increased sustainability of asphalt through fiber
TRANSCRIPT
8/3/2011
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Increased Sustainability of Asphalt Through Fiber-Reinforcement
Co-Sponsors: OK Hardware & Construction Supply
Hawaii Asphalt Paving Industry (HAPI)University of HawaiiFORTA Corporation
Honolulu International AirportDepartment of Transportation
State of Hawaii
August 2, 2011
Kamil E. Kaloush , Ph.D., P.E.
Agenda• Sustainability
• Asphalt Modifiers
• Fiber Reinforced Asphalt Concrete (FRAC)
– Boeing, Mesa, AZ
– Evergreen Drive, Tempe, AZ
• Independent ASU research efforts
– Airport Cooperative Research Program (ACRP) Graduate Student Award Program
– Dosages and lab mixing studies
• Other projects and fiber addition techniques (FORTA)
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Michael M. Crow
President, Arizona State University
“sustainability represents one of the most challenging
interface problems in science today.
the design of a sustainable interface between the natural
environment and the built or designed environment is as
essential to our collective well-being as any intellectual
pursuit of the age.”
u-pass, light rail, zipcar, bike co-op
energy, water, toxins and pollutants, bio-based products, landscaping,
forest conservation, recycling, packaging, green building
water
building and grounds
waste and recycling
Practicing
purchasing and policy
transportation
aramark, engrained
sustainability
food services
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Criteria for Sustainable Pavements?
• Performance / Durability
– Material / Design
• Safety
• Ride Quality or Comfort
• Life Cycle Cost
• Energy Consideration
• Quality of Life Issues
– Highway Noise
– Air Quality
– Urban Heat Island
• Recyclability
Expert Panel Ratings
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U.S. Green Building Council’s Rating System
Leadership in Energy and Environmental Design (LEED™)
LEED Rating System
• Sustainable Sites
• Water Efficiency
• Energy and Atmosphere
• Materials & Resources
• Indoor Environmental Quality
• Innovation & Design Process
For more information: www.usgbc.org
1st LEED Platinum in AZ:
The Arizona Biodesign
Institute at ASU
TRB on Transportation and Climate Change
“Reducing transportation-related emissions of carbon dioxide--the primary greenhouse gas--that contribute to climate change and adapting to the consequences of climate change will be among the biggest public policy challenges facing the transportation profession over the coming decades. “
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US GHG Estimates• Fact: coal is the primary generator of
electricity (~50%) in the US
• Electric power generation: ~80% of total GHG emissions , EPA 2006
• Transportation Sector: 15-30%
• Pavements??? – Raw materials production, manufacturing, placement,…
Model
Y
TpDiMnPnDnWTkmEqkgCOannualTotal
***1000**/.2
Where,T = thickness of pavement layer, metersW = width of road, metersDn = density of pavement material, kg/m3
Pn = material production value, kg CO2 Eq. /kg Mn = material mixing value, kg CO2 Eq. /kg Di = distance from material production site to application site, kmTp = transport from production site to application site value, kg CO2 Eq. /kg material-kmY = road life, years
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CO2 Emissions
12
Why are Modifiers Used?
• Mitigate both traffic- and environmentally induced HMA pavement distresses
– Rutting resistance
• Stiffer asphalt binders at warm temps
– Thermal cracking
• Inhibit crack propagation– Internal elastic network (polymers)
– Crack pinning (solid particles)
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13
Types of Modifiers
• Polymers
– Plastomers
– Elastomers
• Fillers
– Gilsonite
– Mineral fillers
• Polyester, asbestos, glass, polypropylene, carbon, cellulose, kevlar and 31 recycled waste fibers
Modifiers in HMA mixtures• Rock wool
• Polyester fiber
• Cellulose fiber
• Crumb rubber Tire Fiber
Crumb Rubber
Cellulose Fiber
(Chowdhary et al., FORTA®)
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Fibers in Asphalt Concrete• History of Fibers
– Wire mesh (Zube, 1956).
– Modern development in 1960s
– 1995-96, Chrysolite, rock wool, glass wool, cellulose and
nylon fiber
• Merits of fibers in AC mixtures
– Enhanced load carrying capacity
– Rutting resistance
– Resistance to cracking and fatigue
– Higher asphalt content – resistance to moisture damage
& aging
– More flexibility, lower strength and stiffness
– Asphalt drain down reduction
16
Common Polymer Chains
Diblock Copolymer
Triblock Copolymer
Random Block Copolymer
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17
SBS Polymersin Asphalt Binders
Step 1
Step 2
Step 3
PolymerPolymer in
hot AC
Polymer in
cool AC
Styrene
ButadieneStroup-Gardiner, M., and Newcomb, D.E. Polymer Literature Review. Minnesota
Department of Transportation Report MN/RC – 95/27. Sept. 1995.
Bahia. H.U., Hanson, D.I., Zeng, M., Zhai, H., Khatri, M.A., Anderson, R.M.
NCHRP Report 459-Characterization of Modified Asphalt Binders in Superpave
Mix Design. Transportation Research Board, National Research Council. 2001.
18
TEM Microphotographs
2% Linear SBS 4% Linear SBS
White area = Asphalt Binder and Black area = polymer
500 nm 500 nm
Stroup-Gardiner, M., and Newcomb, D.E. Polymer Literature Review. Minnesota Department of
Transportation Report MN/RC – 95/27. Sept. 1995.
