WRI Research Related to the Optimal Timing of Preventive Maintenance for Addressing

Environmental Aging

Kickoff Meeting

Fred TurnerWestern Research Institute

MnROAD Research FacilityJuly 23, 2008

2

Relevant Research Contracts

Fundamental Properties of Asphalts and Modified Asphalts III, Federal Highway Administration

Asphalt Surface Aging Prediction (ASAP) System, Research and Innovative Technology Administration

• Asphalt Research Consortium, Federal Highway Administration (Aging element, F1c, being conducted by TAMU)

3

FPIII Aging Research

• Study aging in laboratory and field conditions

• Develop testing methods for analyzing aging

• Compare results with the Global Aging System as implemented in the MEPDG

4

Techniques Developed

• Micro extraction with FTIR analysis• Photoacoustic FTIR for surface analyses• Small scale DSR methodology for full range

modulus and relaxation rheology (in progress)• Carbonyl index• Non-carbonyl FTIR-G* correlations• Spectral correlation software

5

Aging at the Arizona Validation Site

6

Arizona Validation Site

Farrar, M. J., P. M. Harnsberger, K. P. Thomas, W. Wiser. Evaluation of Oxidation in Asphalt Pavement Test Sections after Four Years of Service. Proceedings of the International Conference on Perpetual Pavement, September, 2006, Columbus, Ohio.

Constructed Nov. 2001Shoulder cored Nov. 2005

2 – 63 mm lifts, 19-mm NMS dense graded aggregate, 4.7% AC)

7Carbonyl Content, Absorbance Units

0.0 0.1 0.2 0.3 0.4

G*,

kPa,

60°

C, 1

0 ra

d/s

1

10

100

1000

80°C, Dry 60°C, Dry80°C, Moist 60°C, MoistAZ1-1

Relationship between carbonyl content and complex modulus of asphalts

Asphalt Hardening: Laboratory and Field Aging

gel

sol

8

1

2

3

45

67

8

9

0.006

0.011

0.016

0.021

0.026

0.031

0 10 20 30 40 50 60Depth (mm)C

arbo

nyl I

ndex

(A17

00/A

2900

)Arizona Site Aging Profile

Carbonyl Gradient AZ1-1

G* GradientLog G* vs. C=O

E* Gradient

Linear relationship

HirschModel

9

Infrared Spectra From Each Layer

Spectra normalized to CH3 umbrella bending mode at 1376 cm-1

Carbonyl indexSulfoxide indexAromaticity indexOther indexes

Functional groupdepth gradients

AZ1-3b core

10

G* gradient - Arizona validation site at year four

Calibration curve

11

Carbonyl Index

Wavenumber, cm3100

Abs

orba

nce

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.03000 2900 2800

-1

Abs

orba

nce

0.20

0.16

0.12

0.08

0.04

0.001800 1600 1400 1200 1000 800 600

Wavenumber, cm-1

A

Carbonyl Index (CI) =

2900

A1700

A2900

A1700

12

Carbonyl Index (8 asphalts)

13

ASAP Project

• Develop and demonstrate ruggedized FTIR instrumentation, data acquisition system, and data processing procedures to predict and monitor the surface embrittlement of asphalt pavements caused by aging

14

Techniques Applied

• Micro extraction with FTIR analysis• Photoacoustic FTIR for surface analyses• Carbonyl index• Non-carbonyl FTIR-G* correlations

15

Project Elements

Laboratory (WRI)

• Validate spectroscopy-rheology correlation• Find non-carbonyl relationship for airborne applications

• Prepare samples for calibrating ruggedized FTIR system• Unaged, RTFO-aged, RTFO/PAV-aged, field samples

• Develop procedures for handling real-world analyses: • Asphalt content < 100%, • Aggregate infrared absorption, contaminants• Carbonyl indexing• Aggregate and contaminant subtraction techniques

16

Project Elements

Development of FTIR system (Innova, PLX, SimWright)

• Design, construct, and test a vehicle-mounted ruggedized FTIR system

• Demonstrate the technology in the field using a van-mounted, non-contact system

• Determine the effective limits for low-altitude airborne deployment

17

Age-Related Change at Surface

Observations and Assumptions

• HMA pavements oxidize most rapidly at their top surfaces.

• The oxidized binder at the surface has a much higher stiffness than the bulk binder.

• The surface stiffness or complex modulus at lower ambient temperatures will approach the glassy modulus of the binder (~ 109 Pa).

• Pavement damage begins under traffic load when the surface complex modulus of the binder reaches some fraction of the glassy modulus at current use temperature.

