Understanding the Understanding the Performance of Modified Performance of Modified
Asphalts in MixturesAsphalts in MixturesNCHRP 90NCHRP 90--07, TPF 5(019)07, TPF 5(019)
Thomas HarmanThomas HarmanMaterials & Construction Team Leader, R&DMaterials & Construction Team Leader, R&D
Federal Highway AdministrationFederal Highway Administrationwww.TFHRC.govwww.TFHRC.gov
United StatesUnited StatesNNational ational HHighway ighway SSystemystem
•• A A $1 trillion$1 trillion investment/priceless investment/priceless national assetnational asset
•• The way nearly all products moveThe way nearly all products move
•• InterInter--modal link to seamodal link to sea→→air air →→railrail
•• Permits our high quality of life & Permits our high quality of life & economic growtheconomic growth
•• NHS is over 160,000 miles of pavementNHS is over 160,000 miles of pavement
–– most over 35 years old most over 35 years old
–– $59 billion shortfall to maintain condition$59 billion shortfall to maintain condition
•• SafetySafety tied to pavement conditiontied to pavement condition
•• Customer/User expectations Customer/User expectations
–– Safer pavementsSafer pavements
–– Smoother rideSmoother ride
–– Quieter pavementsQuieter pavements
–– Reduced delay & congestionReduced delay & congestion
United StatesUnited StatesNNational ational HHighway ighway SSystemystem
Annual HMA InvestmentAnnual HMA Investment
•• $15 Billion$15 Billion
•• 500 M tons of HMA500 M tons of HMA
•• 30 M tons of binder30 M tons of binder
Up 400%
Up 32%
Up 63%
Up 90%
Up 132%
Up 6%
Traffic congestion Traffic congestion on the rise!on the rise!
Compared with Compared with 1970:1970:
MilesTraveled
1970
Americans Drivers Vehicles Ton Miles Highways
Cost ofCongestion
Hrs / Day When Roads
are Congested
Driver Time Lost in Rush
Hour
Following Following current current
congestion congestion trends:trends:
More than 8 hours per day!
About 80 hours per year!
More than $250 per year per American!
Extra Vehicle Operating Cost per YearExtra Vehicle Operating Cost per YearDue to Due to PoorPoor Pavement ConditionPavement Condition
$ 41.5 Billion / year !$ 41.5 Billion / year !
$222
$432
$23
$0$50
$100$150$200$250$300$350$400$450$500
AVERAGE HIGH LOW
The Road Information Program (TRIP)April 2001
STATEAverages
But Things are ImprovingBut Things are Improving
•• 2002 Report on Conditions and 2002 Report on Conditions and Performance of the NHSPerformance of the NHS–– 86.0% with acceptable ride quality86.0% with acceptable ride quality–– Up from 82.5% in 1993Up from 82.5% in 1993–– A trend reversalA trend reversal–– Most of the improvement on higher order Most of the improvement on higher order
highwayshighways–– What we are doing What we are doing –– we are doing better!we are doing better!
Materials
Structural
Construction
Get In
Stay In
Get Out
Stay Out
OutlineOutline
•• Superpave® Binder ETG DirectionSuperpave® Binder ETG Direction•• Preliminary FHWA ALF ResultsPreliminary FHWA ALF Results•• Next StepsNext Steps
•• Goal Goal -- Right materialsRight materialsprovide the best provide the best performance!performance!
PAVPAV -- aging aging
RTFORTFO -- aging aging NoNo agingaging
TimeTime
RVRV DSRDSR BBRBBR
DTTDTT
Rutting Fatigue Cracking Thermal CrackingProduction Rutting Fatigue Cracking Thermal Cracking
SuperpaveSuperpave®® Binder SpecificationBinder SpecificationRutting, Fatigue, and LowRutting, Fatigue, and Low--Temp. CrackingTemp. Cracking
WHEN WHAT HOW WHERE
Construction Safety
PumpabilityRutting
Flash PointRot Visc G* / sin δ
230 min 3 Pa-s max
T(high)
Early (RTFO) Rutting G* / sin δ T(high)
Late (+PAV)
Fatigue Low Temp
G* sin δ BBR/DTT
T(inter) TCR
SuperpaveSuperpave® ® 20022002•• Asphalt Binder Implementation StatusAsphalt Binder Implementation Status
Implemented
In Progress
Undetermined
Implemented
In Progress
Undetermined
SuperpaveSuperpave®® PlusPlus•• Elastic recoveryElastic recovery•• Forced ductilityForced ductility•• Toughness and tenacityToughness and tenacity•• Phase anglePhase angle•• Method Method
(mode and dose)(mode and dose)•• CombinationsCombinations
0
10
20
30
40
50
As is Modified
PG Grade Specifications
Num
ber
of S
tate
s14
SuperpaveSuperpave® ® Performance GradingPerformance Grading
High Pav. Temp.50% Reliability
PG 70PG 64PG 58PG 52PG 46PG 40PG <34
PG 58→
←PG 58
Adjusting Model for PerformanceAdjusting Model for Performance“Degree Days”“Degree Days”
Frequency and Damage vs. Temperature
0
2000
4000
6000
8000
10000
12000
11 15 19 23 27 31 35 39 43 47 51 55 59 63 67 71
Pavement Temperature, C
Freq
uenc
y, H
ours
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
Dam
age
FrequencyDamage
SuperpaveSuperpave®® Binder SpecificationBinder SpecificationShort Term Aging Short Term Aging -- NCHRPNCHRP
?