Bahia. H.U., Hanson, D.I., Zeng, M., Zhai, H., Khatri, M.A., Anderson, R.M. NCHRP Report 459-
Characterization of Modified Asphalt Binders in Superpave Mix Design. Transportation Research
Board, National Research Council. 2001.
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19
TEM MicrophotographsWhite area = Asphalt Binder and Black area = polymer
4% Radial SBS
Stroup-Gardiner, M., and Newcomb, D.E. Polymer Literature Review. Minnesota Department of
Transportation Report MN/RC – 95/27. Sept. 1995.
Bahia. H.U., Hanson, D.I., Zeng, M., Zhai, H., Khatri, M.A., Anderson, R.M. NCHRP Report 459-
Characterization of Modified Asphalt Binders in Superpave Mix Design. Transportation Research
Board, National Research Council. 2001.
Evaluation of FORTA Fiber-Reinforced Asphalt Mixtures Using
Advanced Material Characterization Tests – Arizona
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Fiber Reinforced HMA ?
FORTA® Manufacturer of Synthetic Fibers for Concrete and Asphalt
Developed Asphalt fibers in 1982
Three-dimensional reinforcement of HMA
FORTA® AR® Fiber
FORTA® AR® FiberSynergistic blend of collated fibrillated Polypropylene and Aramid fibers
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FORTA® AR®
Polypropylene
• Chemically Inert
• Non-Corrosive
• Non-Absorbent
Aramid
•High Tensile Strength
•Non-Corrosive
•High Temperature Resistance
Physical Characteristics of the FibersMaterials Polypropylene Aramid
FormTwisted Fibrillated
Fiber
Monofilament
Fiber
Specific Gravity 0.91 1.45
Tensile Strength (MPa) 483 3000
Length (mm) 19.05 19.05
Color tan yellow
Acid/Alkali Resistance inert inert
Decomposition
Temperature ( C)157 >450
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Why ASU ?
• National Studies since 1999. – NCHRP 9-19 / MEPDG
• Large database of HMA Engineering Properties
• Recognized Research Support:NCHRP - ADOT – FORD Maricopa County - Texas DOT,
Caltrans – Canada, Sweden, Brazil
ObjectivesConduct an advanced laboratory experimental
program to obtain typical engineering materialproperties for FORTA fibers reinforced asphaltmixtures using the most current laboratory testsadopted by the pavement community.
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Two Projects
• Boeing Mixture –Pilot Study
• City of Tempe –Evergreen Drive
Binder Mix Design Data Mix Type
Binder Type Design AC (%) Target Va (%) Gmm
FORTA Boeing PHX D-1/2 PG 70-10 5.10 7 2.4605
Binder Mix Design Data Mix Type
Binder Type Design AC (%) Target Va (%) Gmm
PHX C-3/4 Control PG 70-10 5.00 7 2.428
PHX C-3/4 1 lb/Ton PG 70-10 5.00 7 2.458
PHX C-3/4 2 lb/Ton PG 70-10 5.00 7 2.471
Evergreen Drive
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Evergreen Drive as Constructed
Pavement Ctr Ctl 1-F Ctl
Mid Portion 1-F 2-F 1-F Ctl
Curb Side 1-F
1-F
FORTA Project: Evergreen Test Section, City of Tempe, Arizona
1-F 1-F Ctl 2-F
-2.5
0, Fire
Hydrant
40 86 132 186 211
-2.5
-2.5
30 86 139 179 211
2116 53
1-F
2-F
Ctl
1-lb of FORTA Fibers per ton
2-lbs FORTA Fibers per ton
Control Mix without FORTA Fibers
8' Curb Side
8' Middle Portion
8' Pavement Center
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ASU Materials Characterization Program
• Laboratory testing procedures and models to predict performance.
• How do we truly capture the known field performance in the laboratory?
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Laboratory Tests
• Binder Tests
• Triaxial Shear Strength
• Dynamic Modulus
• Permanent Deformation– Repeated Load
– Static Creep
• Beam Fatigue
• Indirect Tensile Strength and Creep
• Fracture and Crack Propagation
Polypropylene Modified Binder
Mix time and temperature:
Time: 30 min
Temperature: 329 and 365 °F
(165-185 °C)
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Conventional Tests
Superpave /
SHRP Tests
Penetration AASHTO T49-93
Softening Point AASHTO T53-92
Rotational Viscosity AASHTO TP48
Dynamic Shear
Rheometer (DSR):
AASHTO PP1
Bending Beam Rheometer
(BBR): AASHTO TP1-98
Binder Tests
Viscosity - Temperature Relationship (Original Binder)
ARAC PG 58-28: y = -2.4795x + 7.6903
R2 = 0.989
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
2.70 2.75 2.80 2.85 2.90 2.95
Log (Temp, oRankine)
Lo
g (
Lo
g v
isco
sity
, cP
)
(41) (103) (171) (248) (335) (432)(deg F)
Pen
59, 77oF
Soft. Point
139oF
Brookfield Viscosity
200-350oF
Viscosity – Temperature
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BINDER TEST RESULTSViscosity
y = -3.37x + 10.14
R2 = 0.99
y = -3.88x + 11.51
R2 = 0.99
y = -3.84x + 11.45
R2 = 1.00
y = -3.63x + 10.87
