ppa and binder modification - purdue engineering workshop... · 2011-03-01 · effect of hydrated...
TRANSCRIPT
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.
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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.
16
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.
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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.
23
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.
27
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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Thank You
Questions