Oxidative aging and rheological performance of modified asphalt binder
1. Evaluation of Thermal Oxidative Aging Effect on the
Rheological Performance of Modified Asphalt Binders
Thesis Defense
Cheng Zhu
Advisor: Prof. Peter E. Sebaaly, Ph.D. , P.E.
Nov. 17th 2015
www.wrsc.unr.edu 11/17/2015
1
2. Outline
o Background of Asphalt Binder Aging
o Objective of Study
o Experimental Plan
Aging Materials
Aging Conditions
Binder Test Methods
o Analysis Methodologies
oTest Results
o Field Asphalt Aging Prediction
o Conclusion and Future Consideration
2
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3. Background of Asphalt Binder Aging
• Generally, asphalt binder becomes more brittle and stiffer
under the effect of the oxidative aging condition.
• Therefore, the tensile stress relaxation capability
dramatically dropped that the aging induced cracking
occurred.
• The asphalt binder aging mechanism has been studied
for more than one century ( Hubbard, et al. 1913).
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4. Background of Asphalt Binder Aging
• Binder Aging Researches conducted mainly focus on:
Chemistry issues- material reaction with the ubiquitous oxygen.
Physical properties- rheological performance field pavement
performance.
• Asphalt binder has very complex compositions which
makes a challenge to characterize the oxidative aging
mechanism at a molecular level.
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5. Background of Asphalt Binder Aging
• Some finding
- Generally, dividing the asphalt binder to several fractions by the
similar molecular weight or properties, i.e. SARA. (Robert, 1969)
- With the asphalt binder aging, the nonpolar fractions, such as
aromatics and saturates, reacted with the ubiquitous oxygen, then
produced higher molecular and polar fractions- asphaltenes. This
process has several different steps.
- Usually, the final products-carbonyl and sulfoxide were used to
identify the asphalt binder aging reaction (Arrhenius kinetic).
- The advanced microscopic methodologies are implemented to
characterize the chemical component change during the aging.
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6. Background of Asphalt Binder Aging
• Some finding
- Master curve is a good tool to characterize the asphalt binder mechanical
properties, shear modulus-G*, viscosity-η, phase angle.
- SHRP project report A-368: Binder Characterization and Evaluation, volume 2:
Chemistry. (1993)
- NCHRP project 9-10: Superpave Protocols for Modified Asphalt Binders.
- NCHRP project 9-52: Short-Term Laboratory Conditioning of Asphalt Mixtures.
- NCHRP project 9-54: Long-term Aging of Asphalt Mixtures.
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7. Background of Asphalt Binder Aging
• Some References
- Petersen, J.C., 2009. A Review of the Fundamentals of Asphalt Oxidation:
Chemical, Physicochemical, Physical Property, and Durability Relationships, Trans
Res Circular, E-C140, Transportation Research Board, Washington, DC.
- McNally, Tony, ed. Polymer Modified Bitumen: Properties and Characterization.
Elsevier, 2011.-Chapter 9
- Huang, Shin-Che, and Hervé Di Benedetto, eds. Advances in Asphalt Materials:
Road and Pavement Construction. Woodhead Publishing, 2015.- Chapter 9
- Several Texas DOT Projects reports- Dr. Glover’s group conducted, such as:
FHWA/TX-05/1872; FHWA/TX-05/0-4468; FHWA/TX-08/0-6009 etc.
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8. Background of Asphalt Binder Aging
However, most of the researches finished were based on
the neat asphalt binder, and the study of modified asphalt
binder aging mechanism was limited.
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Example of the benefit of SBS, TR-modified asphalt binder (Courtesy of Dr. Glover)
9. Objective of Study
• Base on the previous asphalt binder aging research
finished at UNR under ARC contracts, this study was
extended to evaluate:
- The kinetic reaction of different modified asphalt binders
under the oxidative aging conditions.
- The rheological performance change caused by the
thermal oxidative aging effect.
- The hardening susceptibility of the objective asphalt
binders.