R2 = 1.00
0.0
0.2
0.4
0.6
0.8
1.0
1.2
2.70 2.75 2.80 2.85 2.90
Log (Temp) (Rankine)
Lo
g (
Lo
g v
isco
sity)
(cp
)FORTA Modified
PG 64-22 PG 70-10 PG 76-16
BINDER TEST RESULTS
Temperature - Viscosity Relationship for:
FORTA Virgin and Modified Binders
1 lb/Ton
y = -3.6589x + 10.949
R2 = 0.9965
2 lb/Ton
y = -3.3896x + 10.2
R2 = 0.9875
Virgin
y = -3.6529x + 10.919
R2 = 0.9981
0.000
0.200
0.400
0.600
0.800
1.000
1.200
2.70 2.75 2.80 2.85 2.90 2.95
Log (Temp) (oR)
Lo
g L
og
(V
isc)
(cP
)
Virgin 1 lb/Ton 2 lb/Ton
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Mixture Tests
Modulus
Permanent
Deformation
Indirect Tensile Creep
Flexural Fatigue
Field Laboratory Mixes
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Field Laboratory Mixes
Visual Observation
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60X10X
60X200X
Figure 9. Mohr-Coulomb Envelope for Cell 22, T = 37.7oC (100
oF)
= 0.7487* + 15.0 (
R2 = 0.98
0
20
40
60
80
100
120
140
160
0 50 100 150 200 250 300 350 (psi)
(p
si)
Sigma3 = 0
Sigma3 = 20 psi
Sigma3 = 40 psi
Sigma3 = 60 psi
Figure 10. Mohr-Coulomb Envelope for Cell 22, T = 54.4oC (130
oF)
= 0.8532* + 4.4 (
R2 = 1.00
0
20
40
60
80
100
120
140
160
0 50 100 150 200 250 300 350 (psi)
(p
si)
Sigma3 = 0
Sigma3 = 20 psi
Sigma3 = 40 psi
Sigma3 = 60 psi
Triaxial Shear Strength Tests
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Triaxial Shear Strength Results
Fiber-Reinforced Asphalt
= 66.12 + 0.577
c = 66, = 30o
MnRoad Cell 16
= 9.13 + 0.8057
c = 9, = 39o
0
20
40
60
80
100
120
140
160
0 20 40 60 80 100 120 140 160
Normal Stress, (psi)
Sh
ea
r S
tress
, (
psi
)
(b)
Boeing
EvergreenMohr-Coulomb Failure Envelope
FORTA Control
y = 1.0793x + 27.541
R2 = 0.9976
c = 27.541
= 47.2o
FORTA Evergreen One Pound
y = 1.122x + 34.604
R2 = 0.9998
c = 34.6
= 48.3o
FORTA Evergreen Two Pound
y = 0.967x + 43.938
R2 = 0.972
c = 43.9
= 44o
0
20
40
60
80
100
120
140
160
0 20 40 60 80 100 120
Normal Stress (PSI)
Sh
ea
r S
tre
ss(P
SI)
TRIAXIAL SHEAR STRENGTH TEST
0
500
1000
1500
2000
2500
3000
0 100 200 300 400 500 600 700 800Time, sec
Str
ess
, k
Pa
40-psi Confinement
20-psi Confinement
0-psi Confinement
(a)
0
200,000
400,000
600,000
800,000
1,000,000
1,200,000
1,400,000
1,600,000
1,800,000
2,000,000
0 kPa (0 psi) 138 kPa (20 psi) 276 kPa (40 psi)
Are
a u
nd
er t
he
Cu
rve
(kP
a-s
ec)
Control 1 lb/Ton 2 lb/Ton
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DYNAMIC COMPLEX MODULUS (E*)
- E* = Dynamic Complex Modulus = o / o
- o = peak dynamic stress amplitude (kPa / psi)
- o = peak recoverable strain (mm/mm or in/in)
- = phase lag or angle (degrees) = VISCOELASTIC PROPERTY
Time
t
t
Str
ess
-Str
ain
, ε
, ε
, ε
, ε
, ε
, ε
, ε
Str
ess
-Str
ain
, ε
, ε
, ε
, ε
, ε
, ε
, ε
Str
ess
-Str
ain
, ε
, ε
, ε
, ε
, ε
, ε
, ε
Str
ess
-Str
ain
, ε
, ε
, ε
, ε
, ε
, ε
, ε
Str
ess
-Str
ain
, ε
, ε
, ε
, ε
, ε
, ε
, ε
Str
ess
-Str
ain
, ε
, ε
, ε
, ε
, ε
, ε
, ε
Str
ess
-Str
ain
, ε
, ε
, ε
, ε
, ε
, ε
, ε
Str
ess
-Str
ain
, ε
, ε
, ε
, ε
o o
o sin( t – )
o sin( t)
E* MASTER CURVEConstruction of Master Curve - Average of Three Replicates, FORTA
Conventional Mix
1.E+04
1.E+05
1.E+06
1.E+07
-6 -4 -2 0 2 4 6Log Reduced Time, s
E*
psi 14 F
40 F
70 F
100 F
130 F
Predicted
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E* MASTER CURVE
1.E+04
1.E+05
1.E+06
1.E+07
-4 -3 -2 -1 0 1 2 3 4Log Reduced Time, s
E*
psi
1 lb/Ton
2 lb/Ton
Control
E* TEST RESULTS
747,179
479,964
1,097,269
242,350133,365148,180
0
200,000
400,000
600,000
800,000
1,000,000
1,200,000
Salt River 3/4" PG70-10 Salt River 3/4" PG64-22 Fiber-Reinforced
E*
, p
si
100 F 130 F
Evergreen
Boeing
4,027,411
5,132,366
2,981,436
803,000
1,500,000
818,000
209,000466,000294,000
0
1,000,000
2,000,000
3,000,000
4,000,000
5,000,000
6,000,000
7,000,000
Control 1 lb/Ton 2 lb/Ton
E*
, p
si
40 F 100 F 130 F
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27
Repeated Load Permanent Deformation Tests
Secondary
Primary
Tertiary
FN Defines N/Time When
Shear Deformation Begins
Repeated Load Permanent Deformation Test (Flow Number)-Fiber Reinforced Asphalt
0.0
0.4
0.8
1.2
1.6
2.0
2.4
0 20000 40000 60000 80000 100000
Cycles, N
Acc
um
ula
ted
Str
ain
(%
) WesTrack Section 19
Fiber-Reinforced Asphalt
(a)
Boeing
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28
0.0000
0.0020
0.0040
0.0060
0.0080
0.0100
0.0120
0 5000 10000 15000 20000 25000
Number of Cycles during the Tertiary Stage
Ax
ial
Str
ain
Slo
pe
FEC02
FEC03
FEC04
FE101
FE102
FE104
FE202
FE203
FE204
2 lb/Ton
Control
1 lb/Ton
Flow Number-Evergreen Dr.