Az1-1 4-yr viscosity profile

Binder Viscosity, P

0 2e+5 4e+5 6e+5 8e+5

0 2e+5 4e+5 6e+5 8e+5

Dep

th, i

nche

s

0

1

2

3

4

5

18

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

600800100012001400160018002000

Wave Number, cm-1

Abs

orba

nce

AAB-1 neat

AAB-1 RTFO

AAB-1 PAV 100°C 20hrs

AAB-1 PAV 80°C 480hrs

Carbonyl

1150 - 1250 cm-1 RegionSolvent

WRI/FHWA

Infrared Spectra Changes w/ Aging

19

0.0

0.5

1.0

1.5

2.0

2.5

3.0

600800100012001400160018002000

Wave Number, cm-1

Abs

orba

nce

Surface

0.1"

0.5"

1"

Pavement DepthWRI / FHWA

Infrared Spectra Changes w/ Depth

20

G* Correlations With Carbonyl Content For AAB-1

AAB-1

y = 2.88E+03e1.63E+01x

R2 = 9.70E-01

y = 1.12E+06e9.54E+00x

R2 = 9.24E-01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

1.E+08

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35

Carbonyl Content (1700 cm-1), au

Shea

r M

odul

us, G

*, a

t 10

rad/

s

25°C unaged25°C RTFO

25°C PAV at 60°C25°C PAV at 80°C25°C PAV at 100°60°C unaged

60°C RTFO60°C PAV at 60°C60°C PAV at 80°C

60°C PAV at 100°C

21

Analysis of Infrared Spectra for Correlating Regions

Log(G*) at 60°C, 10 Rad/s

0.0

0.2

0.4

0.6

0.8

1.0

600800100012001400160018002000

Wave Number

R-S

quar

ed fo

r Asp

halt

AA

M-1

Cor

rela

tion

AAM-1

22

Comparison of Absorbances for Laboratory Sample AAM-1

AAM-1

y = 0.3539x + 0.2358R2 = 0.9662

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0 0.1 0.2 0.3 0.4 0.5 0.6

IR Absorbance at 1703 cm-1

IR A

bsor

banc

e at

121

2 cm

-1

23

Relationship Between Absorbance at 1212 cm-1 and G*

y = 9.3037x + 1.153R2 = 0.9629

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6

Absorbance at 1212cm-1

Log

G*

AAM-1

24

G* Correlation Using Absorbance at 1212 cm-1

y = 0.9974xR2 = 0.997

100

1000

10000

100000

1000000

100 1000 10000 100000 1000000

G*, measured 60°C, 10rad/s

G*,

fit

Four asphalts, ten aging conditions

25

PA spectra changes on oxidation of AAD-1

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600.00.03

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.42

cm-1

PA Int

ensit

y (a

rbitr

ay u

nits)

(a) Blue: Unaged. Green: RTFO only. Black: RTFO/PAV 20hours. Brown: RTFO/PAV 144 hours. Pink: RTFO/PAV 240 hours. Red: RTFO/PAV 480 hours. OPD velocity 0.5 cm/sec, 512 co-added scans, gain (4).

26

Photoacoustic spectra – Arizona surface samples from AZ1-3b

AZ1-3b core

Small (approx. 4 mm wide) samples removedfrom the surface

512 co-added scans

27

PA Spectra of Aggregates

28

What is Needed?

• Validation sites for evaluating concepts and instrumentation• Multiple asphalt sources and grades• Multiple surface treatments• Save original materials

• Periodic distress surveys and coring

• High-resolution age profiling in cores

29

WRI Contribution

• Age profiling in cores using micro extraction, photoacoustic techniques

• Field analyses with ASAP System

• Other specialized testing?

31

AAC-1

y = 4.42E+05e7.92E+00x

R2 = 9.62E-01

y = 6.65E+02e1.14E+01x

R2 = 9.58E-01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

1.E+08

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35

Carbonyl Content (1700 cm-1), au

Shea

r M

odul

us, G

*, a

t 10

rad/

s

25°C unaged 25°C RTFO25°C PAV at 60°C 25°C PAV at 80°C25°C PAV at 100°C 60°C unaged60°C RTFO 60°C PAV at 60°C60°C PAV at 80°C 60°C PAV at 100°C

G* Correlations With Carbonyl Content For AAC-1

32

AAD-1y = 4.22E+05e1.69E+01x

R2 = 9.23E-01

y = 1.64E+03e2.48E+01x

R2 = 9.74E-01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

1.E+08

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35

Carbonyl Content (1700 cm-1), au

Shea

r Mod

ulus

, G*,

at 1

0 ra

d/s

25°C unaged25°C RTFO25°C PAV at 60°C25°C PAV at 80°C25°C PAV at 100°C60°C unaged60°C RTFO60°C PAV at 60°C60°C PAV at 80°C60°C PAV at 100°C

G* Correlations With Carbonyl Content For AAD-1

33

AAM-1y = 1.60E+06e5.07E+00x

R2 = 9.46E-01

y = 3.92E+03e1.02E+01x

R2 = 9.72E-01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

1.E+08

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35Carbonyl Content (1700 cm-1), au

Shea

r Mod

ulus

, G*,

at 1

0 ra

d/s

25°C unaged25°C RTFO25°C PAV at 60°C25°C PAV at 80°C25°C PAV at 100°C60°C unaged60°C RTFO60°C PAV at 60°C60°C PAV at 80°C60°C PAV at 100°C

G* Correlations With Carbonyl Content For AAM-1

Wave Number, cm-1