAV-aged
RTFO-aged
PAV-aged
Unaged
FTIR: NMN Modified Asphalt Binder
Unaged Samples
CH=CH S=O C=O C=C C-H of – (CH2)n- C-H of CH3
966 cm-1 1030 cm-1 1690cm-1 1600cm-1 1460cm-1 1376cm-1
19
• In general, the line trend of FTIR in the control asphalt is different from the trends of modified asphalt binders. It represents that there may have been chemical reactions between the nano modifiers and control asphalt binder.
• The new microstructures were formed in the modified asphalt binder.
FTIR Test Results:
20
Dynamic Modulus Test of Asphalt Mixtures
21
1.0E+00
1.0E+01
1.0E+02
1.0E+03
1.0E+04
1.0E+05
1.0E-08 1.0E-06 1.0E-04 1.0E-02 1.0E+00 1.0E+02
E* (M
Pa)
Reduced Frequency (Hz)
Fitted E* (2%NMN modified asphalt mixture) Laboratory E* (2%NMN modified asphalt mixture) Fitted E* (4%NMN modified asphalt mixture) Laboratory E* (4%NMN modified asphalt mixture) Fitted E* (Control asphalt mixture) Laboratory E* (Control asphalt mixture)
High temperatures and low frequencies
Low temperatures and high frequencies
Dynamic Modulus: NMN Modified Asphalt Mixture
22
1.0E+00
1.0E+01
1.0E+02
1.0E+03
1.0E+04
1.0E+05
1.0E-08 1.0E-06 1.0E-04 1.0E-02 1.0E+00 1.0E+02
E* (M
Pa)
Reduced Frequency (Hz)
Fitted E* (2%PMN modified asphalt mixture) Laboratory E* (2%PMN modified asphalt mixture) Fitted E* (4%PMN modified asphalt mixture) Laboratory E* (4%PMN modified asphalt mixture) Fitted E* (Control asphalt mixture) Laboratory E* (Control asphalt mixture)
Low temperatures and high frequencies
Dynamic Modulus: PMN Modified Asphalt Mixture
23
1.0E+00
1.0E+01
1.0E+02
1.0E+03
1.0E+04
1.0E+05
1.0E-07 1.0E-05 1.0E-03 1.0E-01 1.0E+01
E* (M
Pa)
Reduced Frequency (Hz)
Fitted E* (2%MCF modified asphalt mixture) Laboratory E* (2%MCF modified asphalt mixture) Fitted E* (4%MCF modified asphalt mixture) Laboratory E* (4%MCF modified asphalt mixture) Fitted E* (Control asphalt mixture) Laboratory E* (Control asphalt mixture)
Dynamic modulus: MCF Modified Asphalt Mixture
24
1.0E+00
1.0E+01
1.0E+02
1.0E+03
1.0E+04
1.0E+05
1.0E-08 1.0E-06 1.0E-04 1.0E-02 1.0E+00 1.0E+02
E* (M
Pa)
Reduced Frequency (Hz)
Fitted E* (2%NI44P modified asphalt mixture) Laboratory E* (2%NI44P modified asphalt mixture) Fitted E* (4%NI44P modified asphalt mixture) Laboratory E* (4%NI44P modified asphalt mixture) Fitted E* (Control asphalt mixture) Laboratory E* (Control asphalt mixture)
Dynamic Modulus: NI44P Modified Asphalt Mixture
25
Dynamic Modulus: NS Modified Asphalt Mixture
1.0E+00
1.0E+01
1.0E+02
1.0E+03
1.0E+04
1.0E+05
1.0E-08 1.0E-06 1.0E-04 1.0E-02 1.0E+00 1.0E+02
E* (M
Pa)
Reduced Frequency (Hz)
Fitted E* (4%NS modified asphalt mixture) Laboratory E* (4%NS modified asphalt mixture) Fitted E* (6%NS modified asphalt mixture) Laboratory E* (6%NS modified asphalt mixture) Fitted E* (Control asphalt mixture) Laboratory E* (Control asphalt mixture)
26
• The addition of micro- and nano- materials into the control asphalt mixture, the dynamic modulus of the modified asphalt mixtures improves.
