1

PPA and Binder Modification

John D’Angelo

Office of Pavement Technology

What is the Effect of PPA on binder properties?

• How does PPA react with polymers?

• What is the affect of different crude sources?

• How does Hydrated Lime affect the interaction of the PPA and binder and polymer modification?

2

Evaluation Procedure

• AASHTO M320 Table 1

• AASHTO M320 Table 3

– New High Temperature Grading System using MSCR

• % Recovery MSCR Test

• Elastic Recovery Test

3

AASHTO M320 Table 3 Determination of Jnr

0

5

10

15

20

25

30

0 20 40 60 80 100

Time s

No

rma

lize

d S

tra

in %

γu = Avg. un-recovered

q strain

Jnr = γu / τ

τ = applied stress during creep kPa

Jnr = non-recoverable compliance

0

1

2

3

4

5

6

7

0 2 4 6 8 10 12

time s

Str

ain

%

γr = recovered strain

What is % Recovered Strain

γu = un-recovered strain

γp = Peak strain

% recovery= (γr / γp) X

100

Effect of PPA on High Temp Binder Grade

• Two Crude Sources

– Venezuelan and Saudi Light

• One Level of PPA addition 0.5% by wt of Binder

6

Effect of PPA on High Temp Binder Grade

7

71.6

78

66.7

69.570.1

77.2

65.8

67.9

596061626364656667686970717273747576777879

Venezuelan Venezuelan + .5 PPA Saudi Saudi + .5 PPA

Cont

inuo

us G

rade

Tem

p.

SHRP MSCR

Effect of PPA on High Temp Binder Grade

• PPA Effected Different Crude Sources Differently.

– .5% PPA Increased the grade temp of the Venezuelan 7˚C for both the Table 1 and 3.

– .5% PPA Increased the grade temp of the Saudi Light 2 to 3˚C for both the Table 1 and 3.

8

Effect of PPA on Blending of binders and polymers

• PG 64-22 Saudi Light Base asphalt

• 4 % SBS polymer

– Radial

– Linear

• 0.5% PPA

• 2 blending temperatures

PPA Effects High temp and polymer network, MSCR more distinguishing

Sample

IDContinuous

Grade Polymer AcidTemp Jnr

3.2kPa = 1 ER Temp C% Recovery

3.2kPa

LC 66.7-24.1 0 56.4 5 64C 0

LC 4 75.7-22.3 4% SBS 0 65.1 73.8

70C 19.2

76C 5.96

LC P4 81.2-22.2 4% SBS 0.50% 69.9 93.8

70C 28.4

76C 20.55

LOP 4 76.6-25.2

4% SBSfrom

Concentrate 0 69.1 86

70C 40.3

76C 37.02

LOP 4P 81.6-24.5

4% SBSfrom

Concentrate 0.50% 74.1 91.6

70C 52.05

76C 42.52

Polymer network effects response and temperature effects.

0

100

200

300

400

500

600

700

800

0 2 4 6 8 10

time s

% s

tra

in

LC P4 70C

LOP 4P 70C

LC 4 70C

LOP 4 70C

4 binders same base asphalt all with 4% SBS polymer. 2 with .5% PPA all have different properties.

LC 4LC 4P

LOP 4 LOP 4P

Fluorescence Micro-graphs at 250 magnification

show changes in Morphology

Discreet polymer particles

polymer strands

developing

More uniform dispersion

some bulking

More uniform dispersion almost

cross-linked

Effect of PPA on Blending of binders and polymers

• PPA improved both the High Temperature Grade and the polymer networking in the binders.

• G*/sinδ indicates a larger improvement than MSCR Jnr.

• MSCR % Recovery indicates improved cross-linking with PPA.

13

Effect of PPA on Binder SBS and Cross-linking

• Venezuelan 58-28 Base

– Add 3% linear SBS

– Add .06% Sulfur Cross-linker

– Add .5% PPA

14

Change in MSCR with the addition of Cross-linker and PPA @ 64C

150.01

0.1

1

J nr@

3.2

kPa

-1

Org Blend

Org Blend XL

Org Blend PPA

Org Blend PPA XL

Change in MSCR with the addition of Cross-linker and PPA @ 64C

• The addition of 0.5% PPA to the Venezuelan 58-28 & 3% SBS changed the Jnr from 0.76 to 0.17 a 2 grade improvement

• The addition of 0.5% PPA to the Cross-linked SBS changed the Jnr from 0.99 to 0.06 a 3 grade improvement.

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Change in MSCR % Recovery with the addition of Cross-linker and PPA @64C

17

0

10

20

30

40

50

60

70

80

90

1Org blend Org Blend + XL Org Blend + PPA Org Blend + PPA + XL

MSCR %

Reco

very

Change in MSCR % Recovery with the addition of Cross-linker and PPA @64C

• The addition of 0.5% PPA to the Venezuelan 58-28 & 3% SBS changed the MSCR % Recovery from 30% to 60%

• The addition of 0.5% PPA to the Venezuelan 58-28 & 3% SBS + cross-linker changed the Changed the % Recovery from 30% to over 80%.

• PPA appears to improve the cross-linking of SBS in the binder.

18

Effect of Hydrated Lime on PPA Modified Asphalt

• 64-22 Saudi Light blended with flux to produce a 58-28.

– 1.2 % PPA was added to bring the binder back to a 64-22.

– 20% Hydrated Lime was added to both the 58-28 and the 64-22.