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10. Experimental Plan
• Materials (14 different asphalt binders)
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Binder ID Base A Base B - - Base C Base D
Tire-rubber - B_TR - - - -
Additional
component
(X, Y, Z)
- B_TR_X B_TR_Y B_TR_Z - -
SBS A_PM B_TR_X_PM B_TR_Y_PM B_TR_Z_HPM C_PM D_HPM
11. Experimental Plan
• Aging Conditions (air forced draft ovens)
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Aging
Temperature
50℃ 60℃ 85℃
Aging Duration
4, 8, 15, 30, 60,
120, 180, 240 days
2, 4, 8, 15, 30, 60,
100, 160 days
0.5, 1, 2, 4, 8, 15,
25, 40 days
13. Experimental Plan
• Test Condition-FTIR-ATR
• Fourier Transform Infrared Spectroscopy (FTIR)-Attenuated Total
Reflectance (ATR) :
Each asphalt sample test 2 replicates and each for 3 measurements.
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Nicolet 6700
14. Experimental Plan
• Test Condition-FTIR-ATR
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AASHTO T302-15 Standard Method of Test for Polymer Content of
polymer-modified Emulsified Asphalt Residue and Asphalt Binders.
16. Experimental Plan
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Oxidative Aging
Due to the tire rubber (black), the absorption ratio
is so high that the right part jumps up, use the base
line correction function to make it flat.
17. Experimental Plan
• Test Condition-DSR
• Frequency Sweep Mode-
-8 mm dia. Spindle, 2 mm gap, 1% shear strain, 0.1
rad/s to 100 rad/s with 6 points/decades (19 data
points per isotherm).
-25 mm dia. Spindle, 1 mm gap for 52-80 ℃ test,
0.5 mm gap for above 85 ℃ test, both run 1%
shear strain, 0.01 to 100 rad/s, 2.25
points/decades (10 data points per isotherm).
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19. Analysis Methodologies
• Analysis Method-Rheology-Master Curve Development
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10
1
10
2
10
3
10
4
| *|
10
-1
10
0
10
1
10
2
10
3
10
4
10
5
Pa
G'
G''
0.001 0.01 0.1 1 10 100Hz
Frequency f
Text
FS
Anton Paar GmbH
PG64-28_NV_85C_40d_85-95-100_A 1
PP25/PE-SN26830; [d=0.5 mm]
| *| Complex Viscosity
G' Storage Modulus
G'' Loss Modulus
PG64-28_NV_85C_40d_85-95-100_A 2
PP25/PE-SN26830; [d=0.5 mm]
| *| Complex Viscosity
G' Storage Modulus
G'' Loss Modulus
PG64-28_NV_85C_40d_85-95-100_A 3
PP25/PE-SN26830; [d=0.5 mm]
| *| Complex Viscosity
G' Storage Modulus
G'' Loss Modulus
DSR Measures – Example PG64-28 (SBS)
20. Test Results Analysis
• Master Curve Shifting Functions (more than 20)
Follow Time Temperature Superposition Principle
- The frequency sweep test LVE region.
- TTSP-exact isothermal curve, same shift factor, aT
has a reasonable form, i.e. Arrhenius, WLF, Kaelble.
- Thermorheologically Simple same temperature
dependence. (a very complex topic-not simple)
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24. RHEA Software Shifting Process-3
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Cautious of extrapolation
Arms of Prony Series
25. Master Curve for the Modified asphalt binders
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Binder slippage
26. Master Curve for the Modified asphalt binders
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Phase angle
rotation
Phase angle
rotation
27. Master Curve for the Modified asphalt binders
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Platform-phase
transition
