Transcript E* OF AOX-MODIFIED ASPHALT MIXTURES

Development of Antioxidant Treatments
for Asphalt Binders and Mixtures
Alex Apeagyei
Prof Bill Buttlar
Prof Barry Dempsey
November 9, 2005
Department of Civil and Environmental Engineering
University of Illinois at Urbana-Champaign
Outline of Presentation
Introduction
Research Approach
Experimental Design
Analysis of Results
Summary and Conclusions
Recommendations
Introduction: – Purpose of Study
The goal was to develop Antioxidant (AOX)
treatments …
… to reduce oxidative aging in asphalt binders
and mixtures
Problem Statement
The problem of asphalt aging still exists despite
the extensive use of antioxidants:
Issues:
 Sacrificial AOX, get consumed with time
 Extensive degradation after 2-6 years
 Possible environmental concerns
Experimental Plan
 Selection of AOXs:- Eight additives
 Binder testing
 RTFO, PAV
 Dynamic Shear Rheometer (DSR) Test
 Bending Beam Rheometer (BBR) Test
 Mixture testing
 Tests performed on most promising AOX system
 Creep Compliance, Dynamic modulus, Tensile
strength, DC(T) Fracture Energy, Moisture damage
List of AOXs evaluated
1. Irganox 1010
2. Vitamin E (Irganox E201)
3. Irgafos P-EPQ
4. Dilaurylthiodipropionate (DLTDP)
5. Furfural
6. Acryloid B-48N
7. Carbon Black (Raven 790)
8. Hydrated Lime
Evaluation of Aging
 Aging Index (AI) used for evaluating aging
 AI of binders based on SUPERPAVE Parameters
 G*/Sind at 64 ºC
 G*Sind at 25 ºC
AI 
G * / Sind RTFOaged
G * / Sind unaged
 AI of mixtures based on
 Creep Compliance, E*, Tensile Strength, Fracture
Energy
Evaluation of Binder Results
 Comparison of binder AI after RTFO
2.4
Control
Aging Index
2.2
2.0
AOX-Modified
1.8
1.6
1.4
1.2
1.0
Specimen
Aging Index: G*Sind at 25 ºC after PAV
Aging Index
7.0
S16
5.0
S14
S13
3.0
1.0
Sample
S13 – DLTDP + Furfural + Catalyst
S14 – Vitamin E + Furfural + catalyst
S16 - Control
Effect of AOXs on G*Sind after PAV
Stiffness at 25 C (MPa)
Control
6.0
S16
4.0
S13
2.0
0.0
Sample
S14
Effect of AOXs on Creep Stiffness after PAV
Stiffness at -12 C (MPa)
Control
160
S16
120
S13
80
40
0
Sample
S14
Effect of AOXs on m-value at after PAV
0.50
Control
m-value
S13
0.45
S16
S14
0.40
0.35
Sample
Effects of AOX on long-term binder aging
Control
Improvement 20%
10.0
Aging Index
AOX-Mod
8.0
6.0
Improvement 40%
4.0
2.0
0.0
25 ºC
64 ºC
Selection of most promising AOX
 S13 contains DLTDP/Furfural + catalyst
 S13 is most preferred AOX treatment
 Sample S13 will be labeled AOX-Modified
 Asphalt concrete mixtures limited to S13
Asphalt Mixture Fabrication
 Materials:
 Limestone aggregates (9.5 mm Nom. Max)
 PG 64-22 binder (Control)
 AOX-Modified PG 64-22 binder
 Mixture Aging
 Short-term oven aging (135 ºC for 2 hours, STOA-2h)
 Long-term oven aging (135 ºC for 8 hours, LTOA-8h)
Mixture Tests Performed
1. Creep Compliance
2. Dynamic Modulus E*
3. Indirect Tensile Strength
4. DC(T) Fracture Test (Wagoner et al. 2004)
5. Moisture Susceptibility
Creep Compliance master curve (Tref = -20 C)
Control-STOA-2h: m=0.47
Modified-LTOA-8h: m=0.3813
Modified-STOA-2h: m=0.4021
Control-LTOA-8h: m=0.3597
Creep Compliance (1/GPa)
0.45
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
1
100
10000
Reduced Time (sec)
1000000
Effect of aging on creep compliance
Retained Creep Compliance
1.0
0.8
0.6
AOX-Modified
Control
0.4
0.2
0.0
1
1000
Reduced Time (sec)
1000000
E* master curve (Tref = 20 ºC)
Dynamic Modulus E* (MPa)
25000
Tref = 20 0C
20000
Mod-LTOA-8h
Mod-STOA-2h
Contr_LTOA-8h
Contr-STOA-2h
15000
10000
5000
0
0.001
0.1
10
1000
Reduced Frequency (Hz)
100000 1E+07
Effect of aging on dynamic modulus E*
Aging Index
2.2
1.8
AOX-Modified
Control
1.4
1.0
0.001
0.1
10
1000
100000
Reduced Frequency (Hz)
1E+07
DC(T) Fracture Testing
DC(T) Specimen
Test Setup
Retained Fracture Energy
Effect of Aging on Fracture Energy
1.6
1.2
Control
AOX-Mod
0.8
0.4
0.0
0 ºC
-10 ºC
Moisture Susceptibility
To investigate the moisture damage
potential of AOX-Modified Asphalt Mix
Tests performed
AASHTO T283 [Tensile Strength Ratio, TSR]
DC(T ) [Fracture Energy Ratio, FER]
Aggregates used:
 Limestone
Limestone Results Summary
Moisture Damage ratio
1.6
1.2
Control
AOX-Mod
0.8
0.4
0.0
TSR
FER
Limestone mixtures: Visual rating
TSR  0.74
TSR  0.43
Conclusion
The AOX treatments evaluated during this
study appear to cause significant reduction in
age-hardening of the PG 64-22 asphalt used
Recommendations
 Evaluate AOXs using different asphalt sources
 Full-scale production of the AOX-Modified
 Construction of Full-scale pavement sections
 Accelerated testing
 Long-term performance evaluation
Acknowledgements
 Research conducted at ATREL and was
supported by the Center of Excellence for
Airport Technology funded by the FAA
 Special thanks to:
 Prof Barry Dempsey – Director of Research
 Prof Bill Buttlar – Advisor
End of Presentation
Thank You!