Modified Asphalt Binders – Enhancing Pavement Performance. Vo… · Modified Asphalt Binders – Enhancing Pavement Performance Harold L. Von Quintus, ... adopted the P-G specifications

S1SP ARA0127-1

Modified Asphalt Binders –Enhancing Pavement

Performance

Harold L. Von Quintus, P.E.

51st Annual Idaho Asphalt ConferenceOctober 27, 2011

Expanding the Realm of Possibility2

Focus● Overview the effect of modified

asphalt binders for enhancing pavement performance – extending the service life of new pavements and overlays.


Effect of Binder on Performance

1. Thermal Cracking2. Fatigue Cracking3. Rutting

Most, if not all agencies in U.S. have adopted the P-G specifications & many have reported reduced distress; especially thermal cracking.

Expanding the Realm of Possibility

Effect of Binder on PerformanceImproved pavement performance

observations after implementing P-G binder specificationMinistry of Transportation, OntarioColoradoMichiganMissouriUtah

4

BUT, other changes made: Gyratory compactor, use of polymer modified asphalt, revised QA specifications,

pavement preservation, etc.


Michigan:Distress Index –systematic reduction over time.

5


Effect of BinderDifficult to quantify because multiple changes made or materials implemented within the same time period.Asphalt binders by themselves will not significantly improve performance – my opinion.

6

HISTORY: Many laboratory studies have shown PMA enhances fracture and

distortion resistant properties – BUT field quantification of benefit is limited.

S1SP ARA0127-7

Performance Comparisons:Neat versus Modified Binders

Quantification of the Effects of Polymer-Modified Asphalt to Enhancing HMA

Performance, Sponsored by the Affiliate Committee, Asphalt Institute.


Distress Comparison for Companion Sections 1. Fatigue Cracking; Area &

longitudinal combined2. Rutting3. Thermal Cracking

Companion Sections – Two sections where the only difference is the asphalt

binder.


PMA Versus Neat SectionsComparison of Actual Distresses

RuttingFatigue CrackingTransverse Cracking

M-E Analysis of Performance DistortionFracture

M-E Based Procedure normalizes any difference between companion sections.


Rutting

Neat MixesVersus

PMA Mixes


What is the time difference between different rut depths?

0

0.2

0.4

0.6

0.8

1

1.2

0 0.5 1

Rut Depths on PMA Sections, inches

Rut

Dep

ths

on C

onve

ntio

nal

Sect

ions

, inc

hes

Years for equal rutting?


Distortion AnalysisVertical strain at specific depthsNeat sections individually calibrated & used to predict PMA rutting.

RNnDI =

HMA Surface

HMA Base

Granular Base

Subgrade

εV

εV

( )( ) ( )

( ) ( ) ( )( )( )( )

∑=

−

⎟⎟⎟⎟

⎠

⎞

⎜⎜⎜⎜

⎝

⎛

=n

i

ir

abeff

Cr

tC

VVT

NCx

RD

r

13

5213.00057.15896.2

4289.01

7 21037.5

ε


Rutting – Neat Vs PMA

00.10.20.30.40.50.60.70.80.9

1

0 0.2 0.4 0.6 0.8 1

Predicted Rut Depth - Local Calibration, inches

Mea

sure

d R

ut D

epth

, inc

hes

Companion Sections Line of Equality Modified Sections


Cracking

Neat MixesVersus

PMA Mixes


What is the time difference between different amounts of cracking?

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

0.00 20.00 40.00 60.00 80.00

Fatigue Cracking - PMA Sections, %

Fatig

ue C

rack

ing

- Com

pani

on

Sect

ions

, %

Years for equal cracking?


Fracture Damage AnalysisTensile strain at bottom of HMA layer.Neat sections individually calibrated & used to predict PMA cracking.

( )( )( ) ( ) 854.0291.3

1 1000432.0−−

=

E

CN

t

Mff

ε

HMA Wearing Surface

HMA Base

Granular Base

Subgrade

εt

⎟⎟⎠

⎞⎜⎜⎝

⎛−

+= 69.084.4

beffa

beff

VVV

M


Fatigue Cracks – Neat Vs PMA

0102030405060708090

100

0 20 40 60 80 100

Predicted Fatigue Cracking, %

Mea

sure

d Fa

tigue

Cra

ckin

g, %

Companion Sites Sites with Modified Mixtures Line of Equality


Transverse Cracking – Neat Vs PMA

0.050.0

100.0150.0200.0250.0300.0350.0400.0450.0500.0

0.0 100.0 200.0 300.0 400.0 500.0

Transverse Cracking - PMA Sections, ft.

Tran

sver

se C

rack

ing

- Com

pani

on

Sect

ions

, ft.


Enhanced Performance Based on Damage Analysis

00.5

11.5

22.5

0 10 20 30 40 50

Age, years

Dam

age

Inde

x

Conventional HMA Mixtures PMA Mixtures

Material related distress.


Expected Increase in Service Life, yrsSite Factor Condition Description Added Life

FoundationNon-Expansive 5-10Expansive 2-5Frost Susceptible – Cold Climate 2-5

Water Table & Drainage

Deep 5-10Shallow; Adequate 5-8Shallow; Inadequate 0-2

Existing Pavement Condition

HMAGood 5-10Poor-Extensive Cracking 1-3

PCCGood 3-6Poor-Faulting & Cracking 0-2


Expected Increase in Service Life, yrsSite Factor Condition Description Added LifeClimate; Temp. Fluctuations

Hot Hot Extremes 5-10Mild 2-5Cold Cold Extremes 3-6

Traffic, Truck Volumes

LowIntersections 5-10Thoroughfares 3-6Heavy Loads 5-10

Moderate 5-10High 5-10

S1SP ARA0127-22

Summary Comments


SummaryUse of PMA reduces distress in pavements & overlays

Less Fatigue CrackingFewer Transverse CracksSmaller Ruts

00.20.40.60.8

11.21.41.61.8

2

0 0.2 0.4 0.6 0.8 1 1.2

Rut Depths on PMA Sections, inches

Rut

Dep

ths

on C

ompa

nion

Se

ctio

ns, i

nche

s

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

0.00 20.00 40.00 60.00 80.00

Fatigue Cracking - PMA Sections, %

Fatig

ue C

rack

ing

- Com

pani

on

Sect

ions

, %

0.050.0

100.0150.0200.0250.0300.0350.0400.0450.0500.0

0.0 100.0 200.0 300.0 400.0 500.0

Transverse Cracking - PMA Sections, ft.

Tran

sver

se C

rack

ing

- Com

pani

on

Sect

ions

, ft.


SummaryField & laboratory investigations of PMA

mixes suggest:Enhanced Performance

25 to 100 % increase in service life3 to 10 years increase in service life

Reduced Maintenance ActivitiesCrew SafetyEliminate Traffic Delays


SummaryQuality of Construction –STILL IMPORTANT, IF NOT THE MOST IMPORTANT FACTOR.Many M-E Transfer Functions are stiffness based for binder & mix –OTHER MATERIAL PROPERTIES ARE MORE IMPORTANT.


Thank you for your attention -Any questions?




Finding from Colorado Study

Use of PMA mixes extended the overlay service life over neat HMA mixes by:

3 years – 75 percentile value6 years – 50 percentile value

Documents

Modified Asphalt Binders – Enhancing Pavement Performance. Vo… · Modified Asphalt Binders – Enhancing Pavement Performance Harold L. Von Quintus, ... adopted the P-G specifications