Platform-phase
transition
28. Master Curve for the Modified asphalt binders
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Modified asphalt binder
has more complicate
amorphous phase than
neat binder
30. Rheological Indices
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Crossover Modulus G*c -Analogous to rheological index, R
1.00E-02
1.00E-01
1.00E+00
1.00E+01
1.00E+02
1.00E+03
1.00E+04
1.00E+05
1.00E+06
1.00E+07
1.00E+08
1.00E-03 1.00E-01 1.00E+01 1.00E+03 1.00E+05 1.00E+07 1.00E+09
G',G''(Pa)
Frequency (rad/s)
Base A-orig-Loss Modulus
Base A-orig-Storage Modulus
fc
G*c, fc when the
phase angle
at 45º
R=G*g-G*c
31. Rheological Indices
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DSR Function 𝐃𝐒𝐑𝐅𝐧 =
𝐆′
𝛈′
𝐆′
(Dr. Glover)
y = 9E+13x-3.567
R² = 0.9945
1.E+02
1.E+03
1.E+04
1.E+05
1.E+06
1.E+07
100 300 500 700 900 1100 1300 1500
G'(15°C,0.005rad/s)
η'/G' (s) (15°C, 0.005 rad/s)
Base A DSR function
32. Rheological Indices
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Glover-Rowe Parameter G-R =
𝑮∗ 𝝎 𝒄𝒐𝒔 𝟐 𝜹
𝒔𝒊𝒏 𝜹
1.00E+02
1.00E+03
1.00E+04
1.00E+05
1.00E+06
1.00E+07
1.00E+08
1.00E+09
0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00 90.00
|G*|(Pa)(15°C0.005rad/s)
Phase Angle (°)
Base A Black Space Diagram
Base A G-R
G-R at 180 kPa
G-R at 450 kPa
G*/sin(phase angle)≥2.2kpa
G*sin(phase angle)≤5000kpa
85°C, 40d
85°C, 25d
33. Rheological Indices-Conditions
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Rheological Indices Applicable Conditions
Name Symbol
Temperature
(°C)
Frequency
(rad/s)
Notes
Low Shear
Viscosity
LSV 60 0.001 Has also been measured at 0.1 rad/s
DSR Function DSRFun 15 0.005 Can be shifted from 10 rad/s at 44.7°C
Glover-Rowe
Parameter
G-R 15 0.005 or Var.
Also evaluated at 20°C, potential for
representative Int. temps.
Crossover
Modulus
G*c 25 fc
Corresponds to a phase angle of 45°
Crossover
Frequency
fc 25
34. Kinetic Aging Parameters
• Arrhenius Equation-
-Where, A = the frequency factor,
P = the oxygen pressure,
α= the reaction order,
E =the activation energy (kJ/mol),
R=the gas constant (8.314 J.mol/°K),
T= the absolute temperature.
It is a formula for the temperature dependence of
reaction rates.
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RTE
CA eAP
t
CA
r /
37. Kinetic Aging Parameters-CA fitting Model
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0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0 50 100 150 200 250
CA
Time (day)
B_TR_X
Reg fitting-85℃ Reg fitting-60℃ Reg fitting-50℃
85°C 60°C 50°C
Fast Rate Reaction
Constant Rate Reaction
kc
tk
CAtkeMCA f
tan
*
*)1(
38. Hardening Susceptibility
• Generally, there is a good correlation between the
rheological indexes and the carbonyl area
parameter-exponential function.
or
ln(𝑅𝐼) = 𝐻𝑆 ∗ 𝐶𝐴 + 𝑚
RI-Rheological Indexes.
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𝑅𝐼 = 𝑒 𝐻𝑆∗𝐶𝐴
𝑒 𝑚
39. Hardening Susceptibility-Examples
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y = 7.5245e11.109x
R² = 0.9513
y = 327.4e7.9403x
R² = 0.9247
1.E+01
1.E+02
1.E+03
1.E+04
1.E+05
1.E+06
1.E+07
0.000 0.200 0.400 0.600 0.800 1.000
LSV(Pa.s,60°C,0.001rad/s)
Carbonyl Area (arb. unit)
Base A
A_PM
Expon. (Base
A)
Expon. (A_PM)
y = 54503e-5.603x
R² = 0.9701
y = 27635e-4.653x
R² = 0.9126
1.E+00
1.E+01
1.E+02
1.E+03
1.E+04
1.E+05
0.000 0.200 0.400 0.600 0.800 1.000
G*c(kPa,25°C)
Carbonyl Area (arb. unit)