Static Creep Results
401
2,155
3,678
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
Control 1 lb/Ton 2 lb/Ton
Flo
w T
ime (
Sec)
1.15
0.16
0.055
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Control 1 lb/Ton 2 lb/Ton
Slo
pe
of
Cre
ep C
om
pli
an
ce,
m
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Flexural Fatigue Tests
SHRP M-009
Fatigue Cracking Tests
32
111
kk
t
fE
KN
Fatigue Cracking TestsComparison of the FORTA 2 lb/Ton Mixes at Control Strain and 40,70 and 100oF
and at 50% of Initial Stiffness
y = 0.002x-0.1851
R2 = 0.9412
y = 0.0007x-0.1155
R2 = 0.9408y = 0.0009x
-0.1646
R2 = 0.9643
1.E-05
1.E-04
1.E-03
1.E-02
1.E+03 1.E+04 1.E+05 1.E+06 1.E+07
Cycles to Failure
Str
ain
Lev
el
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30
TEST RESULTS – Boeing Mix
Comparison of the FORTA Evergreen Mixtures at Control Strain and 70 oF and at
50% of Initial Stiffness
FORTA Control 70 °F
y = 0.0017x-0.1898
R2 = 0.9385
FORTA 1 lb/Ton 70 °F
y = 0.0011x-0.1604
R2 = 0.9592
FORTA 2 lb/Ton 70 °F
y = 0.0007x-0.1155
R2 = 0.9408
1.E-05
1.E-04
1.E-03
1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07
Nf, Cycles to Failure
Str
ain
Lev
el
Test Results - Evergreen
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524,371
4,426,113
637,384
0
500,000
1,000,000
1,500,000
2,000,000
2,500,000
3,000,000
3,500,000
4,000,000
4,500,000
5,000,000
Control 1 lb/Ton 2 lb/Ton
Nf
Un
til
Fa
ilu
re
Comparisons at 70F and 250 micro-strains
1,152
1,0491,110
0
200
400
600
800
1,000
1,200
1,400
Control 1 lb/Ton 2 lb/Ton
Init
ial
Sti
ffn
ess
(ksi
)
Flexural Strength and Post Peak Energy
Force vs Deflection-FEC20
0
50
100
150
200
250
300
0.000 0.050 0.100 0.150 0.200 0.250 0.300
Deflection, in
Fo
rce,
Lb
s
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Comparative Plot – Cyclic LoadComparative Plot
0
50
100
150
200
250
0.000 0.050 0.100 0.150 0.200 0.250 0.300
Deflection (in)
Fo
rce (
lb)
Control
1 lb/Ton
2 lb/TonPeak =176 lb
Peak = 170 lb
Peak = 111 lb
Residual Strength and Post Peak Energy
242.6277.4
188.1
67.7
110.8
82.5
310.3
388.1
270.6
0.0
50.0
100.0
150.0
200.0
250.0
300.0
350.0
400.0
Str
eng
th (p
si)
Flexural Residual Corrected Flexural
Control
1 lb/Ton
2 lb/Ton
Mix Specimen
ID
Peak
Load
(lb)
Flexural
Strength
(psi)
Post Peak
Energy
(lb-in)
Residual
Strength
(psi)
Corrected
Flexural
Strength (psi)
Control Average 164.9 242.6 14.2 67.7 310.3
1 lb/Ton FE106 171.4 277.4 17.6 110.8 388.1
2 lb/Ton FE204 111.1 188.1 11.2 82.5 270.6
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Indirect Tension Tests
• Disk shape specimen (6.0 x 1.5 inch) with vertical and horizontal LVDTs on both sides
• The tensile creep– Three temp: 0, -10, and -20oC
– Static load along the diametral axis of a specimen
– Deformations used to calculate tensile creep compliance as a function of time
• The tensile strength– Determined immediately after the tensile
creep test
– Constant rate of vertical deformation to failure
Indirect Tensile Tests Loading Frame and
Specimen with LVDTs
Creep Compliance Master CurvesCreep Compliance Master Curve
1E-07
1E-06
1E-05
1E-04
1E+00 1E+01 1E+02 1E+03 1E+04 1E+05 1E+06 1E+07
Reduced Time
Cre
ep
Co
mp
lia
nc
e (
1/p
si)
FORTA Evergreen Control FORTA Evergreen 1 lb-Ton FORTA Evergreen 2 lb-Ton
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Tensile Strength - EvergreenTENSILE STRENGTH OF FORTA EVERGREEN MIXES
371
408410
610
571
468
598
579
467
300
350
400
450
500
550
600
650
700
0 10 20 30 40 50 60
TEMPERATURE (oF)
TE
NS
ILE
ST
RE
NG
TH
(p
si)
FEControl FE1lb-Ton FE2lb-Ton
Energy Until FailureENERGY UNTIL FAILURE OF FORTA EVERGREEN MIXES
96.7110.6
178.2
257.0213.4
182.0
280.9
205.3180.6
0
50
100
150
200
250
300
0 10 20 30 40 50 60
TEMPERATURE (oF)
EN
ER
GY
UN
TIL
FA
ILU
RE
(lb
s-p
si)
FEControl FE1lb-Ton FE2lb-Ton
V ER TICAL D EFO RM A TION
LO
AD
(lb
s)
Ene rgy until Failure
Area under curv e till max load