Dynamic Modulus Test Results: Summary
27
APA Rutting Test: Asphalt Mixtures
28
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
0 1000 2000 3000 4000 5000 6000 7000 8000
Perm
anen
t Def
orm
atio
n (m
m)
Loading Cycles
Control asphalt mixture
2% NMN modified asphalt mixture
4% NMN modified asphalt mixture
APA Rutting: NMN Modified Asphalt Mixture
29
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
0 1000 2000 3000 4000 5000 6000 7000 8000
Perm
anen
t Def
orm
atio
n (m
m)
Loading Cycles
Control asphalt mixture
2% PMN modified asphalt mixture
4% PMN modified asphalt mixture
APA Rutting: PMN Modified Asphalt Mixture
30
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
0 1000 2000 3000 4000 5000 6000 7000 8000
Perm
anen
t Def
orm
atio
n (m
m)
Loading Cycles
Control asphalt mixture
2% MCF modified asphalt mixture
4% MCF modified asphalt mixture
APA Rutting: MCF Modified Asphalt Mixture
31
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
0 1000 2000 3000 4000 5000 6000 7000 8000
Perm
anen
t Def
orm
atio
n (m
m)
Loading Cycles
control asphalt mixture
2% NI44P modified asphalt mixture
4% NI44P modified asphalt mixture
APA Rutting: NI44P Modified Asphalt Mixture
32
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
0 1000 2000 3000 4000 5000 6000 7000 8000
Perm
anen
t Def
orm
atio
n (m
m)
Loading Cycles
Control asphalt mixture
4% NS modified asphalt mixture
6% NS modified asphalt mixture
APA rutting: NS Modified Asphalt Mixture
33
• The rut depths of micro- and nano- materials modified asphalt mixtures decrease relative to the control asphalt mixture.
• Smaller rutting amount for greater percentage of micro- and nano- materials in mixtures.
APA Rutting Test Results
34
Conclusions • Based on the viscosity and DSR data, the addition of
materials (NMN, MCF, NI44P) into control asphalt binder improve the viscosity and complex shear modulus of modified asphalt binders.
• However, the addition of PMN and NS would decrease the viscosity and complex shear modulus of modified asphalt binders compared to the control asphalt binder.
35
• The addition nano-materials ay degrade the low-temperature performance of modified asphalt binder from the BBR test data, but the PG grade remains the same. More work is ongoing to improve the low-temperature performance.
• The dynamic modulus and rutting resistance performance improve relative to the control asphalt mixtures.
Conclusions
36
• This presentation is for information change only. • The study is still in its very early stage. • The presentation is very brief due to time restrictions.
More information on the topic can be seen in related published and unpublished articles.
• The work cannot be done without the contribution of Julian Mills-Beale and Hui Yao of Michigan Tech, and many collaborators in Michigan Tech and other institutions.
