mechanistic-empirical pavement design guide … · kamil e. kaloush phd, p.e. associate professor ....
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Kamil E. Kaloush PhD, P.E.Associate Professor
September 15th 2009
Mechanistic-Empirical Pavement Design Guide Implementation and Pavement
Preservation Strategies with A-R
“Cut Cost with Asphalt-Rubber” Seminar Columbus, OH
AgendaMEPDGConventional Versus Asphalt Rubber Mixturesmaterial properties input and implementation requirements into the MEPDG issues for short term implementation recommendations for future / long term implementation
ARFC benefits as a pavement preservation strategy
Mechanistic-Empirical Pavement Design Guide-MEPDG
Based on Mechanistic-Empirical principals.Relates pavement material characteristics with their
performance in the field.Calibrated based on data from the LTPP Project.Capability to adapt to local conditions Special emphasis in the design of rehabilitated
pavements
Hierarchical Design Inputs in the MEPDG
Level 1: Accurate data from laboratory testingLevel 2: Intermediate level of accuracy. Inputs
estimated through correlations Level 3: Lowest level of accuracy. Default
values provided by the program
Input for the Asphalt Concrete Layera. Asphalt General – mix volumetricsb. Asphalt Binder – consistency tests /
AC/PG gradeASTM Ai-VTSi
c. Mix Stiffness – Dynamic Modulus
8628.4)sin
1(10
*
G
))log(393532.0)log(313351.0603313.0(34
238384
42
200200
1005470.0)(000017.0003958.00021.0871977.3
802208.0058097.0
002841.0)(001767.002932.0750063.3*log
f
aeff
effa
e
VVV
V
E
MEPDG Outputa. Permanent Deformationb. Cracking: Transverse, Longitudinal, Fatiguec. Thermal Crackingd. Roughness, IRI
Asphalt Rubber Mixtures
ADOT uses AR mixes for new and rehabilitated pavements.
In 1999, ADOT and ASU joint research program: several AR mixes and binders have been characterized, and some are currently being tested at ASU.
Goal of implementing AR in the MEPDG
To date, over 20 projects included AR mixtures that were tested.
1
35
4
2
6
7
8
9
10
11
ASTM D8Standard Definitions of Terms Relating to Materials for Standard Definitions of Terms Relating to Materials for
Roads and PavementsRoads and Pavements
Asphalt Rubber– a blend of asphalt cement, reclaimed tire rubber and certain additives in which the rubber component is at least 15% by weight of the total blend and has reacted in the hot asphalt cement sufficiently to cause swelling of the rubber particles.
Interacted Rubber 1-2 mm Particles
Existing or new HMA Base Mix
AR Bitumen 6.8- 8%Air Voids 7 - 10%
AR Bitumen Content 8.8 - 10%Air Voids 18 - 20%
Typical HMA Cross Section
ARFC13 mm
ARAC
50 mm ARAC
OpenGap /
SMA
Dense
Base Asphalts for AR Use
Type 1: Hot Climate PG 64-16 Type 2: Moderate Climate PG 58-22 Type 3: Cold Climate PG 52-28
Asphalt Rubber Modified Binder
0
0.2
0.4
