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Using the Gyratory Pressure Distribution Analyzer GPDA to Estimate Compaction Resistance of HMA Hussain Bahia and Andrew Hanz University of Wisconsin - Madison Francois Malassenet and Tom Brovold Troxler

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Page 1: Using the Gyratory Pressure Distribution Analyzer GPDA …uwmarc.wisc.edu/files/2009_Troxler_UsingTheGyratoryPressure... · Using the Gyratory Pressure Distribution Analyzer GPDA

Using the Gyratory Pressure Distribution Analyzer GPDA to Estimate Compaction Resistance of HMA

Hussain Bahia and Andrew HanzUniversity of Wisconsin -

Madison

Francois Malassenet and Tom Brovold Troxler

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Background • Best mixture design should include:

Volumetrics and resistance to compaction for production, and

performance testing for traffic/climate • Difficulty:

No current system for compaction resistance–

Performance testing requires more equipment and time.

• Can the SGC be used to address both?–

Compactive Effort - Workability

Aggregate Interlock - Stability

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History of Using The Gyratory To estimate shear resistance

•McRae –

Gyratory Testing Machine –

1960’s and 1970’s

•Goetz, Ruth, and others recommended using GTM for mix design to measure stability –

1980’s and 1990’s

•France, Australia, and Finland have used the Gyratory for mixture evaluation –

1980’s and 1990’s

• In 1993 the Superpave Gyratory Compactor was adopted in the U.S.

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Better Utilization of SGC Since 1996-Not a new topic !•1996: Use densification slope

Relationship to Mixture G*

•1998: Use densification curves to define–

Resistance to compaction

Resistance to traffic

•2000: Use gyratory with GLPA to measure shear between aggregates –

Resistance to compaction & to traffic

•2002: NCHRP 9-16

(Anderson et al.)–

Gyrations at maximum stress relate to field rutting

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Superpave Volumetric Design Criteria

Log

Gyrations

% Gmm

10

100

1000

Nini

NdesNmax

600 kPa

1.16 deg

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Construction•CFI•Nini to 92% Gmm

Traffic•TFI•92% -

98%

Gmm

Schematic –

Force Indices

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HMA Basics: Rocks + Asphalt + Air Voids

Stability of HMA:1.Rock- to – rock contacts2.Binder rheology

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What actually happens in the Superpave Gyratory Compactor?

R

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9

R

Mix A

Strong aggregate interlock

Large Moment

Example 1: Behavior of a “Good Mix”

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10

Mix B

Less aggregate interlock

Small Moment

R

Example 2: Behavior of a “Bad Mix”

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Use of the Shear Plate (GPDA) to Calculate Eccentricity of load

2yy

2x

xy

y

)er(ee

e0M

e0M

x

R = P1

+ P2

+ P3

M(t) = R * e(t)

eR

Ram

GLPA

Mold

HMA Sampleo

1.25

x

y

ey

eO

P2

ex

P3

P1

ry

120o

The Pressure Distribution Analyzer

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GPDA Used in the SGC Compaction Mold

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2D Eccentricity plots for HV2 and HV5 samples at 6.5 % asphalt content

HV2HV5

Sample of Collected Data and Typical Analysis

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Sample of Collected Data and Typical Analysis (continued)

-1.5-1

-0.50

0.51

1.5

-1.5-1

-0.50

0.51

1.50

100

200

300

400

500

600

Ex (in.)Ey (in.)

Num

ber o

f Gyr

atio

ns

HV5

-1.5-1

-0.50

0.51

1.5

-1.5-1

-0.50

0.51

1.50

100

200

300

400

500

600

Ex (in.)Ey (in.)

Num

ber o

f Gyr

atio

ns

HV2

3D Plots for HV2, HV5 (at 6.5% asp. content

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0 100 200 300 400 500 6000

200

400

600

800

1000

1200

1400

1600

1800

2000

Number of Gyrations

Load

Cel

l For

ce (l

bs)

HV5-L. Cell Max/Min. Force

0 100 200 300 400 500 6000

200

400

600

800

1000

1200

1400

1600

1800

2000

Load

Cel

l For

ce (l

bs)

Number of Gyrations

HV2-L. Cell Max/Min. Force

Sample of Collected Data and Typical Analysis (continued)

Load Cell force distributions versus number of gyrations for HV2 and HV5 mixtures

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Sample of Collected Data and Typical Analysis (continued)

Combine force measurements and volumetrics to calculate workability and stability indices.

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The Resistive Effort (ω)

Where–

w : the resistive effort (kPa)–

e: the eccentricity of resultant force (m)–

P : the magnitude of resultant force (kN)–

: the angle of tilting (1.16)–

A : the area of specimen (m2)

h: the height of specimen at any given gyration (m)

AhePw 4

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Stress Analysis: Masad et al

tan21cos)( 12 dWPNNS av

dsdvdu

2G

1G

N

NeN dS EIC

dv= volume change energyds= shear change energy

Masad, et al. “Quantifying Laboratory Compaction Effects on the Internal Structure of Asphalt Concrete.”

