Predicting Oxidative Age Hardening in Asphalt Pavement ith Ti d D th A Fi t A i tiwith Time and Depth: A First Approximation

Michael J. Farrar (mfarrar@uwyo.edu)(mfarrar@uwyo.edu)Will GrimesFred TurnerP. Michael HarnsbergerShin-Che Huang

P3 SymposiumLaramie, WyomingJ l 14 2011July 14, 2011

Rochester , MN comparative test site

Core collected 2008Core collected 2008

Project constructed 2006j

4 mm diam. parallel plate DSR

Sui C M J Farrar W H Tuminello T F Turner “New

Published reports

Sui, C., M.J. Farrar, W.H. Tuminello, T.F. Turner, New Technique for Measuring Low-Temperature Properties of Asphalt Binders with Small Amount of Materials, TRB January 2010, Washington, D.C.

S i C M J F P M H b W H25 mg Sui, C., M.J. Farrar, P. M. Harnsberger, W. H. Tuminello, T. F. Turner, “A New Low-temperature Performance Grading Method Using 4 mm Parallel-plates on a DSR”, TRB January 2011, Washington, D.C.

gsample

4‐mm dia. parallel plate DSR with machine compliance correction AASHTO T315 Determining the Rheological

Draft – modified AASHTO method

Advantages:Instrument compliance correctionLow and intermediate temp rheology

machine compliance correction g gProperties of Asphalt Binder Using a Dynamic Shear Rheometer

Working onLow and intermediate temp. rheologySmall sample (25 mg)Low heat req. (<60C)

g

Rapid alternative to AASHTO T313 (relaxation test (5 minutes) at the low PG temperature + 10°C.

MN1‐3 – 2nd sliceE* at t = 2 and t = 0 yearsy

Ext. binder

Al-Khateeb et al., AAPT, 2007)

DSR

MEPDG E* models

[Bari and Witczak , AAPT, 2006]

[Bari and Witczak AAPT 2006][Bari and Witczak, AAPT 2006]

E* ‐ GAS application

Global Aging System modelsNCHRP 1-37A Material Characterization, Design Inputs

(2.2.13)(2.2.11)

( )

(2.2.7)

MEPDG compared to extraction

Laboratory aging data for a first approximationapproximation

• 3 Aging times• 3 Aging times• RTFO• RTFO/PAV (100°C 20 hours)• RTFO/PAV (100 C, 20 hours)• RTFO/PAV (100°C, 48 hours)

4, 8, and 25 mm dia. parallel plate DSR

SAT ‐Aging scheme and rheology

Long‐term aging  convection oven atmospheric pressure

S ( 0 h 00°C) S d

DSR ‐ Low, intermediate and high temperature 

SAT(40 hours, 100°C) ~ Std. PAV rheology (4, 8 and 25 mm dia. parallel plates).Multiple stress creep recovery test (MSCR)recovery test (MSCR). Linear amplitude sweep test (LAST).

Long‐term aging( i l)

Short‐term aging  convection oven atmospheric pressure

(Pressure aging vessel)SAT(8 hours, 100°C) ~ Std. PAV

SAT(50 minutes, 150°C) ~ RTFOSAT(50 min., 130°C) ~ WMA ?

Applied Models

Christensen, D. W. and D.A. Anderson “Interpretation of mechanical test data for paving

d h l ” J l f hgrade asphalt cements.” Journal of the Association of Asphalt Paving Technologists, vol. 61, 67-116, 1992.

Brown, A. B., J. W. Sparks, and O. Larsen. Rate of Change of Softening Point, Penetration, and Ductility of Asphalt in Bituminous Pavement. Journal of Association of Asphalt Paving Technologists, Vol. 26, 1957, pp. 66-76.Paving Technologists, Vol. 26, 1957, pp. 66 76.

Global Aging System models

NCHRP 1-37A Material Characterization, Design Inputs C a acte at o , es g puts

Evolution of the CA Model parametersp

First Approximation

Comparison: Extraction, MEPDG, 1st

approximationapproximation

Conclusion

•This presentation demonstrates an approach to estimate mix dynamic modulus (E*) at any time or depth in the pavement The approach presented here involves theany time or depth in the pavement . The approach presented here involves the evolution of the Christensen-Anderson (CA) model parameters with oxidative aging .and, in addition to E*, other binder and mix mechanical properties can be estimated:

Bi d SHARP ifi i G*/ i δ G* i δ l S( )•Binder: SHARP specifications : G*/sin δ, G* sin δ, m-value, S(t)•Binder and Mix: Thermal stress build up (σT )•Binder ductility G’/η’/G’)

•The application of the Global aging system (GAS) models in the analysis may cause significant error since using an average temperature such as the mean annual air temperature (MAAT) does not take into account the heavy weighting of the reaction

t t hi h t trate at higher temperatures.

•The GAS was only used here to obtain a first approximation of E*. Work is underway to apply a two step aging scheme (a short term first order reaction and a long term zero pp y p g g ( gorder reaction) to more accurately estimate the time evolution of the CA model parameters.

Questions ?Q