SuperpaveSuperpave®® Binder SpecificationBinder SpecificationRuttingRutting
?
G* / sin δ
1
Shear Stress, kPa
10 20
1
Shear Stain, mm/mm
10 20
SuperpaveSuperpave®® Binder SpecificationBinder SpecificationFatigueFatigue
?
G* sin δ
StressStress
StrainStrain
ττmaxmax
γγmaxmax
Little ResearchUsing
Microwave Technology
SuperpaveSuperpave®® Binder SpecificationBinder SpecificationLong Term AgingLong Term Aging
?
SuperpaveSuperpave®® Binder SpecificationBinder SpecificationLow Temperature Cracking (Thermal Fatigue)Low Temperature Cracking (Thermal Fatigue)
?
R&D
SuperpaveSuperpave®® IIIIPG based on Degree DaysPG based on Degree Days
WHEN WHAT HOW WHERE
Construction Safety
PumpabilityRutting
Flash PointRot Visc f’ (G* δ)
230 min 3 Pa-s max
T(high)
Early (GRF, TX) Rutting f’ (G* δ) T(high)
Late (PAV)
Fatigue Low Temp
f”(G*δ)DT DT ABCD
T(inter) TCR
Output – Validation/Calibration Data, Specification Recommendations
RelationshipsRelationships
TRB Superpave Committee-Binder ETG-Mix/Aggregate ETG
TPF 5(019) / SPR 2(174)Technical Working GroupTWG
LaboratoryStudy 90-07
ALF LoadingResponse Data
CollaborativeResearchers
IndustrySupport
Technical Working Group (TWG) Meeting December 5-6, 2002(17 States, 29 Industry Partners/Collaborative Researchers)
Not YetTPF-5(019)SPR-2(174)
Final Test Matrix… Final Test Matrix…
AZCRM----70-22
1
PG70-22Control
2
AirBlown
3
SBS
4
TXTBCR
5
T-P
6
PG70-22
+Fibers
7
PG70-22
8
SBS64-40
9
AirBlown
10
SBS
11
T-P
12
Mix DesignsMix DesignsFHWA 0.45 Power Chart
12.5 mm Nominal Maximum Size
0.075 0.3 1.18 4.75 9.5 12.5 25192.360
10
20
30
40
50
60
70
80
90
100
Sieve Size, mm
Perc
ent P
assi
ng
Moderate Traffic Mix
FHWA 0.45 Power Chart12.5 mm Nominal Maximum Size
0.075 0.3 1.18 4.75 9.5 12.5 25192.360
10
20
30
40
50
60
70
80
90
100
Sieve Size, mm
Perc
ent P
assi
ng
Superpave12.5mm NMSCoarse GradedPb = 5.3 %PG 74-28Ndes = 75
Arizona CRM12.5mm NMSCoarse GradedPb = 7.1 %PG 58-22 with17% CRM
1 2 3 4 5 6 7 8 9 10 11 12
RuttingTest
FatigueTest
LaneALF Testing StatusALF Testing Status
*Initial Strain Measurements: 100% Complete*Rutting Tests: Shakedown Tests Complete (5, 9)*Rutting Tests: 5 of 12 Lanes Complete*Fatigue Tests: Shakedown Test Complete (1)
Completed Test Shakedown Test
ALF ALF -- LaboratoryLaboratory
Preliminary ResultsPreliminary Results
FHWA ALF
0
5
10
15
20
25
0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000ALF Passes, 45kN (10kip) at 64C
Rut
Dep
th, m
mTBCR 79-28SBS 64-40 / 71-38SBS 64-40 / 71-38Air Blown 74-28Ter-Polymer 74-31Control 72-23AZ CRM
12.7 11.88.8
100mm
15.7 15.7
19.5
0.0
5.0
10.0
15.0
20.0
ALF
Rut
ting
afte
r 40,
000
Pass
es a
t 64°
C, (
mm
)
AZ CR E-T TBCR PG 70-22 Air Blown SBS 64-40
Asphalt Binder
Prelim inary ALF Results
FHWA ALF
SBS 64-40: y = 0.3037x - 1.513, R2 = 0.98
TBCR: y = 0.1529x - 1.1525, R2 = 0.98
T-Polymer: y = 0.157x - 1.0456, R2 = 1.00
AZ CR: y = 0.1695x - 1.0816, R2 = 0.99Control: y = 0.1794x - 1.0318, R2 = 0.99