Base A
A_PM
Expon. (Base
A)
Expon. (A_PM)
y = 0.0037e17.172x
R² = 0.9746
y = 0.4427e10.155x
R² = 0.9652
1.E-02
1.E-01
1.E+00
1.E+01
1.E+02
1.E+03
1.E+04
0.000 0.200 0.400 0.600 0.800 1.000
G-R(kPa,15°C,0.005rad/s)
Carbonyl Area (arb. unit)
Base A
A_PM
Expon. (Base
A)
Expon. (A_PM) y = 0.0163e17.418x
R² = 0.9781
y = 2.2151e10.154x
R² = 0.9653
1.E-02
1.E-01
1.E+00
1.E+01
1.E+02
1.E+03
1.E+04
0.000 0.200 0.400 0.600 0.800 1.000
DSRfunc.(pa/s,15°C,0.005rad/s)
Carbonyl Area (arb. unit)
Base A
A_PM
Expon. (Base
A)
Expon. (A_PM)
40. Test Results Analysis-Kinetic Parameters
Asphalt
Binder
Modifier
Influence of Modification on
kf Eaf kc Eac
A SBS ↓ ↓ ↓ ↓
C SBS ↓ ↓ ↓ ↑
D SBS ↓ ↑ ↓ ↑
B TR ↓ ↓ ↓ ↑
B_TR_X SBS ↑ ↑ ↑ ↓
B_TR_Y SBS ↑ ↑ ↓ ↓
B_TR_Z SBS ↑ ↓ ↑ ↓
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41. Test Results Analysis-LSV vs CA
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1.E+01
1.E+02
1.E+03
1.E+04
1.E+05
1.E+06
1.E+07
0.000 0.200 0.400 0.600 0.800 1.000
LSV(Pa.s,60°C,0.001rad/s)
Carbonyl Area (arb. unit)
Base A
A_PM
Base C
C_PM
Base D
D_HMP
Expon. (Base A)
Expon. (A_PM)
Expon. (Base C)
Expon. (C_PM)
Expon. (Base D)
Expon. (D_HMP)
42. Test Results Analysis-LSV vs CA
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1.E+01
1.E+02
1.E+03
1.E+04
1.E+05
1.E+06
1.E+07
0.000 0.200 0.400 0.600 0.800 1.000
LSV(Pa.s,60°C,0.001rad/s)
Carbonyl Area (arb. unit)
Base B
B_TR
B_TR_X
B_TR_X_PM
B_TR_Y
B_TR_Y_PM
B_TR_Z
B_TR_Z_HPM
Expon. (Base B)
Expon. (B_TR)
Expon. (B_TR_X)
Expon. (B_TR_X_PM)
Expon. (B_TR_Y)
Expon. (B_TR_Y_PM)
Expon. (B_TR_Z)
Expon. (B_TR_Z_HPM)
43. Test Results Analysis-G*c vs CA
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1.E+00
1.E+01
1.E+02
1.E+03
1.E+04
1.E+05
0.000 0.200 0.400 0.600 0.800 1.000
G*c(kPa,25°C)
Carbonyl Area (arb. unit)
Base A
A_PM
Base C
C_PM
Base D
D_HMP
Expon. (Base A)
Expon. (A_PM)
Expon. (Base C)
Expon. (C_PM)
Expon. (Base D)
Expon. (D_HMP)
44. Test Results Analysis-G*c vs CA
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1.E+02
1.E+03
1.E+04
1.E+05
0.000 0.200 0.400 0.600 0.800 1.000
G*c(kPa,25°C)
Carbonyl Area (arb.unit)
Base B
B_TR
B_TR_X
B_TR_X_PM
B_TR_Y
B_TR_Y_PM
B_TR_Z
B_TR_Z_HPM
Expon. (Base B)
Expon. (B_TR)
Expon. (B_TR_X)
Expon. (B_TR_X_PM)
Expon. (B_TR_Y)
Expon. (B_TR_Y_PM)
Expon. (B_TR_Z)
Expon. (B_TR_Z_HPM)
45. Test Results Analysis-G-R vs CA
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1.E-02
1.E-01
1.E+00
1.E+01
1.E+02
1.E+03
1.E+04
0.000 0.200 0.400 0.600 0.800 1.000
G-R(kPa,15°C,0.005rad/s)
Carbonyl Area (arb. unit)
Base A
A_PM
Base C
C_PM
Base D
D_HMP
Expon. (Base A)
Expon. (A_PM)
Expon. (Base C)
Expon. (C_PM)
Expon. (Base D)
Expon. (D_HMP)
46. Test Results Analysis-G-R vs CA
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1.E-02
1.E-01
1.E+00
1.E+01
1.E+02
1.E+03
1.E+04
0.000 0.200 0.400 0.600 0.800 1.000
G-R(kPa,15°C,0.005rad/s)
Carbonyl Area (arb. unit)
Base B
B_TR
B_TR_X
B_TR_X_PM
B_TR_Y
B_TR_Y_PM
B_TR_Z
B_TR_Z_HPM
Expon. (Base B)
Expon. (B_TR)
Expon. (B_TR_X)
Expon. (B_TR_X_PM)
Expon. (B_TR_Y)
Expon. (B_TR_Y_PM)
Expon. (B_TR_Z)
Expon. (B_TR_Z_HPM)
54. Field Asphalt CA Prediction
• CA Prediction Procedure
Preparing Climate Data-TEMPS input file
Run TEMPS Output file-Pavement Temperature
Using Dr. Alavi’s pavementaging.m Matlab code to
calculate the CA at different location, different time and
different asphalt binder film thickness.