Transportation Research Record 1681. Transportation Research Board of the National Academies. Washington D.C., pp 179-185, 1999.

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19

Comparing Mixes: Volumetrics vs. GPDA

100

101

102

103

75

80

85

90

95

100

% G

mm

100

101

102

1030

36

72

108

144

180

100

101

102

1030

36

72

108

144

180

Number of Gyrations

Fric

tiona

l Res

ista

nce

(kPa)

Frictional Resistance-HV2-6%Frictional Resistance-HV2-5%% Gmm-HV2-6% % Gmm-HV2-5%

Forc

e

Dens

ity

Δ

Density

Δ

Force

Page 20: Using the Gyratory Pressure Distribution Analyzer GPDA …uwmarc.wisc.edu/files/2009_Troxler_UsingTheGyratoryPressure... · Using the Gyratory Pressure Distribution Analyzer GPDA

20

Experimental Program

•Four sources of Aggregates•Two gradations•Various levels of fine aggregate angularity•Two PG Grades

•Used PDA to collect shear data

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Experimental Plan

0

10

20

30

40

50

60

70

80

90

100

0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00 90.00 100.00

Sieve Sizes

% P

assi

ng

A05 A01 A02 A03 A04

`

`

12.5mm NM size

19mm NM size

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Results-

Construction

(CFI)

Average CFI values for all mixes

A01

A02 A03

A04

A05

B01

B02

C01

C02

D01D02

0

200

400

600

800

1000

1200

CFI

A01 A02 A03 A04 A05 B01 B02 C01 C02 D01 D02

~10

Tim

es D

iffer

ence

eR

Ram

GLPA

Mold

HMA Sampleo

1.25

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Measuring Traffic Resistance Index (TFI) with the PDA

A01

A02A03 A04

A05

B01

B02

C01

C02

D01

D02

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

TFI

A01 A02 A03 A04 A05 B01 B02 C01 C02 D01 D02

Average TFI values for all mixes

eR

Ram

GLPA

Mold

HMA Sampleo

1.25

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Effects of Warm Mix Additives on Workability (CFI)

050100150200250300350400450

80 100 120 140

CFI

Temperature  (?C)HMA Advera ‐ 6%

Revix ‐ 0.5% Foam ‐ 1.5%

0

50

100

150

200

250

300

350400

450

80 100 120 140

CFI

Temperature (?C)HMA Advera ‐ 6%Revix ‐ 0.5% Foam ‐ 1.5%Rediset‐2%

050100150200250300350400450

80 100 120 140

CFI

Temperature (οC)HMA Advera ‐ 6%

Revix ‐ 0.5% Foam ‐ 1.5%

0

50

100

150

200

250

300

350

400

450

80 100 120 140

CFI

Temperature (οC)HMA Advera ‐ 6%Revix ‐ 0.5% Foam ‐ 1.5%Rediset‐2%

PG 64-22 PG 76-22

HMA

WMA

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Correlation between GPDA and rutting : TFI vs. Rate of Deformation

y = 5838.6x-0.5927

R2 = 0.7893

0

2000

4000

6000

8000

10000

0 10 20 30 40 50 60

Rate of Deformation

TFI

Rate of Deformation in Rutting Tests

eR

Ram

GLPA

Mold

HMA Sampleo1.25

TFI

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26

Correlation between GPDA and Rutting: TFI vs. Flow Number

eR

Ram

GLPA

Mold

HMA Sampleo

1.25

y = 1.0541x + 57.333R2 = 0.809

0

2000

4000

6000

8000

10000

12000

0 2000 4000 6000 8000 10000

FN

TFI

eR

Ram

GLPA

Mold

HMA Sampleo1.25

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Proposed Criteria Workability

Stability

Mixture Type Traffic Level (Million ESALS) Maximum CFI

E-3 <3 250E-10 3 to <10 300E-30 10 to <30 400

Mixture Type Traffic Level (Million ESALS) Minimum

TFI

E-3 <3 800E-10 3 to <10 1000E-30 10 to <30 1600

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Recommendations

The SGC be used as a tool for mixtures:–

Evaluate effect of gradation and WMA additives–

Workability –

Estimate rutting resistance -

Stability

It is recommended that –

Workability

and Stability

be included in

evaluation of mix designs to allow for optimum materials selection.

Conduct performance testing when possible.

Page 29: Using the Gyratory Pressure Distribution Analyzer GPDA …uwmarc.wisc.edu/files/2009_Troxler_UsingTheGyratoryPressure... · Using the Gyratory Pressure Distribution Analyzer GPDA

Concluding Remarks

•There is no substitute for performance testing of asphalt mixtures

•We can, however, reduce possible combinations of mixture variables using the SGC and GPDA measurements.

•GPDA results can be better used to study– Workability –

Warm Mix

– Stability –

Modification/Gradation