the superpave system – filling the gaps. · 2019. 11. 5. · filling the gaps. john a. d’angelo...

Superpave Future Directions 2/21/01

John D'Angelo 1

The Superpave System –Filling the gaps.

John A. D’AngeloFederal Highway Administration

FHWA Binder labContinuous support to the States:

Training / Ruggedness / Development / Validation

Trouble shooting of binder problems.


John D'Angelo 2

New Low Temp. SpecificationCombines the results of the BBR and DT.

Thermal stress compared to strength.


John D'Angelo 3

Specification Comparison

-40

-34

-28

-22

-16

-40 -34 -28 -22 -16

Current Spec

Prop

osed

Spe

c

AAA-1 AAB-1 AAD-1 AAF-1 AAM-1Lamont #1 Lamont #3 Lamont #6 Lamont #7

Proposed MP1a Spec.

Binder Tcr Current Spec Tcr Proposed Spec

70-22 Air Blown -24.5 -22.570-22 Conventional -25.1 -22.570-22 SBS Modified -26.0 -30.5Chemically Modified 64-28 A -29.0 -28.0Chemically Modified 64-28 B -27.5 -27.0Chemically Modified 64-28 K1 -29.5 -27.5Chemically Modified 58-28 M1 -27.3 -27.0Elvaloy Modified 64-34 DP -34.7 -36.0


John D'Angelo 4

Binder High Temp PropertiesStudy same mix different binders.

PG 64-22 mod. no rutting PG 64-22 unmod. 15mm rutting

Binder High Temp PropertiesNew test procedure to evaluate binders.

0.0

0.2

0.4

0.6

0.8

1.0

0 2.5 5 7.5 10

time, s

Nor

mal

ized

Stra

in

BM (PMA)

HSK(Conventional)

εac c HSK

εac c BM


John D'Angelo 5

DSR Creep TestingTesting 3 different PG 82's

02468

101214

0 200 400 600 800 1000 1200

Time

Accu

mul

ated

Str

ain

SBRPEOxd

Comparison of Specification Values for Binders with a Value of G*/sin d = 1KPa as a Function of the

Phase Angle

0

1

2

3

4

5

55 60 65 70 75 80 85 90

Delta

G*(f(

d)

1/sin dAroon's f(d)

M&R's f(d)


John D'Angelo 6

Binder Fatigue Test:Time Sweep in the DSR

StressStress

StrainStrain

ττττττττmaxmax

γγγγγγγγmaxmax

Binder Fatigue PropertiesFa tigue o f Asp hal t B in der s

0 .00 E+ 00

2 .00 E+ 04

4 .00 E+ 04

6 .00 E+ 04

8 .00 E+ 04

1 .00 E+ 05

1 .20 E+ 05

0 .00 E+ 00 2 .00 E+ 04 4 .00 E+ 04 6 .00 E+ 04 8 .00 E+ 04 1 .00 E+ 05 1 .20 E+ 05 1 .40 E+ 05 1 .60 E+ 05

Number of c ycles

Dis

sip

ated

En

erg

y R

taio

W i = 1 0 00 P a

W i = 5 0 00 P a

W i = 1 0 00 0 P a


John D'Angelo 7

Binder Characterization

Strain Sweeps @ G*= 5000kPa

35

40

45

50

55

60

65

70

0 5 10 15 20 25 30

strain

pha

se a

ngle

Flux

BaseUnMod 70 -28

Air-BlownElvalo y

SBS-Linear Graft edSBS-Linear SBS-Radial Graft ed

EVAEVA- Gr afted

N/A

Fine aggregate specific gravity test

Measure Temp & Moist. in

Measure Temp & Moist. out

Test controls FAA and VMA

Current procedure highly variable

New test will reduce variability by taking out operator error.


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New Specific Gravity Equipment

90-05 Agg. Gravity ProcedureProduction version under development.


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90-05 Agg. Gravity ProcedureProduction version under development.

Gyratory Comparisons


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Analysis of 30 Production MixesF test & Student “ t ” test

3.142 < 2.0421.30 < 2.07Design

Critical“ t ” value

Calculated“ t ” value

CriticalF value

CalculatedF value

Gyrations

There is a measurable bias between the two compactors. On average the one unit’s Gmb is 0.005 higher. However, this is well within T 166’s precision (0.02).

Standard Deviation Average (Mean)

KeyUniform procedures between the two mobile laboratories

AASHTO PP XX-01, “Standard Practice for the Evaluation of Different SGC’s used in the Design and the Field Management of Superpave Mixes”

Routine maintenance and calibrationwas performed


John D'Angelo 11

Not Every Day is a Good Day!Not Every Day is a Good Day!Not Every Day is a Good Day!

We are seeing measurabledifferences in the field.

State DOT expressed concern regarding measured differences in specimens compacted in SGC’s between the Stateand several local Contractors

Differences as high as1.5 % air voids !


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Angle DefinitionsHow parallel?How perpendicular?

��FIXED REFERENCE PLANE

Gyratory Internal Measuring Device


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State DOT vs ContractorBased on the data, how would you expect the compactors to compare?