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55. Field Asphalt CA Prediction
• Pavement Structure
(Thickness: 0.15 m HMA+0.35 m Gravel Base)
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Material Parameters HMA Gavel Stone Soil
Specific Heat Capacity (J/kg°K) 920 850 800
Conductivity (W/m°K) 1 0.75 1
Density (Kg/m^3) 2250 2100 2000
56. Field Asphalt CA Prediction
• Climate Data
http://gis.ncdc.noaa.gov/map/
http://rredc.nrel.gov/solar/old_data/nsrdb/
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Air Temperature, Wind speed-2010
Solar Radiation
57. Field Asphalt CA Prediction
• TEMPS
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User friendly software
58. Field Asphalt CA Prediction
• Input data of TEMPS
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-20
-10
0
10
20
30
40
50
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
AirTemperature(℃)
Time (hour)
Air Temperature
Reno Air Temperature
Phoenix Air Temperature
Glasgow Air Temperature
59. Field Asphalt CA Prediction
• Input data of TEMPS
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-15
-10
-5
0
5
10
15
20
25
0 200 400 600 800
AirTemperature(℃)
Time (hour)
Air Temperature-January
Reno Air
Temperature
Phoenix Air
Temperature
Glasgow Air
Temperature
60. Field Asphalt CA Prediction
• Output files of TEMPS-Examples
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-6
-4
-2
0
2
4
6
8
10
0 120 240 360 480 600 720 840
Temperature(℃)
Time (hour)
Pav. Temperature-January
Reno Air Temperature
Reno Pav. 0.01m depth
Temperature
Reno Pav. 0.07m depth
Temperature
Reno Pav. 0.15m Depth
Temperature
61. Field Asphalt CA Prediction
• Pavementaging.m Matlab Calculation
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62. Field Asphalt CA Prediction-Results
• Reno-0.01m
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0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 50000 100000 150000 200000
CarbonylArea(Arb.unit)
Time (hour)
Reno-0.01 m depth film surface
A_PM
B_TR_X_PM
B_TR_X
B_TR_Y_PM
B_TR_Y
B_TR_Z_HPM
B_TR_Z
B_TR
Base A
Base B
Base C
Base D
C_PM
D_HPM
o.58
63. Field Asphalt CA Prediction-Results
• Reno-0.07m
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0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 50000 100000 150000 200000
CarbonylArea(Arb.unit)
Time (hour)
Reno-0.07 m depth film surface
A_PM
B_TR_X_PM
B_TR_X
B_TR_Y_PM
B_TR_Y
B_TR_Z_HPM
B_TR_Z
B_TR
Base A
Base B
Base C
Base D
C_PM
D_HPM
o.53
64. Field Asphalt CA Prediction-Results
• Reno-0.15m
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0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 50000 100000 150000 200000
CarbonylArea(Arb.unit)
Time (hour)
Reno-0.15 m depth film surface
A_PM
B_TR_X_PM
B_TR_X
B_TR_Y_PM
B_TR_Y
B_TR_Z_HPM
B_TR_Z
B_TR
Base A
Base B
Base C
Base D
C_PM
D_HPM
o.49
65. Field Asphalt CA Prediction-Results
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0.34115
0.3412
0.34125
0.3413
0.34135
0.3414
0.34145
0 24000 48000 72000 96000 120000 144000 168000 192000
CarbonylArea(abs.unit)
Time(hour)
Reno Base B CA Field Prediction
0.01m depth film surface
0.07m depth film surface
0.15m depth film surface
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0 24000 48000 72000 96000 120000 144000 168000 192000
CarbonylArea(abs.unit)
Time(hour)
Reno B_TR CA Field Prediction
0.01m depth film surface
0.07m depth film surface
0.15m depth film surface
0.1
0.12
0.14
0.16
0.18
0.2
0.22
0.24
0.26
0.28
0 24000 48000 72000 96000 120000 144000 168000 192000
CarbonylArea(abs.unit)
Time(hour)
Reno B_TR_Z CA Field Prediction
0.01m depth film surface
0.07m depth film surface
0.15m depth film surface
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0 24000 48000 72000 96000 120000 144000 168000 192000
CarbonylArea(abs.unit)
Time(hour)
Reno B_TR_Z_HPM CA Field Prediction