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Total Fracture EnergyTOTAL FRACTURE ENERGY OF FORTA EVERGREEN MIXES
279.3
163.2
113.0
198.0
284.5430.4
206.7
294.3
550.6
0
100
200
300
400
500
600
700
0 10 20 30 40 50 60
TEMPERATURE (oF)
TO
TA
L F
RA
CT
UR
E E
NE
RG
Y (
lbs-
psi
)
FEControl FE1lb-Ton FE2lb-Ton
V ER TICA L DEFO R M A TION
LO
AD
(lb
s)
Fractur e Energy
Are a under cur ve
Comparison of Indirect Tensile Strength at 5 Temperatures
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
-10 0 10 21.2 37.8
Ind
irect T
en
sile
Str
en
gth
, N/m
m2
Temperature, °C
IDT Comparison
Control 1 lb/ton 2 lb/ton
8/3/2011
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MEPDG Thermal Cracking Model (TCModel)
Pavement
Response Model
Stress due to Cooling
Crack Depth
Fracture Model
Crack Propagation
Probability-Based
Model
Amount of Thermal Cracks /
Unit Length of Pavement
Crack Depth Fracture Model• The Paris law for crack propagation
nKAC
where:
C = change in the crack depth due to a cooling cycle
K = change in the stress intensity factor due to a cooling cycle
A, n = fracture parameters
Experiments by Molenaar led to the following
relationship:)n*St*Elog(*52.2389.4Alog
Experiments by Lytton led to the following
relationship:m
11*8.0n
8/3/2011
37
Thermal Cracking Prediction from MEPDG
Thermal Cracking: Total Length Vs Time
0
300
600
900
1,200
1,500
1,800
2,100
2,400
2,700
3,000
0 12 24 36 48 60 72 84 96 108 120
Pavement Age (month)
To
tal L
en
gth
(ft
/mi)
Gap Graded Asphalt Rubber
Conventional HMA
Fracture Energy: Conventional Vs. Asphalt Rubber
Total Fracture Energy @ -10
oC
Conventional vs Rubber Asphalt Mixture
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
9,000
10,000
0.00 0.05 0.10 0.15 0.20 0.25 0.30
Vertical Deformation [in]
Lo
ad
[lb
f]
Conventional HMA
Gap Graded Rubber Asphalt
fract = 263 lb*inch
fract = 588 lb*inch
St = 454 psi
St = 494 psi
)n*St*Elog(*52.2389.4Alog
8/3/2011
38
Comparison of Post-Peak Fracture Energy at -15oC
237
268 287
139
357
279
272
277
221
297
136
36
16 23
14 22 28
14 16 3
4
16
17
51
0
50
100
150
200
250
300
350
400
Jack
rabbit
AR-A
CFC
PG58-
22
Two G
uns AR-A
CFC
PG58
-22
Silv
er S
prings A
R-A
CFC
PG58
-22
Badger
AR-A
CFC
PG58
-22
Alb
erta
II A
RAC 2
00-3
00 P
EN A
V11%
Alb
erta
II A
RAC 2
00-3
00 P
EN A
V8%
Alb
erta
II A
RAC 2
00-3
00 P
EN A
V5%
Badger
Spri
ngs ARAC P
G58-
22
Jack
rabbit
ARAC P
G58
-22
Two G
uns ARAC P
G58-
22
Alb
erta
II 3
/4" 200
-300
PEN
Bid
ahouch
i 3/4
" PG58
-28
Bid
ahouch
i Bas
e PG58
-28
Bid
ahouch
i 3/4
" PG64
-22
Sal
t Riv
er 3
/4" PG
64-22
Bid
ahouch
i Bas
e PG64
-22
Jack
rabbit
3/4"
PG
64-2
2
Sal
t Riv
er B
ase PG64-
22
Two G
uns 3/4"
PG64-
22 P
lant
Sal
t Riv
er B
ase PG76-
16
Sal
t Riv
er 3
/4" PG
76-16
Sal
t Riv
er B
ase PG70-
10
Badger
Spri
ngs 3/4"
PG70-
10
En
erg
y, lb
s*i
n
“A” in Crack Depth Fracture Model
• “A” developed by Molenaar:
)n**Elog(*52.2389.4Alog m
nKACn Paris crack growth law:
n “A” developed by Schapery:t
0
n
m/1
1
2
2
1
2
m
dt)t(w2
D)1(
I6A
where:
n = 2[1 + (1/m)]
σm = tensile strength
I1 = value of the integral of the dimensionless stress-strain curve of the material
ν = Poisson’s ratio
D1 = intercept of the creep compliance curve
m = slope of the creep compliance curve
Γ = fracture energy
w(t) = the normalized waveform of the applied load with time
Δt = period of the loading to complete one cycle of loading
8/3/2011
39
Predicted Thermal Cracking - Fargo, ND
Old Vs. New A Parameter
Two Guns AR-ACFC
0.0
500.0
1,000.0
1,500.0
2,000.0
0 12 24 36 48 60 72 84
Time, Month
Th
erm
al
Cra
ckin
g,
ft/m
ile
Old "A"
New "A"
C* LINE INTEGRAL TEST OBJECTIVE
Evaluate crack growth behavior of time
dependent materials and compare crack
potential of modified asphalt mixes
8/3/2011
40
C* TEST SET UP
• From Gyratory: 6 in
diameter cut to ~1.8 in thick
• A right-angled wedge cut to
a depth of 1 in. extend over
the entire thickness.
