Advances in performance evaluation of asphalt binders Bahia.pdf · Advances in performance evaluation of asphalt binders Road Materials and Pavement Design Pavements: Materials, design

Advances in performance evaluation of asphalt binders

Road MaterialsandPavementDesign

Pavements: Materials, design and performance

Lisboa, LNEC, 25 March 2010

Hussain U Bahia

Professor

University of Wisconsin, USA

March 25, Lisbon, Potugal


Outline

>Performance grading (PG) background

>PG plus in USA

>New Concept:Damage Resistance Characteriztaion

Road Pavements: Materials, design and performance


�Rutting Resistance o Multiple Stress Creep and Recovery

�Fatigue Resistance o Binder Yield Energy Test

o Linear Amplitude Sweep

�Bond strength- cohesion and adhesion

�Fracture Testing


Cold Temp.Cracking

Fatigue Cracking Rutting

Mixing &Paving

Performance Grading and Modified (Engineered) Bitumen



Temperature

Typical Asphalt

Ideal (modified) Asphalt

Stiffn

ess, G

*

PMB

WMA

Superpave Bitumen Tests

DSR

Dynamic Shear

DT

Related to Performance!

• Climate -- PG HT-LT

• Traffic Speed – DSR

• Traffic Volume – PG shift



RV

RotationalViscometer

Dynamic Shear Rheometer

BBR

Bending Beam Rheometer

Direct Tension Test

• Traffic Volume – PG shift

• Traffic loading – NA

• Pavement Structure – NA

• Assumption:

Bitumen in Linear VE

range


The focus on Linear Visco-elasticity: G*, delta

1E+04

1E+05

1E+06

Co

mp

lex

Mo

du

lus

(P

a)



1E+00

1E+01

1E+02

1E+03

1E+04

45505560657075808590

Co

mp

lex

Mo

du

lus

(P

a)

<< Viscous Phase Angle delta (°) Elastic >>

Low SBS %

No polymer network

Viscous above 60°C

Reasonably workable

High SBS %

Polymer network

Elastic during compaction

Workability problem

Courtesy of

Nynas


Performance Grading –Redefined (2001)

>Linear VE is not

sufficient (NCHRP 9-10)

>Bitumen damage resistance

σf



is very important

>Modified bitumen are best

in damage resistance

Strain εf

LVE

Non-Linear

-- Damage

Evolution of PG Bitumen Specification P

erfo

rma

nce

In

dic

ato

rs

S, m, Tg, Fracture Energy

Nf

Adhesion



Per

form

an

ce I

nd

ica

tors

Jnr

Temperature

Tmin Tavg Tmax

η= 3.0 η= 3.0 η= 3.0 η= 3.0 pa-s

135 C 160 C

ηι= 6.0 ηι= 6.0 ηι= 6.0 ηι= 6.0 pa-sJnr

Adhesion

Current Test: Cyclic Loading

-10000

0

10000

20000

30000

40000 Strain 2%

Strain 25%

Strain 50%

Stress/Stress/

StrainStrain

γγγγγγγγ22

ττττττττ22



-40000

-30000

-20000

-20000 -10000 0 10000 20000

Torque (stress)

Can only give total energy:

Total W= π .τi2 .sin δ/ G*

= Welastic+ Wdelayed elastic+ Wviscous

The new tests : Creep and Recovery (MSCR)

DSR 0.1

68

Shear Stress, kPa

0.7 1.4



DSR

Dynamic Shear Rheometer

0.1 0.7 1.4

0.1

Shear Stain, mm/mm

0.7 1.4

Accumulated Strain

Binders with same G*/sinδ but different recovery

10%

12%

14%

PG82- Oxidized (1 cycle)

PG82 - Oxdized (100 cycle)



0%

2%

4%

6%

8%

0 2 4 6 8 10 12

Time (s)

Str

ain

PG82-SBSr (1 cycle)

PG82- PEs (1 cycle)

PG82-SBr (100 cycle)

PG82-PEs (100 cycle)


Binder Rutting Parameter

>The creep compliance, J(t), in terms of itselastic component (Je), the delayed-elastic(Jde), and the viscous component (Jnr):



>Calculate the viscous compliance (Jnr).

vdee JJJtJ ++=)( nr


Binder Fatigue Data

1,E+07

1,E+08

Dy

na

mic

Sh

ea

r M

od

ulu

s [P

a]

Time Sweep - 5% Applied StrainALF Control

ALF CR-TB

ALF Terpolymer

ALF SBS-LG

TPF Control A

TPF PG64-34 A

TPF PG76-22 A

TPF PPA A



1,E+05

1,E+06

1,E+07

1,E+01 1,E+02 1,E+03 1,E+04 1,E+05

Dy

na

mic

Sh

ea

r M

od

ulu

s [P

a]

Time (Cycles/Frequency) [sec]