SBS 64-40: y = 0.2927x - 1.4978, R2 = 0.98Air Blown: y = 0.2366x - 1.3018, R2 = 0.99
-0.800
-0.700
-0.600
-0.500
-0.400
-0.300
-0.200
-0.100
0.0000 1 2 3 4 5 6
LOG (ALF Passess - 45kN(10 kips) at 64°C)
LOG
(Rut
ting
with
in A
C la
yer,
in) TBCR
SBS 64-40SBS 64-40Air BlownT-PolymerControlAZ CRLinear (SBS 64-40)Linear (TBCR)Linear (T-Polymer)Linear (AZ CR)Linear (Control)Linear (SBS 64-40)Linear (Air Blown)
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
Slop
e: L
og(R
uttin
g)/L
og(P
asse
s)
TBCR SBS 64-40 SBS 64-40 Air Blown T-Polymer Control AZ CR
FHWA ALF
71-38 74-28 74-31 72-2379-28
Preliminary ALF Data
AB
PG 70-22
TB CR
SBS 64-40E-T
AZ CR
R2 = 0.17
0.0
5.0
10.0
15.0
20.0
25.0
0.0 5.0 10.0 15.0 20.0 25.0
ALF Rut Depth at 40,000 Passes, 64°C
Fren
ch P
RT,
Rut
Dep
th a
t 60
,000
/ 74
°C, m
m
Preliminary ALF Data
SBS 64-40
E-TPG 70-22
ABTBCR
AZ CR
R2 = 0.23
0
2,000
4,000
6,000
8,000
10,000
12,000
14,000
16,000
0.0 5.0 10.0 15.0 20.0 25.0
ALF Rut Depth at 40,000 Passes, 64°C
Ham
burg
, Whe
el P
asse
s to
20
mm
at 6
4°C
Preliminary ALF Data
PG 70-22AB
SBS 64-40E-T
TBCR
AZ CR
R2 = 0.76
20,000
25,000
30,000
35,000
40,000
45,000
50,000
55,000
60,000
0.0 5.0 10.0 15.0 20.0 25.0
ALF Rut Depth at 40,000 Passes, 64°C
RSC
H, G
* at 1
0 H
z / 7
4°C
, MPa
Preliminary ALF Results
SBS 64-40PG 70-22
AB
TB CR
AZ CR
AZ CR
R2 = 0.86
0
500
1,000
1,500
2,000
2,500
0.0 5.0 10.0 15.0 20.0 25.0
ALF Rut Depth at 40,000 Passes, 64°C
RSC
H C
ycle
s to
2%
CPS
S,
74°C
SignificanceSignificance
•• Superpave Shear TesterSuperpave Shear TesterRepeated Shear at Constant Height toRepeated Shear at Constant Height to2% Cumulative Permanent Shear Strain2% Cumulative Permanent Shear StrainTracks ALF Rutting PerformanceTracks ALF Rutting Performance
Preliminary ALF Results
ABPG 70-22
TB CR
E-T
AZ CR
AZ CR
R2 = 0.86
0
500
1,000
1,500
2,000
2,500
0.0 5.0 10.0 15.0 20.0 25.0
ALF Rut Depth at 40,000 Passes, 64°C
RSC
H C
ycle
s to
2%
CPS
S, 7
4°C
Superpave Performance TestsSuperpave Performance Tests
•• Dynamic Modulus, |E*|Dynamic Modulus, |E*|•• Flow TimeFlow Time•• Flow Number Flow Number –– Repeated CreepRepeated Creep
•• Ongoing Testing…Ongoing Testing…
Binder Specification Binder Specification ParametersParameters
Preliminary ResultsPreliminary Results
High Temperature High Temperature ParametersParameters
•• |G*|/sin δ|G*|/sin δ @@10 radians 10 radians (Superpave)(Superpave)
•• |G*|/(1|G*|/(1--(1/tanδ (1/tanδ sinδsinδ)))) @@0.25 radians 0.25 radians (Shenoy)(Shenoy)
•• % % γγaccacc Repeated Creep Repeated Creep @@ 300 Pa 300 Pa ((BahiaBahia))
•• η’η’ @@ 0.01 radians/s, LSV 0.01 radians/s, LSV ((DongreDongre’/D’Angelo)’/D’Angelo)
•• ηη00 @@ ~0 radians/s, ZSV ~0 radians/s, ZSV (Rowe)(Rowe)
•• MVRMVR, 1.225kg load, cc/10min , 1.225kg load, cc/10min ((ShenoyShenoy))
High Spec. Temperature, THigh Spec. Temperature, THSHS