• A small, artificial crack was
sawed at the tip of the
wedge (notch) to channelize
crack initiation.
• Test conducted at 21°C
FRACTURE AND CRACK GROWTH MODEL -C* LINE INTEGRAL
• C* Line Integral–analog of the Jintegral where strains anddisplacement replaced by their rates(time dependent materials)
• Defined as the difference of 2identically loaded bodies havingincrementally differing crack lengths
dU*=Change in energy rate for a load P and a crack extension dC
B=thickness
dC
dU
BC
*1*
8/3/2011
41
C* MULTIPLE SPECIMENS METHOD
• Specimens
subjected to
different constant
displacement
rates
• Load and crack
length measured
as a function of
time
T (time)
P (
Lo
ad
)
a (
cra
ck
le
ng
th)
Step 1
a
P
(displacement rate)
P (
Lo
ad
)
Step 2
a1
a2
a3
a1>a2>a3
Load vs displacement rate for fixed crack length
Area under the curve= rate of work done U* per unit of crack plane thickness
a (Crack Length)
U*
(En
erg
y R
ate
)
Step 3
1
2
3
1< 2< 3
Crack growth rate are plotted versus crack length
(displacement rate)
C*
Lin
e In
teg
ral
Step 4
Area under the
curve ( Step 3) is
plotted against
crack length
Slope of curve is
C*
Crack growth rate is
plotted as a function
of C*
The higher the slope
the more resistant the
material
C*
Lin
e In
teg
ral
Step 5
ȃ (Crack Growth rate)
C* LINE INTEGRAL-Literature Results
Abdulshafi and Kaloush
(1988)
8/3/2011
42
C* LINE INTEGRAL
BENEFITS / POTENTIAL IMPLEMENTATION
• Useful for comparative purposes.
• Simple: sample geometry, equipment.
• Logical behavior / trend: the more energy required and
the slower the crack speed, the better the mixture resist
cracking
• Procedure: makes use of Gyratory Compacted specimens,
or field cores from existing pavements can be utilized.
• Potential incorporation within other existing models
(such as the IDT thermal cracking models) to provide
input on crack speed propagation.
8/3/2011
43
ACTUAL TEST PERFORMED20 minutes
Post Test Failure
8/3/2011
44
Variability Issues
281
5,696
32,091
0
20,000
40,000
60,000
80,000
100,000
120,000
Control 1 lb/Ton 2 lb/Ton
Flo
w N
um
ber
(C
ycl
es)
FN for 1 lb/Ton mix - 115 times higher
than the control mix
FN for 2 lb/Ton - 20 times higher than
control mix
High Variability
10 100 1,000 10,000 100,000 1,000,000
Range of Log Flow Number (Cycles)
Control
1 lb/Ton
2 lb/Ton
Tertiary
Cycles (N)
Primary Secondary
Perm
an
en
t S
train
(p)
FN
Tertiary region
commences
Fibers Extraction
xylene, toluene and trichloroethylene
8/3/2011
45
Centrifuge Procedure
Fibers Recovery
8/3/2011
46
Microscopic Observations of Recovered Fibers
Summary – Extraction
• Fiber extraction Process– Good estimate of actual fiber content
– Quality Control / Quality Assurance
• Actual and Design Fiber Content– 1 lb/ton, Statistically significant difference
– 2 lb/ton, Statistically insignificant difference
• Binder Content and Aggregate gradation –– Experimental and target values in close
proximity
8/3/2011
47
Summary Overall
– The viscosity-temperature susceptibility relationship showed positive and desirable modification process.
– Higher fracture energy represented by peak and post peak failure in the triaxial tests
– Gradual accumulation in permanent strain in the permanent deformation tests, and higher tertiary flow values => desirable properties to resist rutting.
– 1.5 to 2 times higher Dynamic Modulus E* values compared to the conventional mixtures. Higher moduli at high temperatures are indicative of better resistance to permanent deformation or rutting.
– Higher fatigue life compared to conventional mixes.
– higher crack propagation resistance as represented by the C*-Line Integral test procedure.
USE of Data in the MEPDG
“The overall objective of the Guide for the Mechanistic-
Empirical Design for New and Rehabilitated
Pavement Structures is to provide the highway
community with a state-of-the-practice tool for the
design and rehabilitated pavement structures, based
on mechanistic-empirical principles.”
