Revised T.T.S. + Statistical Analysis - engineering.purdue.eduspave/old/Technical Info/Meetings... · 15.0 20.0 0 1000 2000 3000 4000 5000 RSCH Cycles to Failure at 74°C 100mm Pavemen

“Understanding the “Understanding the Performance of Modifiers in Performance of Modifiers in

Asphalt Mixtures” Asphalt Mixtures” ––6767--80 Binder Study80 Binder Study

Revised T.T.S. + Revised T.T.S. + Statistical AnalysisStatistical Analysis

Materials & Construction TeamMaterials & Construction Team

Federal Highway AdministrationFederal Highway Administrationwww.TFHRC.govwww.TFHRC.gov

AcknowledgementsAcknowledgements

Thanks toThanks to•• Mr. Scott Parobeck Mr. Scott Parobeck •• Mr. Frank Davis Mr. Frank Davis •• Ms. Susan Needham Ms. Susan Needham •• Dr. Ghazi AlDr. Ghazi Al--Khateeb Khateeb •• Dr. Aroon Dr. Aroon ShenoyShenoy•• Mr. Nelson GibsonMr. Nelson Gibson

6767--80 Binder Study80 Binder StudyOutlineOutline

•• 6767--80 Binders80 Binders•• Mixture CharacterizationMixture Characterization•• Research ApproachResearch Approach•• Proposed Binder ParametersProposed Binder Parameters•• ResultsResults•• ObservationsObservations

Current Completion DatesCurrent Completion Dates

•• Rutting testing Jan. 2004Rutting testing Jan. 2004•• Fatigue testing (100Fatigue testing (100--mm) Mar. 2006mm) Mar. 2006•• Fatigue testing (150Fatigue testing (150--mm) Dec. 2007mm) Dec. 2007

Two FHWA ALFs with Two FHWA ALFs with 12 Pavement Lanes Constructed in 12 Pavement Lanes Constructed in

the Summer and Fall of 2002the Summer and Fall of 2002

2001 ALF Pavement Facility2001 ALF Pavement FacilityTarget Grade, AB cTarget Grade, AB c--PG 74PG 74--2828

Binder IDBinder ID cc--PG HTPG HT cc--PG LTPG LT UTIUTI

1: AZ CR1: AZ CR2/8: Control2/8: Control3/10: Air3/10: Air--blownblown4/11: SBS4/11: SBS--lglg5: TBCR5: TBCR6/12: Terpolymer6/12: Terpolymer9: SBS 649: SBS 64--4040

n/an/a727274747474797974747171

n/an/a--2323--2828--2828--2828--3131--3838

n/an/a9595102102102102103103105105109109

UTI – Useful Temperature Index

In situ ALF BindersIn situ ALF Binders

-40

-34

-28

-2258 64 70 76 82

Continous High Temperature Grade, (c-HT) °C

c-LT

, °C

ControlAirblownSBS-lgTBCRTerpolySBS

ETG Concern

6767--80 Binders80 Binders

-40

-34

-28

-2258 64 70 76 82 88

Continous High Temperature Grade, (c-HT) °C

c-LT

, °C

EFEF + SBSTerpolyTBCRSBS lg

58 64 70 76 82 88

Mixture Test at HT cMixture Test at HT c--PGPG

•• Superpave Shear Tester (SST)Superpave Shear Tester (SST)–– Repeated Shear at Constant Height (RSCH)Repeated Shear at Constant Height (RSCH)

Cycles to 2% Strain FailureCycles to 2% Strain Failure•• Strain at 5,000 cyclesStrain at 5,000 cycles•• Strain at 1,000 cyclesStrain at 1,000 cycles

Mixture Test at HT cMixture Test at HT c--PGPG

•• Cycles to 2% Strain FailureCycles to 2% Strain Failure•• Best connection to Full Scale Rutting (ALF)Best connection to Full Scale Rutting (ALF)