0.6
0.8
1
1.2
2.7 2.75 2.8 2.85 2.9 2.95
Log-Temperature (Rankine)
Log
log-
Visc
osity
(cP)
I-17 Project AR 58-22I-17 Project AR PG 64-16I-17 Project PG 58-22I-17 Project PG 64-16ADOT Virgin PG 76-16
Two Original and modified AR binders (at RTFO):PG 58-22PG 58-22ARPG 64-16 PG 64-16 AR
A and VTS
Permanent Deformation - Initial Findings
ARFC (in) ARAC (in) Conventional (in)
Sub total AC (in)
Sub total Base-
Subgrade (in)
Total Rutting (in)
1 0.09 0.25 0.03 0.37 0.27 0.642 0.11 0.33 0.04 0.48 0.3 0.783 0.15 0.44 0.05 0.64 0.32 0.954 0.18 0.51 0.06 0.75 0.33 1.085 0.21 0.59 0.07 0.86 0.34 1.216 0.23 0.67 0.08 0.97 0.35 1.327 0.25 0.72 0.08 1.05 0.35 1.48 0.27 0.77 0.09 1.12 0.36 1.489 0.28 0.81 0.09 1.18 0.36 1.55
10 0.29 0.85 0.1 1.24 0.37 1.6
Buffalo Range Project - Unconfined E* -Default MEPDG Rutting Coefficients
Year
Rutting (in)
0.00
0.50
1.00
1.50
2.00
0 2 4 6 8 10 12Pavement Age (years)
Rut
ting
(in)
Total AC Rutting Total Rutting
Field
Field Stresses - Lab Confinement Issues
Mixtures CharacteristicsTemp (oF)
Freq (Hz)
Dynamic Modulus (ksi) Conventional ARAC ARFC
Unconfined Confined Unconfined Confined Unconfined Confined 14 25 5464 5131 3850 4710 2166 2763
10 5079 4782 3654 4566 2079 2612 5 4803 4504 3466 4374 1956 2456 1 4260 3954 3059 3779 1668 2103
0.5 4046 3708 2890 3520 1548 1950 0.1 3508 3101 2468 2963 1294 1621
40 25 3287 3518 2684 3842 1353 1779 10 3016 3136 2522 3553 1246 1612 5 2815 2895 2354 3266 1133 1463 1 2336 2344 1971 2635 908 1149
0.5 2142 2120 1810 2365 817 1030 0.1 1722 1687 1460 1821 625 781
70 25 2190 2152 1563 2182 751 1030 10 1902 1892 1362 1932 645 915 5 1679 1682 1205 1688 557 799 1 1260 1277 890 1212 386 559
0.5 1091 1128 770 1038 325 480 0.1 769 837 532 714 223 338
100 25 730 715 511 881 297 602 10 578 615 397 715 238 544 5 493 558 324 598 196 484 1 335 404 210 379 132 351
0.5 284 356 173 312 112 310 0.1 200 272 114 217 81 250
130 25 321 339 215 574 197 534 10 254 297 163 470 153 451 5 219 266 133 370 127 385 1 157 204 90 242 87 292
0.5 138 199 78 210 76 260 0.1 104 167 59 168 59 223
130 25 321 339 215 574 197 534 10 254 297 163 470 153 451 5 219 266 133 370 127 385 1 157 204 90 242 87 292
0.5 138 199 78 210 76 260 0.1 104 167 59 168 59 223
Temp (oF)
Freq (Hz)
Dynamic Modulus (ksi) Conventional ARAC ARFC
Unconfined Confined Unconfined Confined Unconfined Confined
E* Master Curves
10,000
100,000
1,000,000
10,000,000
-8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8
Log Reduced Time (sec)
E*
(psi
)
I40 BR ARAC-10 psi I40 BR ARAC-20 psi I40 BR ARAC-30-psi I40 BR ARAC 0psi
10,000
100,000
1,000,000
10,000,000
-8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8
Log Reduced Time (sec)
E*
(psi)
ARFC-Unconfined Confined 10 psi Confined-20 psi Confined-30 psi
ARAC
ARFC
Level 3 Issues – E* Predictive Equation
WE* not calibrated for AR mixes.