•• |G*|/sin δ = 2200 Pa|G*|/sin δ = 2200 Pa (Superpave)(Superpave)
•• |G*|/(1|G*|/(1--(1/tanδ (1/tanδ sinδsinδ)) = 50 Pa)) = 50 Pa (Shenoy)(Shenoy)
•• % % γγaccacc No CriterionNo Criterion ((BahiaBahia))
•• η’ = 250 Paη’ = 250 Pa--ss, LSV , LSV ((DongreDongre’/D’Angelo)’/D’Angelo)
•• ηη00 = 250 Pa= 250 Pa--ss, ZSV , ZSV (Rowe)(Rowe)
•• MRV = 50 cc/10min MRV = 50 cc/10min ((ShenoyShenoy))
HighHigh--Temperature PerformanceTemperature PerformanceII--80, Nevada80, Nevada
Same gradation Same gradation -- different binders.different binders.
PG 63-22 modified No rutting
PG 67-22 unmodified 15mm of rutting
High Temperature (Rutting)High Temperature (Rutting)Repeated Creep Recovery TestRepeated Creep Recovery Test
0
2000
4000
6000
8000
10000
12000
0 200 400 600 800 1000 1200
Time, (seconds)
Stra
in, (
%)
PG 63-22 Modified
PG 67-22 Neat AC
Repeated Creep Test ResultsRepeated Creep Test ResultsTwo binders of Same PGTwo binders of Same PG--Grade Grade
4.80
4.90
5.00
5.10
5.20
5.30
5.40
5.50
487 492 497 502 507 512
Time (s)
Stra
in (m
m/m
m)
B 6281 (PG74-28)
B 6289 (PG74-31) Limited Recovery, ABALF, 15.7mm, s=0.24
Higher recovery, T-PALF, 8.8mm, s=0.15
Repeated Creep Test ResultsRepeated Creep Test ResultsTwo binders of Different PGTwo binders of Different PG--GradesGrades
1.70
1.90
2.10
2.30
2.50
2.70
487 492 497 502 507 512
Time (s)
Stra
in (m
m/m
m)
B 6280 (PG71-38)
B 6286 (PG79-28)
TBCRALF, 8.8mm, s=0.15
SBSALF, 19.5mm, s=0.30
Summary of Findings To DateSummary of Findings To DatePreliminary ResultsPreliminary Results
•• Current specification Current specification does notdoes not adequately adequately identify the benefits of modifiersidentify the benefits of modifiers
•• RSCHRSCH tracks ALF rutting performancetracks ALF rutting performance
•• A wide range of A wide range of high specification high specification temperature parameters are being temperature parameters are being evaluatedevaluated
What’s NextWhat’s Next
•• Fatigue TestingFatigue Testing–– Two TemperaturesTwo Temperatures
•• Rutting TestingRutting Testing–– 7 Lanes7 Lanes
•• Additional SectionsAdditional Sections–– TBDTBD
•• Superpave SPTSuperpave SPT–– |E*|, Creep|E*|, Creep
•• Beam FatigueBeam Fatigue
•• LowLow--Temp StudyTemp Study–– ABCD, DT, TABCD, DT, TCRCR
SuperpaveSuperpave®® II II –– 2005/62005/6PG based on Degree DaysPG based on Degree Days
WHEN WHAT HOW WHERE
Construction Safety
PumpabilityRutting
Flash PointRot Visc f’ (G* δ)
230 min 3 Pa-s max
T(high)
Early (GRF, TX) Rutting f’ (G* δ) T(high)
Late (PAV)
Fatigue Low Temp
f”(G*δ)DT DT ABCD
T(inter) TCR
Binder Specification Binder Specification DirectionDirection
•• To better handle neat asphaltsTo better handle neat asphalts•• To address modifiersTo address modifiers•• To do it faster, To do it faster,
better, and better, and more economical!more economical!
*** RULES ***
TESTS NEED TO BE:
EASY TO SET UP
EASY TO PERFORM
EASY TO ANALYZE