TPF PPA A

TPF Latex A

AASHTO Standard for Binder Yield Energy (BYE)



Yield Energy Evaluation of different binders




Linear Amplitude Sweep (LAS)Need 2 tests for VECD analysis

15

20

25

Ap

pli

ed

Str

ain

[%

]

Amplitude Sweep Loading Scheme

1,E+05

1,E+06

Sh

ea

r R

ela

xati

on

Mo

du

lus

[Pa

]

Stress Relaxation Test Results

+



0

5

10

0 500 1.000 1.500 2.000 2.500

Ap

pli

ed

Str

ain

[%

]

Loading Cycles

1,E+03

1,E+04

1 10 100 1000

Sh

ea

r R

ela

xati

on

Mo

du

lus

[Pa

]

Time [s]

+

Relaxation /freq Sweep Amplitude Sweep


AASHTO Draft Procedure




VECD Analysis of LAS – Damage Curve

Damage equation following Yong-Rak Kim & D. Little work (2006):0,60

0,80

1,00

No

rma

lize

d |G*

|si

n δδ δδ

LAS VECD Analysis

64-28 SBS

64-34 ELV

58-34 ELV

64-28 NEAT



( )[ ] ( ) αα

α

δδγπ +−

=

+− −−⋅⋅≅∑ 1

1

1

1

11

2

0 sin*sin*)( ii

N

i

iiD ttGGItD

0,00

0,20

0,40

0 1.000 2.000 3.000 4.000 5.000

No

rma

lize

d |

Damage Intensity


VECD Fatigue Prediction Model

>With the VECD curve fit to a simple numeric equation:

>Fatigue life can be predicted using:



>Fatigue life can be predicted using:

k = 1 + (1 – C2)α


Simulated Fatigue

1,E-02

1,E-01

1,E+00

1,E+01

Nf / ESAL's

Fatigue Law: Nf = A(γ0)B

[Traffic Volume

A

B



1,E-05

1,E-04

1,E-03

1,E-02

1 10

Nf / ESAL's

Applied Shear Strain [%][Pavement Structure Indicator]

[Traffic Volume

Indicator]


[Nf/ESAL’s]

Pavement Structure:Weak(400µε)

Strong(200µε)

Binder Qualification ExampleEffects of Traffic and Pavement Structure

>For unmodified PG70-22 binder, Nf = A×(γ0)B

�A: 3.89 × 106

�B: -5.277



Pavement Structure:Weak(400µε)

Strong(200µε)

Traffic[ESAL’s]

(S) 1,000,000

0.10 3.86

(H) 3,000,000

0.03 1.29

(VH) 10,000,000

0.01 0.39

PG70-22 H

Modified BBR to Test for Fracture



FEM simulations of two different geometries New BBR Geometry:

=>Continuity of stresses

=>Plane sections remain

plane after bending



plane after bending

SENB Example Results

15000

20000

25000

30000

35000

Lo

ad

(m

N)

Sample 1

Sample 2

Sample 3

Sample 4

32000

36000PPS = 252

pulses/step = 2Limestone

Mastic

Binder



0

5000

10000

0 0.1 0.2 0.3 0.4 0.5

Displacement (mm)

Lo

ad

(m

N)

0

4000

8000

12000

16000

20000

24000

28000

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40

Displacement (mm)

Lo

ad

(m

N)

Granite

Limestone

Constructed 27/04 and

trafficked for 1 warm day

Constructed 29/04

Temperature drop 30/04

Bitumen Adhesion



Source: Gerrie Van Zyl – RSA


Bitumen Bond Strength Testing Apparatus

Graded Scale for Air Flow Control




Example of Test Results

40

7


Lisboa, LNEC, 25 March 2010January 05, 2010 4

6

5

0.820

22

15

Cohesive Failure Adhesive Failure


Results and Analysis:

Effect of Conditioning Time in Tap Water

2000

2500

3000

off

T

ensi

le

Str

eng

th

(KP

a)

Limestone

2000

2500

3000

off

T

ensi

le

Str

eng

th

(KP

a)

Granite



0

500

1000

1500

Pu

ll-o

ff T

ensi

le

Str

eng

th

(KP

a)

0 hour

6 hours

24 hours

0

500

1000

1500

Pu

ll-o

ff T

ensi

le

Str

eng

th

(KP

a)

0 hour

6 hours

24 hours

January 05, 2010 18


BBS Relationship to Performance

Tensile Strength > 125 psi yield <10% chip loss. Curing time ~ 6 hours.



hours.

Acknowledgments

Mrs. Maria de Lurdes Antunes

Mr. Jorge Barreira de Sousa

National Civil Engineering Labs



Questions

Please write to me:

Hussain U. Bahia

[email protected]

Documents

Advances in performance evaluation of asphalt binders Bahia.pdf · Advances in performance evaluation of asphalt binders Road Materials and Pavement Design Pavements: Materials, design