Other Notes
37
Cementitious Materials Genome, Nanostructures and Modeling
Ram Mohan, Ph.D. Department of Nanoengineering
Joint School of Nanoscience and Nanoengineering North Carolina A&T State University
Greensboro, NC 27401
TRB Webinar Overview of Nanotechnology and Use of Nanomaterials
Outline
• Cement use in road construction
• Nanotechnology in cement– Roads and Transportation
• Cement nanotechnology – Multi-scale in cementitious materials
– Cement genome and molecular structures
– Cement molecular genome level • Modeling and simulations
• Experimental analysis
• Concluding Remarks
R. Mohan 2
US Interstate Highway System
• Over 4 million miles of
roads in the US • ~ 160 times the
distance around earth’s equator
• Over 45,000 miles forming the Interstate Highway System • ~1.8 times the
distance around earth’s equator
2006-3127 US Geological Survey – Department of Interior R. Mohan 3
Materials in Interstate Highway System
• Cement use exceeds asphalt use by ~ 35%
• 60% of the national highway system is paved with 11 inch thick concrete layer
Millions of metric tons
2006-3127 US Geological Survey – Department of Interior
R. Mohan 4
Concrete Pavement Road Map 2001
• A multi-agency coordinated by FHA to develop a long term plan for concrete pavement research and technology
• Vision – By 2020, the highway community will have a
comprehensive, integrated, and fully functional system of concrete pavement technologies that provides innovative solutions for customer driven performance requirements
R. Mohan 5
Nanotechnology in Cement Roads and Transportation
• Nanotechnology role and materials of interest – Placement and self-compacting properties
• Addition of super plasticizers to maintain high fluidity with low water/cement (w/c) ratio
– Improvement of compressive strength • Modification of micro/nano structure by nanomaterial additions
– Carbon nanotube (CNT)
– Nanoparticles (SiO2)
– Nano fibers (Nano cellulose)
– Structural/sensor monitoring • Hydration process
• Stress-strain state
• Degradation and damage
R. Mohan 6
Nanotechnology in Cement Road Construction
• Placement and self-compacting properties – Addition of super plasticizers
• Polycarboxylate ether polymers (PECs) • Beta naphthalene formaldehyde
– Allows keeping a low water/cement (w/c) ratio • Higher compressive strength and less shrinking • More workability of cement mixture
• Water causes the cement particles to attract one
another thickening the batch • Super plasticizers temporarily break the attraction by
attaching to the cement particles • As cement hydrates forming CH and CSH enclosing the
super plasticizers that can no longer function causing to thicken
• Fluidity controlled by amount of super plasticizers that can be added during the process
R. Mohan 7
Flocculating cement during hydration Steric repulsion caused by the super plasticizer
Super plasticizer at work
• The molecules of the super plasticizer adsorb on the surface of the cement components preventing flocculation during the hydration process
• Steric repulsion caused by the super plasticizer molecules guarantees higher workability and improved hydration of the cement
• Research efforts are oriented toward developing better super plasticizers and nano materials to enable using smaller w/c ratios without losing workability of the cement
Ref: Lafarge Group.
Cement Plasticizer mol.
Nanotechnology in Cement Super plasticizer effect
R. Mohan 8
Ref: Manzur-2010; Metaza- 2010.
Improvement of the compressive strength due to the addition of Multi-walled Nanotubes
Nanotechnology in Cement High Performance Cement
Multi-walled carbon nanotubes (MWNT) and Carbon nanofibers in cement paste
• Carbon nanotube • Carbon nanofibers
R. Mohan 9
Ref: Munoz-2010.
Effect of silica nanoparticles in compressive strength
Nanotechnology in Cement High Performance Cement
• Silica nanoparticles
R. Mohan 10
• Structural monitoring
– Embedded Nano/Micro sensors developed to monitor temperature patterns and moisture levels in concrete during hydration and early age.