))log(393532.0)log(313351.0603313.0(34
238384
42
200200
1005470.0)(000017.0003958.00021.0871977.3
802208.0058097.0
002841.0)(001767.002932.0750063.3*log
f
aeff
effa
e
VVV
V
E
1.0E+03
1.0E+04
1.0E+05
1.0E+06
1.0E+07
1.0E+03 1.0E+04 1.0E+05 1.0E+06 1.0E+07
Measured E* (psi)
Pred
icte
d E*
(psi
)
Data Point=1494, se/sy=0.97 (arithm), 0.96(log)R2=0.076 (arithm) 0.08(log)
Calibrated WE* Equation for AR Mixes-Unconfined
CURRENT EQUATION
NEW PARAMETERS
COEFFICIENT
INTERCEPT 1 3.750063 0.346064
P200 0.029320 0.720506
P2002 -0.001767 -0.2661
P4 -0.002841 0.068005
VA -0.058097 -0.042026
VBEFF -0.802208 -0.067019
INTERCEPT 2 3.871977 4.87167
P4 -0.002100 0.04564
P38 0.003958 0.036857
P382 0.000017 -0.001059
P34 0.005470 0.00547
KF -0.603313 -0.175293
KV 0.313351 -0.480331
BF -0.3953 -0.741099
LOG SE /SY 0.96 0.23
R2 0.08 0.95
ARITHMETICSE /SY 0.97 0.32
R2 0.08 0.90
1.0E+04
1.0E+05
1.0E+06
1.0E+07
1.0E+04 1.0E+05 1.0E+06 1.0E+07
Measured E* (psi)
Pred
icte
d E*
(psi
)
Data Point=1494, se/sy=0.32 (arithm), 0.23(log)R2=0.90 (arithm), 0.95(log)
Dynamic Modulus E*
Calibrated WE* Equation for AR Mixes-ConfinedNew parameters
4.09180.7084-0.18020.0169-0.0284-0.5883-0.67510.03150.0494-0.00130.00550.2338-0.6026-0.6419
Se/Sy 0.32R2 0.9
Se/Sy 0.4R2 0.84Arithmetic
Kf
Kv
bf
Log
p4
p38
p382
p34
p4
Va
Vbeff
Intercept 2
CoefficientIntercept 1
p200
p2002
1.0E+04
1.0E+05
1.0E+06
1.0E+07
1.0E+08
1.0E+04 1.0E+05 1.0E+06 1.0E+07 1.0E+08
Pred
icte
d E*
(psi
)
Measured E* (psi)
Data Point=1260, se/sy=0.399 (arithm), 0.32(log)R2=0.84 (arithm) 0.90(log)
What about the binders?
No PG Grading For AR Mixes included in the MEPDG
Alternative:find the PG grading that best match the Ai and VTSi values for asphalt rubber binders.
Binder Type Ai VTSi
PG 58-22 AR 8.543 -2.781PG 64-40 8.524 -2.798
PG 64 -16 AR 8.048 -2.598PG 70-40 8.129 -2.648
Other MEPDG Issues
• Limitation of the current version of the MEPDG:– Minimum thickness
ARFC 0.5"ARAC 2"
Conventional
Aggregate Base
Subgrade
Other MEPDG Issues– Multiple layers of
mixtures that were not included in calibration;
– Need to re-calibrate
ARFC 0.5"ARAC 2"
Conventional
Aggregate Base
Subgrade
39937.0734.115552.310 NTr
p
Alternative MEPDG RunsDefault or Specific Layer MEPDG rutting
coefficients and E* unconfined / Confined results.
332211
rr aar
r
p NTa
r1 = 0.509r2 = 0.90r3 = 1.2
ARFC 0.5"ARAC 2"
Conventional
Aggregate Base
Subgrade
r1 r2 r3
r1 r2 r3
Permanent Deformation – Case Study
Constructed in 2001(I-40, MP=225)
Asphalt binder and asphalt mix data from laboratory test results (Level 1)
MR =25,000 psi
AADTT =15,000
Design life period =10 years.
Description of the project ARFC 1", AC=8.8%, Va=18%
ARAC 1.5", AC=6.8%, Va=11%
Conventional 4", AC=4.8%, Va=7%
Aggregate Base 8"
Subgrade
Selected Material 12"
Permanent Deformation Results
ARFC (in) ARAC (in) Conventional (in)
Sub total AC (in)
Sub total Base-
Subgrade (in)
Total Rutting (in)
1 0 0.04 0.04 0.09 0.24 0.332 0 0.06 0.06 0.12 0.26 0.383 0 0.08 0.08 0.15 0.28 0.434 0 0.09 0.09 0.18 0.29 0.475 0 0.1 0.1 0.21 0.3 0.516 0 0.12 0.12 0.23 0.31 0.547 0 0.12 0.13 0.25 0.31 0.568 0 0.13 0.13 0.27 0.31 0.589 0 0.14 0.14 0.28 0.32 0.6
10 0 0.15 0.15 0.3 0.32 0.62
Buffalo Range Project -Confined E*- Default MEPDG Rutting Coefficients
Year
Rutting (in) Default MEPDG rutting coefficients and the E* confined results:- AC rutting drastically reduced to 0.3”. - All runs over predicts rutting, but this approach gives the best prediction.