8/3/2011
48
MEPDG:
An Analysis Method
An Iterative Design Method
The output is:
An amount of distress over time
Fatigue Cracking
Thermal Cracking
Longitudinal Cracking
IRI
Rutting
Predicted Distresses
8/3/2011
49
Design Process
Climate Inputs
EICM
Material Properties
Transfer Functions
Predicted Performance Mechanistic Analysis
Traffic
Mechanistic-Empirical Pavement Design
Guide-MEPDG
Relates pavement material characteristics with their
performance in the field
Calibrated based on data from the LTPP Project.
Capability to adapt to local conditions
New & rehabilitated pavement designs
8/3/2011
50
Hierarchical Design Inputs in the
MEPDG
Level 1: Accurate data from laboratory testing
Level 2: Intermediate level of accuracy. Inputs estimated through correlations
Level 3: Lowest level of accuracy. Default values provided by the program
Approach Description
• A total of 10 runs were performed for each of the control and fiber reinforced asphalt (1 lb/ton) mixtures as follows:
- 2 Traffic Levels, 1500 and 7000 AADT (intermediate and high traffic)
- 5 Different Asphalt Concrete (AC) layer thicknesses (2-6 in)
• Project Location: Phoenix
• Design Life: 10 years
• Distress Evaluated: Rutting and Fatigue Cracking
AC Layer 2-6 in
Base-8 in (29,000psi)
Subgrade (15,000 psi)
8/3/2011
51
AC Rutting Only Vs. Thickness - Results
AADT=7000 ~50,000,000 ESAL’s
AADT = Annual Average Daily Traffic
ESAL = Equivalent Single Axle Load
AADT=1500 ~10,000,000 ESAL’s
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0 1 2 3 4 5 6 7
Thickness (in)
AC
R
utt
ing
(in
)
Control 1 lb/Ton
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0 1 2 3 4 5 6 7Thickness (in)
AC
R
utt
ing
(in
)
Control 1 lb/Ton
0
0.1
0.2
0.3
0.4
0.5
0.6
0 1 2 3 4 5 6 7
Thickness (in)
To
tal R
utt
ing
(in
)
Control 1 lb/Ton
Total Pavement Rutting Evaluation
To reach no more than 0.4 inches of rutting
during a design period of 10 years, a
control AC pavement thickness would
require 5.5 inches; whereas the fiber
reinforced AC layer thickness needed
would be only 3.5 inches; a saving of 2
inches.
Similarly for an intermediate
traffic analysis, the saving
would be 1.5 inches of AC
layer thickness
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 1 2 3 4 5 6 7
Thickness (in)
To
tal R
utt
ing
(in
)
Control 1 lb/Ton
AADT=7000~50,000,000 ESAL’s
AADT=1500~10,000,000 ESAL’s
8/3/2011
52
Fatigue Cracking Evaluation
AADT=7000~50,000,000
ESAL’s
AADT=1500~10,000,000
ESAL’s0
1
2
3
4
5
6
7
0 1 2 3 4 5 6 7Thickness (in)
Fa
tig
ue
(%
)
Control 1 b/Ton
0
0.2
0.4
0.6
0.8
1
1.2
0 1 2 3 4 5 6 7
Thickness (in)
Fa
tig
ue
(%
)
Control 1 lb/Ton
Fatigue Cracking analysis also show
similar trends, but it is also dependent on
the AC layer thickness (thin versus thick).
The amount of Fatigue cracking predicted
for intermediate level traffic (below) is
insignificant.
Summary of Findings
• FORTA fiber reinforced asphalt mixture performs better
than the control mixture against Rutting and Fatigue
irrespective of the thickness of the AC layer.
• This performance can be translated to savings in the
asphalt layer thickness.
– For the rutting distress criteria, reduced AC layer thickness of
about 1.5 to 2 inches can be achieved, depending on the traffic
level of the roadway.
– For Fatigue Cracking, the greatest potential is associated with
asphalt layers that are typically in the 3 to 5 inches thickness
range.
8/3/2011
53
Field Cracking
8/3/2011
54
8/3/2011
Interesting Field Maintenance
Boeing – Mesa, AZ
infield placed in 2008
2010, broken pipe caused a sink 2.5’ W x 8’ L x 2.5” D
Only (1) 10” crack found
8/3/2011
55
8/3/2011
Interesting Field MaintenanceAsphalt saw-cut & removed in 2 pieces 3’W x 8’L x 2”Thick
One center anchor on 560lbs slab
Removed in one piece!