• Nanotubes and nanofibers linked to wireless communication system are being developed to:
– Estimate stress and strain state in critical points of the bridges
– Detect crack formation and propagation
Nanotechnology in Cement Roads and Transportation
R. Mohan 11
• Other applications
Auto luminescent pavements using phosphorous nanoparticles
Ref: Jacobus-2008; Han-2009
Concrete blocks with embedded nanotubes can be used as traffic sensors Calibration of a nanotube-filled concrete block
Nanotechnology in Cement Roads and Transportation
R. Mohan 12
Cement Nanotechnology
• Cementitious materials at structural level – Properties and behavior governed by morphology
• Microstructure and nanostructure
• Nanomaterial additives modify and form new microstructures and nanostructures – Influences the fundamental molecular structures of
cementitious materials
• Need to understand the cement genome
Genome:
Molecular biology – entirety of organisms heredity information
Materials – Its basic constituent molecular structure
R. Mohan 13
Cementitious Materials
Level IV (concrete)
30 mm
Aggregate
(3mm-30mm)
Mortar
Level III (Mortar)
Cement paste
Sand particle
Unreacted
cement grains
2 mm
Cement – Concrete Microstructures
Presence of multi-scale features in cement – influences properties and behavior
R. Mohan 14
Micrographs : Bentz, NISTIR 5900 (1996)
Cementitious Materials
Cement Micro/Nano Structures
Level II (cement paste)
C-S-H matrix
300 μm
Unreacted
cement grains
(50μm-80μm)
Level I (genome)
300 nm
= C-S-H Gel
C-S-H solid
+
H2O filled
nano-pores
R. Mohan 15
Micrographs : Bentz, NISTIR 5900 (1996)
Cementitious Materials
• Innovations
• Understanding molecular structure and behavior
– Important and critical at nano scale and in nanotechnology applications
R. Mohan 16 H. Alkhateb (2012)
Cementitious Materials
• Hydration and formation of hydrated products
– Key for cement strength
• Basic elements in un-hydrated cement
Elements Source Clinker Composition Typical %
Calcium Limestone CaO 61-67%
Silicon Sand and or Clay SiO2 19-23%
Aluminum Bauxite Al2O3 2.5-6%
Iron Iron ore Fe2O3 0-6%
R. Mohan 17
Cementitious Materials
• Un-hydrated cement
Phase Chemical Structure Reactivity Properties
Alite (50-70%)
Ca3SiO5
Hydrates and hardens rapidly
Early Strength and initial set
Belite (15-30%)
Ca2SiO4
Hydrates and hardens slowly
Later Strength
Aluminate (5-10%)
Ca3Al2O3
High reactivity with water, liberates a large amount
of heat
Favored sulfate resistance
Ferrite C4AF (2
CaO(Al2O3.Fe2O3))
Less reactive compared to aluminate
Reduces clinkering
temperature
R. Mohan 18
Cementitious Materials
• Hydrated cement
– Water addition and hydration forms the hydrated products seen in the micro/nano structures
Phase Representation Volume %
Calcium Silicate Hydrates C-S-H 50-60%
Calcium Hydroxide CH 20-25%
Calcium Sulfo-aluminates CS 15-20%
C = CaO2; S = SiO2; H = H2O
R. Mohan 19
Multi-Scales and Modeling Approaches
20 R. Mohan
Cement Genome
• Un-hydrated and hydrated components
• Cement and nanotechnology
– Requires an understanding of cement genome molecular structures
– Computational nano scale modeling
• Potential method for such understanding
• Requires modeling at least at the cement genome molecular level
– Molecular Dynamics Modeling
R. Mohan 21
Molecular Dynamics Modeling
Forcefield Structure
Molecular Model
Energy Minimization
Molecular Dynamics
Statistical Mechanics
R. Mohan 22 H. Alkhateb (2012)
Cement Genome Level Modeling
• Molecular Dynamics Modeling of Un-Hydrated Cement Constituents
C3S C2S
Cement Constituent Current MD*
(GPa)
Literature Data
(GPa)
C3S
163.7
168.0 (Discover)
137.0 (Forcite) ( [1]
135.0 [2]
117.0 [3]
C2S 285.0 276.5 (Discover)
121.0 (Forcite) ( [1]
130.0 [2]
[1] J. Nanomechanics and Micromechanics, ASCE, June 2011
[2] Cement and Concrete Research, 31(4),555-561
[3] Cement and Concrete Research, 35(10),1948-1960
* Using Discover and COMPASS force field.
Predicted Modulus (E) and Comparisons
Figures show the molecular structures of two major un-hydrated cement constituents. Predictive
properties from the MD simulations are compared to the literature data. Published data are from nano-
indentation tests.