– 20% Hydrated Lime was added to the 58-28 + 1.2% PPA.

• Run complete PG grading and MSCR.19

Effect of Hydrated Lime on PPA Modified Asphalt

• All testing was done with Hydrated Lime in the binder.

• Hydrated Lime has all material smaller than 75 microns, much less than the 250 spec T 315

• 20% Hydrated Lime by weight is approximately 7% by volume. Well below volumes that will affect validity of DSR measurements.

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M320 grading for the different bends Effect of Hydrated Lime on PPA

21

65.259.1

63.470.7

64.1 66.7

-28.4 -26.1 -25.2 -21.7 -29.3 -24.9-34.0-28.0-22.0-16.0-10.0

-4.02.08.0

14.020.026.032.038.044.050.056.062.068.074.0

PPA/HL Modified Binders

Original DSR

RTFO DSR

PAV DSR

BBR S-value

BBR m-value

292 437585 920 415 675

MSCR PG-S M320 Table 3 grading Effect of Hydrated Lime on PPA

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58.462.8 63.3 64.7 65.1

69.5

-28.8-26.1

-29.3-24.9 -24.9

-21.7

-40.0

-30.0

-20.0

-10.0

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

MSCR PG S continuous temp

MSCR 3.2 1/kPa PAV DSR BBR S BBR m

cont

inuo

uste

mp

Effect of Hydrated Lime on PPA Modified Asphalt

• The addition of 1.2% PPA to the Saudi Light 58-28 increased the high temp grade of the binder by 5ºC for both G*/sinδ and Jnr.

• The Hydrated Lime increased the high temp. grade of the binder by 4ºC in both grading systems.

• If the Hydrated Lime increased the 64-22 by 4ºC it should increase the 58-28 with PPA by 4ºC also.

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Effect of Hydrated Lime on PPA Modified Asphalt

• In this case the Hydrated Lime increased the high temp grade only 2.6ºC measured by G*/sinδ and only 1.5ºC measured by Jnr.

• For the Saudi Light it appears the Hydrated Lime is partially neutralizing the stiffening affect of the PPA.

• It is not a complete reversal by a one half to two thirds reversal based on the measuring system.

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Effect of Hydrated Lime on PPA and SBS Modified Binder

• PG 58-28 base asphalt

– Add 3% SBS

– Add .5% PPA and 3% SBS

– Add 20% Hydrated Lime to both the SBS binder and the SBS + PPA binder

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Effect of Hydrated Lime on PPA and SBS Modified Binder. MSCR Jnr @ 64C

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0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

3% SBS 3% SBS + .5% PPA 3% SBS + 20% Lime

3% SBS + .5% PPA + 20% Lime

expect improvement

4H 200C

6H 200C

J nrkP

a-1 @

64C

73.5% 64.0% 82.0% 73.5%

64.0%

Expected Improvement

32.0%

Effect of Hydrated Lime on PPA and SBS Modified Binder. MSCR Jnr @ 64C

• .5% PPA added to the Venezuelan and SBS reduced the Jnr from .94 to .25 just at 2 full grades.

• 20% Hydrated Lime added to the Venezuelan and SBS reduced the Jnr from .94 to .34, 1 ½ grades or a V to an E.

• The PPA and Lime together reduced the Jnrfrom .94 to .17, 2 ½ grades not the expected 3 ½ grades.

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Effect of Hydrated Lime on PPA and SBS Modified Binder. MSCR % Rec.

28

21.5

30.1 29.631.8

25.4

44.3

33.6

41.4

0

5

10

15

20

25

30

35

40

45

50

3% SBS 3% SBS + .5% PPA 3% SBS + 20% Lime 3% SBS + .5% PPA + 20% Lime

MSC

R %

Rec

over

y

4Hr

6Hr

Effect of Hydrated Lime on PPA and SBS Modified Binder. MSCR % Rec.

• The .5% PPA had a significant effect on the MSCR % Recovery increasing it from 25% to 44%. This is likely due to increased stiffening and improved cross-linking

• The Hydrated Lime also increased the % Rec from 25% to 34%. This is likely due to increased stiffening.

• Together no real increase or decrease is seen over just the PPA. Once the polymer is cross-linked it does not appear the lime reduces the effect.

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Conclusions

• PPA does increase the stiffness of asphalt binders in both the old Table 1 and new Table grading system.

– The extent of the stiffening effect is crude source dependant

– For high asphaltene Venezuelan .5% PPA will increase the stiffness one full grade.

– For the lower asphaltene Saudi asphalt 1.2% PPA just makes one full grade stiffening.

30

Conclusions

• PPA improves the properties of SBS modified binders.

– PPA appears to improve the cross-linking of the SBS in the binder improving % Recovery response and amplifying the stiffening effect of the PPA most likely through the improved cross-linking

31

Conclusions

• The addition of Hydrated Lime to PPA modified binders appears to reduce some of the stiffening effect of the PPA.

• The amount of reduction in stiffness varied from 30% to 50%.

• The Hydrated Lime does not appear to reduce the % Recovery of the binder. Once the cross-linking take effect the addition of Lime does not reduce it.

32

Conclusions

• PPA can be used to increase the stiffness of asphalt binders and improve cross-linking and elastic response of polymer modified binder.

• Extreme care must be taken when using PPA in a Mix where Hydrated Lime is used as a filler or anti-stripping agent.

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34

Thank You

Questions