RD = - 0.004 NRSCH Failure + 19.0

0.0

5.0

10.0

15.0

20.0

0 1000 2000 3000 4000 5000

RSCH Cycles to Failure at 74°C

150m

m Pa

veme

nt Ru

t Dep

th at

64°C

(mm)

RD = - 0.003 NRSCH Failure + 15.8

0.0

5.0

10.0

15.0

20.0

0 1000 2000 3000 4000 5000

RSCH Cycles to Failure at 74°C

100m

m P

avem

ent R

ut D

epth

at

64°C

(mm

)

Outlier = Terpolymer

R2 = 0.77

R2 = 0.99

150mm

100mm

Summary of 67Summary of 67--80 Mixture Testing80 Mixture TestingCV for Trimmed Mean CV for Trimmed Mean (5(5--2=3)2=3)

•• 6% < COV < 45%6% < COV < 45%•• Most ~ 15%Most ~ 15%

Working Data Set after Trimmed Working Data Set after Trimmed Mean AnalysisMean Analysis

•• Typical ExampleTypical Example

0

250

500

750

1000

1250

1500

68 70 72 74 76 78 80 82 84

SST RSCH Test Temperature, °C

Cyc

les

to 2

% S

trai

n

Trimmed Mean Variability

Much care was taken in this experiment, however, results do not always follow expected decreasing trend

– THIS IS A FACT OF LIFE WITH HT SST.

RR22 Approach…Approach…Understanding R2 behavior as linear slope approaches zero for various qualities of data.

0

0.2

0.4

0.6

0.8

1

0.0001 0.001 0.01 0.1 1 10 100 1000

Data Quality = Standard Deviation about Underlying Linear Function

R2

Slope 100

Slope 10

Slope 1

Slope 0.1

RR22 ApproachApproachUnderstanding R2 behavior as linear slope approaches zero for various qualities of data.

0

0.2

0.4

0.6

0.8

1

0.0001 0.001 0.01 0.1 1 10 100 1000

Data Quality = Standard Deviation about Underlying Linear Function

R2

Slope 100

Slope 10

Slope 1

Slope 0.1

Slope 0.000005

Conclusion – R2 is not the most appropriate method. Essentially R2=1 for a perfect horizontal Model, but HYPERSENSITIVE. Smallest deviation from perfect horizontal causes poor R2 with moderate variability.

Pivotal Question…Pivotal Question…

•• Can we perform SST tests at cooler temperature Can we perform SST tests at cooler temperature where variability is smaller ?where variability is smaller ?

•• Then……relate test data to warmer conditions Then……relate test data to warmer conditions where ETG suggests mixture tests be where ETG suggests mixture tests be performed.performed.

•• WHAT TOOLS ARE AVAILABLE TO DO WHAT TOOLS ARE AVAILABLE TO DO SOMETHING LIKE THIS WITH EXISTING DATA ?SOMETHING LIKE THIS WITH EXISTING DATA ?

Pivotal QuestionPivotal Question(NCHRP 9(NCHRP 9--19)19)

•• Utilization of Utilization of TIME TEMPERATURE TIME TEMPERATURE SUPERPOSTIONSUPERPOSTION–– Creep & Permanent Deformation at Multiple Creep & Permanent Deformation at Multiple

Temperatures…Neat 64Temperatures…Neat 64--22 Dense Graded22 Dense Graded–– It is Feasible to “Shift” Permanent Strains like |G*|It is Feasible to “Shift” Permanent Strains like |G*|

-3

-2.5

-2

-1.5

-1

-0.5

0

0 500 1000 1500 2000Reduced Time, sec

Stra

in, %

Shifted 45oC Avg. 3 ReplicatesUnshifted 35oC Avg. 3 Replicates

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

0 1000 2000 3000 4000Reduced Time, sec

Stra

in, %

Shifted 35oC Avg. 3 ReplicatesUnshifted 25oC Avg. 3 Replicates

Calibrate a SST RSCH Model with integrated Calibrate a SST RSCH Model with integrated Time Temperature SuperpositionTime Temperature Superposition