0.01m depth film surface
0.07m depth film surface
0.15m depth film surface
66. Field Asphalt CA Prediction-Results
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0.3411
0.3412
0.3413
0.3414
0.3415
0.3416
0.3417
0.3418
0.3419
0.342
0 24000 48000 72000 96000 120000 144000 168000 192000
CarbonylArea(abs.unit)
Time(hour)
Base B CA Field Prediction
Reno-0.01m depth film surface
Phoenix-0.01m depth film surface
Glasgow 0.01m depth film surface
0
0.1
0.2
0.3
0.4
0.5
0.6
0 24000 48000 72000 96000 120000 144000 168000 192000
CarbonylArea(abs.unit)
Time(hour)
B_TR_Z CA Field Prediction
Reno-0.01m depth film surface
Phoenix-0.01m depth film surface
Glasgow 0.01m depth film surface
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0 24000 48000 72000 96000 120000 144000 168000 192000
CarbonylArea(abs.unit)
Time(hour)
B_TR CA Field Prediction
Reno-0.01m depth film surface
Phoenix-0.01m depth film surface
Glasgow 0.01m depth film surface
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 24000 48000 72000 96000 120000 144000 168000 192000
CarbonylArea(abs.unit)
Time(hour)
B_TR_Z_HPM CA Field Prediction
Reno-0.01m depth film surface
Phoenix-0.01m depth film surface
Glasgow 0.01m depth film surface
67. Conclusion and Further Consideration
• Conclusion
Temperature and aging duration played an important role on the asphalt
binder aging hardening, this conclusion was justified by the multi linear
regression analysis.
The asphalt binder aging rate increased with increasing temperature,
carbonyl area is a good parameter to evaluate the oxidative aging extent.
TR reduced the asphalt binders’ fast rate and constant rate reaction, X, Y, Z
asphalt components had modest variation for the fast rate and increased
the constant rate; the SBS modifiers had different direction effect on these
two parameters.
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68. Conclusion and Further Consideration
• Conclusion
With the SBS modification, both of the hardening susceptibility of the
rheological indexes-LSV and G-R decreased compared with the
corresponding base binder. The TR increased the hardening susceptibility
of all the rheological indexes. While for the G*c, SBS increases the slope of
the most modified asphalt binders except A and B_TR_X series binders.
The temperature variation of the pavement structure decreased with the
increasing pavement depth, the predicted CA value range for all the asphalt
binders decreased when the evaluated pavement depth was increasing.
The oxygen diffusion effect on the asphalt binder film aging was highly
binder resource dependent.
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69. Conclusion and Further Consideration
• Further Consideration
Other microscopic analysis tools, such as NMR, AFM, can be used to
compensate the FTIR to get more chemical information for the binder
aging.
The related asphalt mixture aging and real field pavement aging are needed
to investigate the correlation between the laboratory binder aging and field
asphalt binder aging.
How to minimize the field asphalt pavement aging rate is a good extension
for the future study.
More related asphalt binder aging researches or projects are needed to
study the asphalt binder aging oxidative aging mechanism.
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70. Acknowledgement
• Thank you to Dr. Sebaaly, Dr. Hajj, Dr. Morian, and Dr. Lin for their
consistent supporting, teaching, and advising.
• Thanks to Dr. John Hellgeth of Applied Materials Solutions, LLC for
his assistance on the FTIR measurements.
• Thanks to all of my colleagues at UNR pavement program- Dario,
Farzan, Hadi, Jay, Jhony, Luis, Mohamed, Nick, Piratheepan, Sara,
Sendeep, and Victor for their help and friendship.
• I Love Asphalt
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