8/3/2011
Jackson Hole Airport - Jackson,
WY 5/09
FORTA-FI was used in a 1 1/2" porous friction course. It is located in Grand Teton National Park
35,000 flights annually, >300,000 enplanements
8/3/2011
56
8/3/2011
Jackson Hole Air Port - Jackson, WY 5/09
6,450' (1,966 m) runway elevation causes planes to land at higher speeds
6,300' (1,920 m) runway length is relatively short for higher speeds and larger aircraft
Accommodates both smaller planes and larger planes like 757's and A320's
8/3/2011
Jackson Hole Air Port - Jackson, WY 5/09
300" (7.62 m) of snow annually
Snow plowing causes pavement to ravel
Temperatures can swing from –40F (-40C) to 41F (5C) in the winter months, and annually from –40F (-40C) winter to104F (40C) summer
8/3/2011
57
8/3/2011
Jackson Hole Air Port - Jackson, WY 5/09
Asphalt plant: Rate averaged 230 tons per hour, (TPH)
Built in 1956, transported to site
Fiber added at discharge shoot, (not recommended)
8/3/2011
Jackson Hole Air Port - Jackson, WY 5/09
Observations: Very good distribution, verified by core samples
1 small fiber clump found in 9,500 tons of asphalt
8/3/2011
58
Laboratory Evaluation in Progress – ACRP
Mix PropertyJAC
Mixture
SHR
Mixture
(Control)
Sieve
Size (US)
Sieve
Size
(SI)
JAC
Mixture
% Passing
SHR
Mixture
% Passing
FAA P-402
Control Points
Gradation Open Open 1" 25.4 - - -
Binder PG 64-34 PG 64-34 3/4" 19 100 100 100
Asphalt Content 5.70% 5.60% 1/2" 12.7 82 85 70-90
Laboratory Target Air
Voids13,15%* 15,17%* 3/8" 9.5 57 52 40-65
Gmm 2.416 2.540 No. 4 4.76 22 19 15-25
Hydrated Lime (%) 0.75% - No. 8 2.38 12 13 8-15
Fiber Reinforcement1 lb/ton
(0.5 kg/MT)None No. 30 0.6 6 7 5-9
Mixing/Compaction
Temp, °F (°C)
325/300
(163/149)
325/300
(163/149)No. 200 0.074 2 2.5 1-5
*Air voids for cylinder and beam samples, respectively (Corelok Method)
Jackson Hole Airport - Why specify FRAC?•Temperature changes from: -40
oF to 41
oF (winter) & up to 104
oF in the summer
•Elevation requires higher approach speeds
•Short runway length
•Accommodates planes such as the 757 and A320
•Snow plowing caused raveling in existing pavement
Field Stresses - Lab Confinement Issues
8/3/2011
59
Dynamic Modulus
Notes: Jackson Hole Airport Mixture – with fibers
Control mixture – without fibers
Confining pressure – 20 psi
10 Hz – represents aircraft on runway
1 Hz – represents aircraft on taxiway
Indirect Tensile Strength
8/3/2011
60
Raveling Test
Location Replicate Wi Wf % Loss Average CV
Jackson Hole Airport
1 986.8 959.6 2.8%
2.6% 16.9%2 970.1 940.2 3.1%
3 967.6 945.1 2.3%
4 1031.5 1009.7 2.1%
Control
1 987.8 953.4 3.5%
3.7% 33.3%2 998.9 971.9 2.7%
3 963.5 910.9 5.5%
4 999.3 968.4 3.1%
•Cantabro Test
•LA abrasion machine without steel balls
•Mashall specimen size
•Test temperature = 25°C
•Recommend a lower test temperature for soft binders
Fatigue Testing
• Four point bending beam test
• Similar performance at 70°F observed
• Initial stiffness = 2800 Mpa (407 ksi)
Beam fatigue comparison at 40°F
8/3/2011
61
CO2 EQUIVALENT EMMISSION COMPARISON
Service life
(Y)
Total kg Annual CO2 Eq. /
km runway (lb/mi runway) % Change
10 128279 (455,703) 100.0%
15 85519 (303,801) 33.3%
20* 64139 (227,850) 0.0%
25 51312 (182,283) -20.0%
30 42760 (151,902) -33.3%
The transport distance was assumed to be 25 km (15.5 miles), the density of
asphalt concrete was taken as 2275 kg/m3 (142 lb/ft3) and a runway width of 45.7 m
(150 feet). The use of FRAC as the FAA P-401 surface course can result in a 33%
decrease in total kg of annual CO2 equivalent per km of runway. This is based on the
assumption that the dynamic modulus increases by 50% to 300,000 psi (1,723) for
FRAC and is also limited by the current FAA design procedures.
* Standard FAA design life
Item
Jackson Hole Airport Sheridan County Airport
Unit $/unit Total Cost Unit $/unit
Total
Cost
P-402 Porous Friction Course,
tons 8530 48.5 $413,705 5800 58.6 $339,880
PG 64-34 Modified Binder, tons 640 1000 $640,000 520 890 $462,800
Total Cost of HMA Mixture
$1,053,70
5 $802,680
Cost per Ton of HMA Mixture $124 $138
Item
Jackson Hole Airport Sheridan County Airport
Unit $/unit Total Cost Unit $/unit
Total
Cost
P-402 Porous Friction Course,
tons 8530 50 $426,500 5800 60.4 $350,320
PG 64-34 Modified Binder, tons 640 1000 $640,000 520 890 $462,800
Fiber Reinforcement Additive,
lbs 8530 7 $59,710 5800 8.35 $48,430
Total Cost of FRAC Mixture
$1,126,21
0 $861,550
Cost Per Ton of FRAC Mixture $132 $149
Cost Comparison
8/3/2011
62
$0
$50,000
$100,000
$150,000
$200,000
$250,000
$300,000
4 6 8 10 12 14 16
Equ
ival
en
t Un
ifo
rm A
nn
ual
Co
st
Service Life (Years)
Jackson Hole
Jackson Hole with Fibers
Sheridan Co
Sheridan Co with Fibers
Cost Comparison
8/3/2011
63
0
250
500
750
1000
1250
1500
1750
2000
2250
2500
2750
3000
3250
Control 1 lb /Ton 2 lb /Ton 3 lb /Ton
Ten
sile
str
engt
h
Mixture Tensile Strength at 40 F
0
250
500
750
1000
1250
1500
1750
2000
2250
2500
2750
3000
3250
Control 1 lb /Ton 2 lb /Ton 3 lb /Ton
Tota
l En
ergy
Mixture Total Energy at 40 F
8/3/2011
64
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65
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67
8/3/2011
68