0

500

1000

1500

2000

2500

3000

3500

68 70 72 74 76 78 80 82 84

SST RSCH Test Temperature, oC

# S

ST

RS

CH

Cycle

s to

2%

Pe

rma

ne

nt S

tra

in

High Calib

Measured

( ) ( ) ( ) 213

223

212

23311

23322

22211 666 τττσσσσσσσ +++−+−+−=eq

212

211 3τσσ +=eq

( )( )qvp

peq

R

vp

B

Adtd

12

12

γ

σγ=

From Binder |G*|Trimmed Mean Variability

)(TattR =

Each Binder Parameter for Each Binder Has a Distinct Temperature


0

500

1000

1500

2000

2500

3000

3500

68 70 72 74 76 78 80 82 84


# S

ST

RS

CH

Cycle

s to

2%

Pe

rma

ne

nt S

tra

in

High Calib

Int. Calib

Measured

( ) ( ) ( ) 213

223

212

23311

23322

22211 666 τττσσσσσσσ +++−+−+−=eq

212

211 3τσσ +=eq

( )( )qvp

peq

R

vp

B

Adtd

12

12

γ

σγ=


)(TattR =



0

500

1000

1500

2000

2500

3000

3500

68 70 72 74 76 78 80 82 84


# S

ST

RS

CH

Cycle

s to

2%

Pe

rma

ne

nt S

tra

in

High Calib

Int. Calib

Low Calib

Measured

( ) ( ) ( ) 213

223

212

23311

23322

22211 666 τττσσσσσσσ +++−+−+−=eq

212

211 3τσσ +=eq

( )( )qvp

peq

R

vp

B

Adtd

12

12

γ

σγ=


)(TattR =


High Spec. Temperature, THigh Spec. Temperature, THSHS

•• |G*|/sin |G*|/sin δ = 2200 Paδ = 2200 Pa at 10 rads/sat 10 rads/s (Superpave)(Superpave)

•• |G*|/(1|G*|/(1--(1/tan(1/tanδδ sinsinδ)) = 50 Paδ)) = 50 Pa at 0.25 rads/sat 0.25 rads/sCriterion 1 Criterion 1 (FHWA)(FHWA)

•• TTE E /(1/(1--(1/tan(1/tanδδ sinsinδ)) where Tδ)) where TEE is when |G*|= 50 is when |G*|= 50 PaPa at 0.25 rads/sat 0.25 rads/sCriterion 2 Criterion 2 (FHWA)(FHWA)

High Spec. Temperature, THigh Spec. Temperature, THSHS

•• η’ = 220 Paη’ = 220 Pa--ss, LSV , LSV at 0.01 rads/sat 0.01 rads/s (Binder ETG)(Binder ETG)

•• ηη00 = 250 Pa= 250 Pa--ss, ZSV , ZSV at 0 rads/sat 0 rads/s (Binder ETG)(Binder ETG)

•• MVR MVR = 50 cc/10min= 50 cc/10min at 1.225 kg loadat 1.225 kg load (FHWA)(FHWA)

Results Results -- ExampleExample

SST Test Results Determined Using Time-Temp Superposition at Different Individual Binder Parameter Temperatures

0

0.001

0.002

0.003

0.004

0.005

0.006

0 500 1000 1500 2000 2500 3000

SST RSCH Cycles to 2% Strain

No

ma

l D

istr

ibu

tio

n F

req

ue

nc

y

B6313 CRTB PG70-25B6314 CRTB PG76-25B6315 CRTB PG82-23B6324 SBS-LG PG68-26B6325 SBS-LG PG77-23B6326 SBS-LG PG84-22B6310 TP PG59-30B6312 TP PG72-31B6316 TP PG82-24Effective Combined

|G*|/sin δ

Intermediate SST Calibration

Results Results ––Lower SST CalibrationLower SST Calibration

|G*| sind

|G*| (1-(1/tandsind))