C3S: Tri-Calcium Silicate
C2S: Di-calcium Silicate
(C represents CaO2; S represents SiO2)
R. Mohan 23
• Property predictions at higher pressures (unhydrated components)
C3S
C2S
Predicted Modulus
0
200
400
600
800
1000
1200
1400
1600
1800
-200 0 200 400 600
Mo
du
lus
(Gp
a)
Pressure (Gpa)
Elastic
Bulk
shear
0
200
400
600
800
1000
1200
1400
1600
1800
-200 0 200 400 600
Mo
du
lus
(Gp
a)
Pressure (Gpa)
Elastic
Bulk
shear
Cement Genome Level Modeling
R. Mohan 24
• Molecular Dynamics Modeling of Hydrated Cement Constituents
Predicted Modulus (E) and Comparisons
Cement dispersed in water produces different
hydration products. Calcium-Silicate-Hydrate
(CSH) is the majority constituent. Though the
molecular structure of CSH and the break up is
not fully known, crystal structures of CSH are
closely related to the mineral crystals of
Tobermerite 14 𝐴 and Jennite
Tobermorite 14Å Jennite
Cement Constituent Current MD*
(GPa)
Literature Data
(GPa)
C.S.H (Tobermorite 14
Ǻ)
39.14 43.01 [1]
91.00 [2]
C.S.H (Jennite) 68.51 82.2 ( Discover)
66.9 (Forcite) ( [1]
66.0 [5]
[1] J. Nanomechanics and Micromechanics, ASCE, June 2011
[2] Phys. Stat. Sol. (a), 204(6), 1775-1780.
* Using Discover Material studio tool and COMPASS force
field.
Cement Genome Level Modeling
R. Mohan 25
• Molecular Dynamics Modeling of Hydrated Cement Constituents
Predicted Modulus
Tobermorite 14Å
Jennite
0
10
20
30
40
50
60
-0.2 0 0.2 0.4 0.6 0.8 1 1.2
Mo
du
lus
(Gp
a)
Pressure (Gpa)
Elastic
Bulk
shear
0
10
20
30
40
50
60
70
80
-1 0 1 2 3 4
Mo
du
lus
(Gp
a)
Pressure (GPa)
Elastic
Bulk
shear
Cement Genome Level Modeling
R. Mohan 26
• Modified C3S – CNT
c3s cnt-c3s
Tensile (GPa) 161.0 276.9
Poisson's ratio 0.340 0.3095
Bulk (GPa) 167.9 242.2
Shear (GPa) 60.06 105.7
Lamda 127.9 171.7
mu 60.06 105.7
Cement Genome Level Modeling
R. Mohan 27
• Primarily for structure, morphology, chemical and physical characteristics
– Morphology • Scanning Electron Microscopes (SEM)
• FIB - SEM(Focused Ion Beam - SEM)
• Atomic Force Microscopy
• Helium Ion Microscope
• Nanotom
• NMR (nuclear magnetic resonance) spectroscopy
-10
-5
0
5
10
15
20
0 1 2 3Forc
e (
N)*
10
E-8
Height( µm)
500nm
SEM
FIB SEM
NANOTOM AFM
Nanotechnology Experimental Analysis
R. Mohan 28
Nanotechnology Experimental Analysis
• Primarily for structure, morphology, chemical and physical characteristics – Characterization
• Nanoindentation
• X-Ray Diffraction (XRD)
• Thermo Gravimetric Analysis (TGA)
• Differential Scanning Calorimetry (DSC)
R. Mohan 29
Nanoindentation
DSC / TGA XRD
Nanotechnology in Cement
Concluding Remarks
• Nanomaterial inclusions have a potential to improve desirable properties for the transportation industry
• Fundamental understanding of cement materials and additives important for future enhancements
• Multi-scale nature
– Integrated computational material science and engineering
• Modeling and experimental processes
R. Mohan 30
Contact Details
Acknowledgements: Research support from federal agencies; JSNN, researchers and students
Ram Mohan, Ph.D.
Associate Professor
Department of Nanoengineering
Joint School of Nanoscience and Nanoengineering
2907 E Lee Street
North Carolina A&T State University
Greensboro, NC 27401
Phone: (336) 285 – 2867
E-mail: [email protected]
http://jsnn.ncat.uncg.edu
R. Mohan 31