0.00
0.20
0.40
0.60
0.80
0 2 4 6 8 10 12Pavement Age (years)
Rutti
ng (i
n)
Total AC Rutting Total Rutting
Field
0.00
0.50
1.00
1.50
2.00
0 2 4 6 8 10 12Pavement Age (years)
Rut
ting
(in)
Total AC Rutting Total Rutting
Field
Fatigue Cracking Model
32
32
)()(1111
kkt
kk
tf Ek
EkN
Min Max k1 1.20E-08 7.50E-01 k2 4.2 8.2 k3 1.3 2.6 k1 3.00E-05 8.00E+03 k2 3 6.7 k3 1.5 2.7 k1
k2
k3
Regression Coefficients k1, k2, k3
ARAC
ARFC
MEPDG7.60E-03
3.951.28
Evaluation of Fatigue Cracking
7 years field distress survey: fatigue cracking approximately 7%. Use of confined E* and specific ARAC coefficients seems to help in better predicting of fatigue cracking.
1 0.48 0.44 0.47 0.442 3.53 3.04 3.31 3.033 12.4 9.75 11.21 9.734 20.29 13.2 17.07 13.145 26.31 13.94 20.71 13.826 31.97 14.05 24.00 13.887 37.60 14.17 27.42 13.958 42.92 14.30 30.83 14.019 47.74 14.43 34.14 14.0810 52.03 14.55 37.30 14.14
Total Cracking at Surface (%)
YearUnconfined-
Default Coefficients
Unconfined-ARAC
Coefficients
Confined-Default
Coefficients
Confined-ARAC
Coefficients
AR binders had improved viscosity-temperature susceptibility. Crumb rubber bumps up the PG by at least one level.
AR Binder: find PG that best match the Ai and VTSi values.
Unconfined / Confined E* tests: effect of confinement on moduli values more pronounced for AR mixtures.
Level 1: Must use confined E* test results / Master Curves.
Level 3: use modified WE* equation; if nothing else, use it to genereae dynamic modulus input data for Level 1 analysis.
Minimum AC layer thickness: use 1 in thick layer for ARFC and subtract difference from others; or completely ignore ARFC layer.
Concluding Remarks – Input MEPDG Data
Concluding Remarks – MEPDG Output
For Permanent Deformation / Rutting model: use existing model and confined E* >> best predictions.
Consider a recalibration on the AC Rutting Model based on all mixtures (Conventional, ARAC, and ARFC) until future MEPDG versions allows entering different set of calibration coefficients.
Confined E* and specific ARAC coefficients provide better prediction of fatigue cracking.
For future fatigue cracking analysis, run the MEPDG with the calibrated fatigue coefficients that are specific to the AC layer where fatigue cracking will initiate.
Is ARFC a Good Pavement Preservation Strategy?
