development and application of the asphalt mix performance tester

Advanced Asphalt Technologies, LLC

“Engineering Services for the Asphalt Industry”

Development and Application of the

Asphalt Mix Performance Tester

Ramon Bonaquist, Ph.D., P.EAdvanced Asphalt Technologies, LLC



Outline

• What is the Asphalt Mixture Performance Tester?

• Why was it developed?• What tests can be conducted?• How can I use the data?• What’s next?



What is the AMPT?

• NCHRP 9-29• Servo-Hydraulic

Machine• HMA Testing

– Mix Design– Structural Design– Evaluation



AMPT Capabilities

• Three Performance Related Tests– Dynamic Modulus– Repeated Load– Creep

• Temperature Control– 4 to 60 °C

• With and Without Confinement– 210 kPa Max

• Fatigue Test Under Development



Key AMPT Features

• Rugged– Proven Hydraulic System

• Automated Testing Cell– Temperature– Confining Pressure

• Easy to Install Instrumentation• Standard Software

– Testing and Analysis– Data Quality

• Technician Friendly



Why Do We Need the AMPT?

• Test to Indicate How a Mix Will Perform– Rutting– Cracking

• Uses– Identify Inferior Mixtures– Structural Design– Evaluations



SHRP Mixture Tests

• Shear Test AASHTO TP7– Modulus– Permanent Deformation

• Flexural Fatigue AASHTO TP8– Fatigue Cracking

• Indirect Tensile Test AASHTO TP9– Thermal Cracking



Issues With SHRP Products

• High Costs– Equipment– Training

• Used With Performance Models– Errors– Not Calibrated– Not User Friendly



Post SHRP

• National Cooperative Highway Research Program (NCHRP)

• Considered– Gyratory Compactor

– Asphalt Pavement Analyzer

– Fundamental Tests



Recommended Tests

• Dynamic Modulus– Rutting– Cracking

• Repeated Load Test– Rutting

• Creep Test– Rutting



Dynamic Modulus Test

0

0*

E

Stress

Strain

Time

• Rutting– Min |E*| at High Temp

• Fatigue Cracking– Max |E*| at Intermediate

Temp



Repeated Load Test

ST

RA

IN

Flow Number

• Rutting– Min FN at High Temp

TIMES

TR

ES

S



Creep Test

ST

RA

IN

Flow Time

TIMES

TR

ES

S

• Rutting– Min FT at High Temp



SPT Uses

• Dynamic Modulus Master Curve for Structural Design– AASHTO MEPDG

• Mixture Design– NCHRP Project 9-33 “Mix Design

Manual for Hot Mix Asphalt”

• Material Evaluations– Homogenity of RAP Mixtures



Pavement Structural Design

• AASHTO Mechanistic-Empirical Pavement Design Guide– HMA Characterized by a Dynamic

Modulus Master Curve• Plant Aged Conditions

– Modulus Needed• Stress-Strain Analysis• Rutting Model• Fatigue Cracking Model



1

10

100

1000

10000

0.0001 0.001 0.01 0.1 1 10 100 1000

Reduced Frequency, Hz

Dy

na

mic

Mo

du

lus

, k

si

4 C

20 C

40 C

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

0 5 10 15 20 25 30 35 40 45

Temperature, C

Sh

ift

Fa

cto

r

Temperature and Loading Rate Effects

|E*| Master Curve



NCHRP 9-29 Draft Practice

• Developing Dynamic Modulus Master Curves for Hot-Mix Asphalt Concrete Using the Asphalt Mixture Performance Tester– Testing Conditions

• Temperature• Frequency

– Replicates– Data Analysis

• Excel Spreadsheet



2-3 in

Rutting Resistance

• Shear Deformation - Major• Densification - Minor• High Temperatures• Early in Pavement Life

Rutting Mechanism



Repeated Load Test

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 1000 2000 3000 4000 5000 6000

Load Cycle

Pe

rma

ne

nt

Str

ain

, %

0.0000

0.0005

0.0010

0.0015

0.0020

0.0025

0.0030

0.0035

0.0040

0.0045

0.0050

Pe

rma

ne

nt

Str

ain

Ra

te, %

pe

r C

yc

le

Permanent Strain Permanent Strain Rate

Flow Number = Minimum Permanent Strain Rate



NCHRP 9-33 Tentative Criteria

• Stress Level– 600 kPa (87 psi)– Database of Mixtures Tested by FHWA

• Temperature– 50 % Reliability Design Temperature

From LTPPBind 3.1

• Short Testing Time



NCHRP 9-33 Tentative Criteria

100

1,000

10,000

1 10 100 1,000 10,000

Estimated Maximum MESALs

Flo

w N

um

ber

MESALFlowNumber

3 --3 to <10 340

10 to <30 56030 890



Mixture Homogenity

• How Well Does the RAP/RAS Binder Mix with the New Binder?– Black Rock– Complete Mixing

• Process Specific– Plant Type– Plant Operations– RAP/RAS Processing



One Tool

• Dynamic Modulus – Test Is Highly

Sensitive to Binder Stiffness• Assess Degree of

Mixing of New and Recycled Binders

– Relatively Easy to Perform with the AMPT



How?

• Perform Dynamic Modulus Tests on Plant Produced Mixture– Plant Mixed Condition

• Recover Binder, Test and Estimate Dynamic Modulus Using Predictive Model– Fully Blended Condition

• Compare Measured and Estimated



Good Mixing

1

10

100

1000

10000

4 C

, 10

Hz

4 C

, 1 H

z

4 C

, 0.1

Hz

20

C, 1

0 H

z

20

C, 1

Hz

20

C, 0

.1 H

z

40

C, 1

0 H

z

40

C, 1

Hz

40

C, 0

.1 H

z

Testing Condition

Dy

na

mic

Mo

du

lus

, k

si

Measured Estimated for Complete Mixing



Poor Mixing

1

10

100

1000

10000

4 C

, 10

Hz

4 C

, 1 H

z

4 C

, 0.1

Hz

20

C, 1

0 H

z

20

C, 1

Hz

20

C, 0

.1 H

z

40

C, 1

0 H

z

40

C, 1

Hz

40

C, 0

.1 H

z

Testing Condition

Dy

na

mic

Mo

du

lus

, k

si

Measured Estimated for Complete Mixing



Implementation

• Interlaboratory Study– NCHRP 9-29

• Pooled Fund Study 5(178)– Purchase Equipment for Interested

Agencies– 2 Day Training Course– Coordinated Studies

• Improve Criteria



AMPT Summary

• Specifically for HMA Testing• Three Performance Related Tests

– Dynamic Modulus– Repeated Load– Creep– Fatigue Test Under Development

• User Friendly, Second Generation Mixture Performance Testing Equipment

• Extensive National Efforts to Develop and Implement



AMPT Uses

• Dynamic Modulus Master Curve for Structural Design– AASHTO MEPDG

• Mixture Design– NCHRP Project 9-33 “Mix Design Manual for Hot

Mix Asphalt”

• Material Evaluations– Homogenity of RAP Mixtures– Forensics– Others



Questions

Ramon Bonaquist, P.E.Chief Operating Officer

Advanced Asphalt Technologies108 Powers Court, Suite 100

Sterling, VA 20166703-444-4200

[email protected]

development and application of the asphalt mix performance tester

Documents

hzdynamic modulus

test data

mix design manual

eadvanced asphalt technologies

high tempfatigue crackingmax

c20 c40 cfrequency

master curvechart1 2chart1

c20 c40 creduced frequency