TPF 5(153) Optimal Timing of Preventive Maintenance for Addressing - - PowerPoint PPT Presentation

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TPF 5(153) Optimal Timing of Preventive Maintenance for Addressing - - PowerPoint PPT Presentation

Jul 01, 2023 268 likes •445 views

TPF 5(153) Optimal Timing of Preventive Maintenance for Addressing Environmental Aging Michael Heitzman, PhD, PE Assistant Director, NCAT at Auburn University TRAFFIC CLIMATE Weight Frequency Temperature high/low Moisture

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TPF – 5(153) Optimal Timing of Preventive Maintenance for Addressing Environmental Aging Michael Heitzman, PhD, PE Assistant Director, NCAT

at Auburn University

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SLIDE 2

ASPHALT BINDER

Stiffness/Flexibility Modification

CLIMATE

Temperature – high/low Moisture

AGGREGATE

Gradation Quality Shape Texture Absorption

MIXTURE

Air voids VMA – VFA Film thickness Stripping Strength Filler:binder ratio

SUBGRADE

Material Moisture Compaction Strength

PAVEMENT STRUCTURE

Mixture Thickness

CONSTRUCTION

Uniformity Density Smoothness

MAINTENANCE

Sealing Repair Rehabilitation

TRAFFIC

Weight Frequency

RUTTING FATIGUE STRIPPING AGING THERMAL CRACK FRICTION RAVELING

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Summary of Recent Projects

  • Analysis method to better quantify film

thickness

  • Analysis method to measure binder aging

without large extracted samples

  • Better characterization of mineral filler

at Auburn University

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Film Thickness

Development of new film thickness models for hot mix asphalt

Michael Heitzman 2005 dissertation Iowa State University, Ames, Iowa

New Approaches for Computing Film Thickness

Michael Heitzman Iowa Department of Transportation 2006 AAPT additional paper, not presented

at Auburn University

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Random Spatial Distribution

Film Thickness (VIRTUAL Model) a1t + a2t2 + a3t3 = ln(1-Vs / Va)

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Air Void Impact Grad-C MF=6% Gsb=2.55

6.00 7.00 8.00 9.00 10.00 11.00 12.00 2 4 6 8 10 12 Compacted voids Film Thickness (microns)

INDEX STANDARD VIRTUAL

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Air Asphalt Binder Mineral Filler Fine Aggregate Coarse Aggregate

Standard INDEX VIRTUAL MASTIC Research Beyond Film Thickness??

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Measuring Binder Aging

Reducing Stiffness of Oxidized Binder in Recycled Asphalt Mixture by Stage Mixing

Kwang W. Kim, Jaehun Jung, and Young S. Doh Kangwon National University, Chuncheon, Korea Serji N. Amirkhanian Clemson University, Clemson, SC AAPT 2007

at Auburn University

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Measuring Binder Aging

The Test Method

“Since the oxidation is a process that changes molecular size distribution of the binder, … it is possible to utilize gel-permeation chromatography (GPC) to detect this delicate change of molecular size distribution. Many studies have already shown that a relatively high correlation exists between viscosity and corresponding large molecular size (LMS) distribution in the GPC profile.” “In this GPC method, a small amount of mixture particle was dissolved into a solvent (tetrahydrofuran: THF) and a GPC sample was collected from the filtered dissolution.”

AAPT paper

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Measuring Binder Aging

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Mineral Filler

We know very little about the mineral filler

  • Physical properties (gradation, shape)
  • Chemical properties
  • Proportion in the mixture

Mineral Filler Gradation

0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0 0.075 0.05 0.02 0.01 0.005 0.001 Sieve size (mm) Percent passing

Data from AAPT Vol 52, 1983

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Mineral Filler

  • NCHRP 09-45 Development of Specification

Criteria for Mineral Fines Used in HMA

– 3-year study started in 2007 – PI is Dr. Hussian Bahia, University of Wisconsin - Madison

  • Effect of Ultrafine Particles on Linear

Viscoelastic Properties of Mastics and Asphalt Concretes

– TRB 2008 paper 08-0865 – Delaporte et al, France

at Auburn University

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What is needed

  • Comprehensive study of the mechanisms

that influence MIXTURE aging MIXTURE Aging = mixture performance change as the asphalt binder ages Mixture performance = rutting, fatigue, low temperature cracking

at Auburn University

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Nationally Combined Efforts

  • FHWA directed research (ex: WRI, NCAT)
  • NCHRP (2-3 year development period)
  • Pooled fund (committed DOTs)

at Auburn University

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Emphasis of this project

  • Can we optimize the preventive

maintenance, if we do not understand what we are measuring?

  • Do we understand the aging process?

Yes.

  • Do we know what factors influences aging?

Yes.

at Auburn University

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Emphasis

  • Do we know what factors are most important?
  • No. We need a better understanding of the critical

factors, then determine how to best control them.

  • Do we know how the factors that influence aging

impact other key performance criteria (rutting, fatigue, ...)? We cannot study aging without

recognizing that HMA performance is complex.

  • What is the best way to measure aging?

Binder or mixture response? We cannot ignore

mixture response. If binder ages, but mixture performance does not change … then aging is at acceptable levels.

at Auburn University

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Closing comments

  • There is no single magic bullet.
  • Research must keep one eye focused on

the practical application of the results.

  • Do not narrow the research to binder only.

Include mixture and mastic.

at Auburn University