1. Performance2. Friction / Safety3. Ride Quality / Comfort 4. Thermal Gradient / Urban Climate Interaction5. Highway Noise6. Tire Wear Emissions / Air Quality7. Life Cycle Cost8. Energy Consideration
Asphalt Rubber Friction Course – 20 to 25 mm
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
Years
AR
HMA
Percent Cracking
HMA
AR
I-10 TEST SECTIONS
AR-ACFC ¾”
SMA ¾”P-ACFC ¾”
PEM 1 ¼” ACFC ¾”Field Noise
Validation Studies
Tire / Pavement Noise (dB) for Arizona I-10 Test Sections
102.84
99.94
104.68
101.56102.17
99.8
101.0100.6
99.8
98.9
96
97
98
99
100
101
102
103
104
105
106
AR-ACFC ACFC P-ACFC PEM SMA
Tir
e / P
avem
ent N
oise
(dB
)
Dynatest 2008 at 100 Km/h Scofield-Donovan 2002 at 100 Km/h
Friction / SafetyAverage Friction Value LANE PCCP AR-ACFC I010EHOV 0.54 0.66 I010ELN1 0.60 0.61 I010ELN2 0.49 0.61 I010ELN3 0.47 0.60 I010ELN4 0.47 0.54
I010WHOV 0.51 0.58 I010WLN1 0.64 0.57 I010WLN2 0.50 0.59 I010WLN3 0.44 0.59 I010WLN4 0.42 0.58
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
50 250 450 650 850 1050 1250 1450 1650 1850 2050 2250 2450 2650
Fric
tion
Valu
e (M
u)
Friction average every 50 feet
Friction Test-Deck Park Tunnel I010 East HOV Lane @ 60 mph Comparison PCCP to AR-ACFC
PCCP
AR-ACFC
Profilometer Test-Deck Park Tunnel I010 East HOV Comparison PCCP to AR
102030405060708090
100110120130140150160170
100
200
300
400
500
600
700
800
900
1000
1100
1200
1300
1400
1500
1600
1700
1800
1900
2000
2100
2200
2300
2400
2500
2600
2700
Distance every 100ft
IRI(I
N/M
I)
PCCPA R
Ride Quality / RoughnessIRI (in/mi) LANE PCCP AR-ACFC
I010EHOV 96.34 43.57 I010ELN1 123.20 59.03 I010ELN2 104.29 48.81 I010ELN3 111.87 47.80 I010ELN4 115.30 52.91
I010WHOV 85.44 32.51 I010WLN1 87.94 37.79 I010WLN2 85.40 46.92 I010WLN3 96.83 46.11 I010WLN4 97.75 36.81
Field Investigation of PCC Thermal BehaviorTemperature
Gradients induce damaging Curling Stresses
Courtesy AZ511.com
Thermal Gradient Test Site
Thermal Gradients EffectThermal Blanket Effect
of ARFC reduces PCC Curling Stresses (8- 25%)
Observed benefits of porosity and lower thermal mass of the ARFC layer.
Urban Heat Island
Air Quality
Rare opportunity to sample tire wear emissions at the tunnel before and after the AR-ACFC overlay.
Deck Park Tunnel, I-10 Phoenix, AZ
Based on Tire Wear Tracers
Tire Wear Emission Rates
Emission rates calculated per kilometer driven (g/km).
Tire wear emission rate based on
Experiment 1 (PCC road surface)
Experiment 2 (AR-ACFC road surface)
Compound # 3 354 ± 71 177 ± 35 Compound # 4 172 ± 34 120 ± 24
May 2004 and June 2005
Cost BenefitsLonger Service LifeReduced cracking and maintenance.Reduced thickness.
0100200300400500600700800900
100011001200
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Year
Mai
nten
ance
Cos
t $/la
ne-K
m
Overlays / Inlays
AR-ACFC
Process kJ/kgTire Shedding -1744
Shred Transportation -1744
Granulation -3586CRM
Transportation -1744Steel Recovery 1900Asphalt Saved 209,325 to 465,168
Aggregate Saved 107,860Gain / Loss 310,267 to 566,109
½ Thickness Design Criteria
Energy Consideration
0
5,000
10,000
15,000
20,000
25,000
Production kg An. CO2 Eq. / km Mixing kg An. CO2 Eq. / km Transportation kg An. CO2 Eq. / km
Transportation kg An. CO2 Eq. / km 2,670 2,823 3,722
Mixing kg An. CO2 Eq. / km 6,834 4,124 11,210
Production kg An. CO2 Eq. / km 3,319 8,060 4,517
AR 2.5" over Base 6" UTW 2" over Base 6" HMA 4" over Base 6"
Positive Impact on CO2 Emissions
Conclusions• ARFC is a Pavement Preservation Strategy because:
– Performance / Durability √
– Safety √
– Ride Quality √
– Quality of Life Issues √• Highway Noise• Air Quality• Urban Heat Island
– Cost Effective
– Positive Impact on Energy / CO2 emmisions√
Arizona
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