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NCHRP Project No. NCHRP 9-44 A Validating an Endurance ... · PDF file NCHRP Project No. NCHRP...

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  • NCHRP

    Project No. NCHRP 9-44 A

    Validating an Endurance Limit for Hot-Mix Asphalt (HMA) Pavements:

    Laboratory Experiment and Algorithm Development

    Appendix 1

    Integrated Predictive Model for Healing and Fatigue Endurance Limit for Asphalt Concrete

    Prepared for

    NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM TRANSPORTATION RESEARCH BOARD

    Of The National Academies

    Submitted by:

    Matthew Witczak, Project P.I. Michael Mamlouk, Project Co-P.I.

    Mena Souliman, Research Assistant Waleed Zeiada, Research Assistant

    July 2013

  • i

    Table of Contents Page

    CHAPTER 1 .................................................................................................. 1 

    INTRODUCTION ......................................................................................... 1 

    BACKGROUND OF FATIGUE CRACKING ................................. 1 

    BACKGROUND OF THE HMA ENDURANCE LIMIT ................ 1 

    PROBLEM DEFINITION .................................................................. 3 

    RESEARCH OBJECTIVES ............................................................... 3 

    SCOPE OF RESEARCH .................................................................... 3 

    REPORT ORGANIZATION ............................................................. 4 

    CHAPTER 2 .................................................................................................. 6 

    LITERATURE REVIEW .............................................................................. 6 

    FATIGUE CRACKING MECHANISMS ......................................... 6 

    “Bottom-Up” Fatigue Cracking–Alligator Cracking .................6  “Top-Down” Fatigue Cracking–Longitudinal Cracks in Wheel Path 7 

    FATIGUE LIFE MODELS AND RELATIONSHIPS ...................... 7 

    General Fatigue Model ..............................................................7  Fatigue Life Relationships .........................................................7 

    FATIGUE CRACKING PREDICTION EQUATION APPROACHES 9 

    LABORATORY FATIGUE TESTS .................................................. 9 

    Adjustment to Lab Fatigue Curves ............................................9  Fatigue Failure Criteria ............................................................10  Selection of the Failure Criterion .............................................13 

    FACTORS AFFECTING FATIGUE CRACKING RESPONSE ... 14 

    Asphalt Content and Air Voids ................................................14  Aggregate Gradation ................................................................14  Mode of Loading ......................................................................15 

  • ii

    Rest Period ...............................................................................16  FATIGUE TEST TYPES .................................................................. 19 

    Flexure Beam Test ...................................................................20  Cantilever Beam Rotating Test ................................................20  Trapezoidal Cantilever Beam Test ...........................................20  Supported Flexure Test ............................................................21  Triaxial Test .............................................................................21  Direct Tension Test ..................................................................21  Tension/Compression Test .......................................................22  Diametral Test ..........................................................................22  Wheel-Track Test .....................................................................22 

    HEALING OF HMA ........................................................................ 23 

    Healing Mechanism .................................................................23  Effect of Healing on Fatigue Life ............................................24  Field Tests ................................................................................26 

    HMA ENDURANCE LIMIT ........................................................... 26 

    Historical Background .............................................................26  Endurance Limit Studies ..........................................................27 

    CHAPTER 3 ................................................................................................ 31 

    STATISTICAL DESIGN OF EXPERIMENT ........................................... 31 

    BACKGROUND .............................................................................. 31 

    NCHRP PROJECT 9-44 PROPOSED DESIGN ............................. 31 

    Asphalt Binder Type ......................................................................... 32

    Asphalt Binder Aging……………………………………………32 Compaction Level ............................................................................. 33 

    Gradation and Filler Content ............................................................ 33 

    NCHRP PROJECT 9-44A DESIGN ................................................ 33 

    Six-Factor Design ....................................................................34 

  • iii

    Six-Factor Full Factorial Design ........................................36  Six-Factor Fractional Factorial Design with Complete Randomization ............................................................................................36  Six-Factor Fractional Factorial Design with Partial Randomization 37 

    Five-Factor Design...................................................................38 Five-Factor Full Factorial Design………………………………………………39 Five-Factor Fractional Factorial Design with Complete Randomization……….39 Five-Factor Fractional Factorial Design with Partial Randomization ............................................................................................40 

    Comparing Six-Factor and Five-Factor Factorial Designs ......40  Other Detailed Experiments .....................................................41 

    Final Design....................................................................................... 41 

    CHAPTER 4 ................................................................................................ 42 

    MATERIALS AND MIX DESIGN ............................................................ 42 

    BACKGROUND .............................................................................. 42 

    MATERIALS .................................................................................... 42 

    BINDER AGING METHODS ......................................................... 42 

    ASPHALT BINDER TEST RESULTS ........................................... 43 

    Viscosity—Temperature Curves ..............................................43  Performance-Graded Binder Characterization Tests ...............44 

    ASPHALT BINDER CHARACTERIZATION TO DEVELOP AN Ai-VTSi

    RELATIONSHIP .............................................................................. 47 

    Data Analysis ...........................................................................47  MIX DESIGN AND AGGREGATE BLEND RESULTS .............. 49 

    CHAPTER 5 ................................................................................................ 52 

    SPECIMEN PREPARATION AND TESTING MACHINE CALIBRATION 52 

    MOLD ASSEMBLY AND SPECIMEN PREPARATION ............ 52 

  • iv

    Mold Assembly ........................................................................52  Specimen Preparation ..............................................................53  Aggregate Batching .................................................................53  Binder Preparation ...................................................................53  HMA Mixing ...........................................................................53  Short Term Aging ....................................................................54  Obtaining Maximum Theoretical Specific Gravity (Gmm) .......54  Compacting HMA Beams ........................................................54  Determining Desired Air Voids ...............................................55 

    FLEXURAL BEAM FATIGUE APPARATUS .............................. 56 

    TEST PROCEDURE AND CALCULATIONS .............................. 56 

    BEAM FATIGUE APPARATUS CALIBRATION ....................... 57 

    LVDT Calibration Procedure ...................................................57  Load Cell Calibration Procedure .............................................58  Temperature Calibration Procedure .........................................59 

    CHAPTER 6 ................................................................................................ 60 

    PRELIMINARY QUALITY CONTROL/QUALITY ASSURANCE STUDIES 60 

    EVALUATION OF EQUALITY AMONG MACHINES USING

    SYNTHETIC BEAMS WITH NO REST PERIOD ........................ 60 

    Experimental Conditions .........................................................60  Experimental Results ...............................................................60  Testing the Adequacy of the Statistical Model ........................61  Comparison of IPC1 and IPC2 Machines ................................61  Experimental Results after Recalibration and Tunin

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