0.951.001.051.101.151.201.251.30

STATE CONTRACTOR

FindingsBased on the limited testing, the Contractors SGC appears not to be maintaining the internal angle of gyration dynamically.

Also, the DOT’s SGC appears to be operating on the high side if the specification.


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The Kit Only in the Mold

1.27

1.33

1.381.42

1.48

y = 1.02 x

R2 = 0.995

1.20

1.25

1.30

1.35

1.40

1.45

1.50

1.55

1.60

1.20 1.25 1.30 1.35 1.40 1.45 1.50

External Angle Setting, degrees

Kit

Angl

e

HMA and the Kit in the Mold

1.16

1.20

1.25

1.30

1.36

y = 1.02 x - 0.12R2 = 0.997

1.10

1.15

1.20

1.25

1.30

1.35

1.40

1.45

1.50

1.20 1.25 1.30 1.35 1.40 1.45 1.50

External Angle Setting, degrees

Kir

Ang

le


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Vision

“Future validation will be based upon an angle of gyration, measured dynamically, under load of a specimen.”

What Do We Do Now

Interim Step – is to use a procedure to compare compactors and determine an offset between them.


John D'Angelo 16

Gyratory Internal Measuring Device

FHWA Mobile Asphalt Lab


John D'Angelo 17

Mobile Asphalt Labs Provide “Hands-on” of Superpave System

Volumetric Mix DesignField QC/QA Procedures, NCHRP 9-7Simple Performance Test Device, NCHRP 9-19Performance Related Specifications 9-22

4 to 6 week visitsData used to support ETG’s

Superpave SpecificationsRoadway Densities

Specifications the same, mixes different.


John D'Angelo 18

Superpave Specifications

Contrasting Stone Skeletons

Superpave SpecificationsRoadway Densities.

Lift thickness does effect compaction.Recommended lifts should be 3 to 4 times nominal maximum size or 2 1/2 to 3 times max size.


John D'Angelo 19

Superpave Compaction

X-ray Tomography System

X-Ray Source

Detector

Specimen

Collimator(window)


John D'Angelo 20

Image Processing-Air Voids

Air Void

Asphalt Binder

Aggregate

Vertical distribution of Air Voids in Gyratory Specimens and Field Cores

0

10

20

30

40

50

0 4 8 12 16 20 24

Air Voids (%)

Dep

th (

mm

) FC-1 -13FC-1 -19FC-2 -18FC-2 -9FC-3 -12FC-3 -25

Fie ld Core s

020406080

100120140

0 4 8 12 16 20 24Air Voids (%)

Dep

th (m

m) LHCC

LLCCHHCCLHHC

Gyratory Spec ime n


John D'Angelo 21

90-03 Mix TendernessStudy variables

Determine effect of moisture on mix properties.• Procedure developed to produce mix with 2%

mois ture in agg.

Measure moisture in plant mix.• Develop procedure to determine actual measure in

plant mix.

Superpave CompactionMix Tenderness

Study underway with the Asphalt Institute.Major cause of tenderness is moisture Minor affect gradation


John D'Angelo 22

90-03 Mix TendernessProducing Mix With High

Moisture

90-03 Mix TendernessMoisture Effects mix


John D'Angelo 23

SUPERPAVE PERFORMANCE

MODELS

Proposed Changes to the Long-Range Plan for 2005

Superpave Performance Models and Test Methods

1999 - 2002: NCHRP Project 9-19, Superpave Support and Performance Models Management

Complete all tasks begun in FHWA project.

1998 - 2001: NCHRP Project 1-37A, Development of the 2002 Guide for the Design of New and Rehabilitated Pavement Structures

Mechanistic-empirical HMA performance models.


John D'Angelo 24

Original 1999 PlanProject 9-19: Materials characterization model and test.Future Projects: Mechanistic models for non-linear, viscoelastic HMA behavior based on 3-D finite element analysis and similar advanced computing techniques. Realistic completion date: 2007 or 2008.Estimated future funding: $7.65 million.

Revision of the Long-Range Plan for 2005

NCHRP Project Panels 9-19 and1-37ATRB Superpave CommitteeAASHTO Standing Committee on Research


John D'Angelo 25

Revised PlanUse HMA performance models and integrated climatic model from the 2002 Design Guide (Project 1-37A) for Superpave mix analysis and, possibly, HMA PRS (Project 9-22). Realistic completion date: 2004 or 2005.Estimated future funding: $1 -2 million.

Revised PlanSuperpave effort finished on schedule.Common tools for HMA mix design, structural design, and PRS.Common materials characterization test; reduced need for new equipment; simplified technician training.Next generation of multi-use, mechanistic HMA performance models developed with minimal duplication of effort.


John D'Angelo 26

NCHRP 9-19 s imple performance test. Preliminary evaluation currently underway.

The Superpave SystemSuperpave is in place and it does work.There is a great deal of work needed to fill gaps in the system.Work is continuing to fill the gaps.A plan is in place to complete the system by 2005.


John D'Angelo 27

Thank You

the superpave system – filling the gaps. · 2019. 11. 5. · filling the gaps. john a. d’angelo...

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