TE (1-(1/tandsind)) ZSV LSV MVR

B6313 CRTB PG70-25 27.6% 5.3% 1.0% 4.8% 4.4% 24.4%B6314 CRTB PG76-25 30.9% 28.7% 28.6% 29.9% 28.6% 28.6%B6315 CRTB PG82-23 1.0% 0.7% 0.5% 0.6% 1.0% 1.7%B6324 SBS-LG PG68-26 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%B6325 SBS-LG PG77-23 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%B6326 SBS-LG PG84-22 0.1% 0.1% 0.0% 0.1% 0.1% 0.1%B6310 TP PG59-30 5.5% 3.1% 5.3% 0.0% 10.4% 19.4%B6312 TP PG72-31 2.7% 3.2% 3.3% 3.1% 3.4% 3.3%B6316 TP PG82-24 59.6% 59.3% 59.4% 59.3% 59.3% 59.4%

6 of 9 7 of 9 7 of 9 7 of 9 6.5 of 9 5 of 9

Calibration at Lower SST Temperature

Binder\Parameter

Results Results ––Intermediate SST Temp CalibrationIntermediate SST Temp Calibration

|G*| sind




1 of 9 4 of 9 4.5 of 2.5 of 3 of 9 2 of 9

Calibration at Higher SST Temperature

Binder\Parameter

Results Results ––Higher SST Temp CalibrationHigher SST Temp Calibration

|G*| sind




1 of 9 4 of 9 4.5 2.5 3 of 9 2 of 9

Calibration at Higher SST TemperatureBinder\Parameter

ObservationsObservations•• Utilization of the Lower and Intermediate T.T.S. Utilization of the Lower and Intermediate T.T.S.

Calibrations is desired…Calibrations is desired…–– Higher Temp Calibration has strongest potential for Higher Temp Calibration has strongest potential for

variabilityvariability–– Lower and Intermediate compare with each otherLower and Intermediate compare with each other

•• Lower Calibration (7 of 9)Lower Calibration (7 of 9)11--(1/(1/tantanδ δ sinsinδδ) methods and ZSV capture more ) methods and ZSV capture more behaviorbehavior

•• Intermediate Calibration (4~ or 9)Intermediate Calibration (4~ or 9)11--(1/(1/tantanδ δ sinsinδδ) methods and LSV capture more ) methods and LSV capture more behaviorbehavior

Next Steps… Next Steps… High Temperature ParametersHigh Temperature Parameters

•• NonNon--recovered Compliance after 50 cyclesrecovered Compliance after 50 cyclesRepeated Creep Repeated Creep @ @ 50Pa, 100Pa, 500Pa, 1000Pa, 50Pa, 100Pa, 500Pa, 1000Pa, 1600Pa, 3200Pa 1600Pa, 3200Pa (Binder ETG)(Binder ETG)

•• NonNon--recovered Compliance Multirecovered Compliance Multi--stress after 10 stress after 10 cyclescycles Repeated Creep Repeated Creep @ @ 25Pa, 50Pa, 100Pa, 25Pa, 50Pa, 100Pa, 200Pa, 400Pa, 800Pa, 1600Pa, 3200Pa 200Pa, 400Pa, 800Pa, 1600Pa, 3200Pa

(Binder ETG)(Binder ETG)

ACTION ITEMSACTION ITEMS

•• What additional binder should be What additional binder should be considered? considered? –– Is 7 or 9 good enough?Is 7 or 9 good enough?

•• Should additional aggregate structures be Should additional aggregate structures be considered?considered?

Documents

Revised T.T.S. + Statistical Analysis - engineering.purdue.eduspave/old/Technical Info/Meetings... · 15.0 20.0 0 1000 2000 3000 4000 5000 RSCH Cycles to Failure at 74°C 100mm Pavemen