Evaluating Moisture Susceptibility of Asphalt Mixes MOISTURE SUSCEPTIBILITY OF ASPHALT MIXES ... Figure 3.3 Troxler Gyratory Compactor ... step in the Superpave mix design procedure

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Text of Evaluating Moisture Susceptibility of Asphalt Mixes MOISTURE SUSCEPTIBILITY OF ASPHALT MIXES ......

  • EVALUATING MOISTURE SUSCEPTIBILITY OF ASPHALT MIXES

    Elizabeth Rae Hunter and Khaled Ksaibati Department Civil and Architectural Engineering

    University of Wyoming P.O. Box 3295

    Laramie, WY 82071-3295

    November 2002

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    Acknowledgement This report has been prepared with funds provided by the United States Department of

    Transportation to the Mountain-Plains Consortium (MPC). The MPC member universities

    include North Dakota State University, Colorado State University, University of Wyoming, and

    Utah State University.

    Disclaimer

    The contents of the paper reflect the views of the authors, who are responsible for the

    facts and the accuracy of the information presented. This document is disseminated under the

    sponsorship of the Department of Transportation, University Transportation Centers Program, in

    the interest of information exchange. The United States Government assumes no liability for the

    contents or use thereof.

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    Abstract

    This research project utilized laboratory evaluations to study effects of freeze-thaw

    cycling on the tensile strength of eight Hot Mix Asphalt mixtures and to determine if the Georgia

    Loaded Wheel Tester could be utilized to measure moisture susceptibility of Hot Mix Asphalt

    mixtures. The evaluation involved eight Hot Mix Asphalt Mixtures from combinations of two

    aggregate types and four asphalt-additive-aging possibilities. Laboratory testing was

    accomplished in the first phase with the production of 2.5 by 4 inch cores that were freeze-thaw

    cycled and tested for their indirect tensile strength following Wyoming modified AASHTO

    T283. The second phase was accomplished using 3 by 6 inch cores that were conditioned and

    tested for rutting using the Georgia Loaded Wheel Tester. Finally, a statistical analysis was

    performed to determine if performance of the various mixtures was significantly different in

    groups of asphalt types and to determine if the Georgia Loaded Wheel Tester was a viable

    measurement tool for moisture susceptibility.

    Elizabeth R. Hunter and Dr. Khaled Ksaibati University of Wyoming

    Laramie, Wyoming

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    TABLE OF CONTENTS

    CHAPTER 1 INTRODUCTION ..........................................................................................1

    Background ..................................................................................................................1

    Problem Statement .......................................................................................................1

    Objective of Research ..................................................................................................2

    Thesis Organization.....................................................................................................2

    CHAPTER 2 LITERATURE REVIEW..............................................................................3

    Introduction..................................................................................................................3

    Moisture Susceptibility ................................................................................................4

    Stripping .......................................................................................................................4

    Techniques for Limiting Moisture Susceptibility .....................................................5

    Anti-Stripping Agents .......................................................................................6

    Liquid Anti-Stripping Agents................................................................6

    Lime Additives.......................................................................................6

    Aggregate Pre-Treatment..................................................................................7

    Testing Methods for Moisture Susceptibility ............................................................8

    Boiling Water Test ............................................................................................8

    Texas Boiling Water Test..................................................................................9

    Static Immersion Test .......................................................................................9

    Lottman Test....................................................................................................10

    Tunnicliff and Root Conditioning..................................................................10

    Modified Lottman Test....................................................................................11

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    Immersion-Compression Test .........................................................................11

    Hamburg Wheel Tracking Device..................................................................12

    Texas-Freeze Thaw Pedestal Test ..................................................................15

    Georgia Loaded Wheel Tester..................................................................................15

    Chapter Summary .....................................................................................................17

    CHAPTER 3 DESIGN OF EXPERIMENT AND TESTING PROCEDURES ..............19

    Introduction................................................................................................................19

    Evaluation of the Effects of Various Freeze -Thaw Cycles on HMA Strength.......................................................................................................19

    Aggregate.........................................................................................................20

    Asphalt Cement ...............................................................................................22

    Specific Gravity Test Procedure (ASTM D70-82) .........................................25

    Theoretical Maximum Specific Gravity (AASHTO T209-94).......................25

    Production of Cores ........................................................................................26

    Percent Air Voids ............................................................................................28

    Saturation and Freeze-Thaw Cycling ............................................................29

    Resilient Modulus Test....................................................................................30

    Indirect Tensile Test........................................................................................30

    Utilizing the Georgia Loaded Wheel Tester to Test for Moisture Susceptibility ..............................................................................................................32

    Selection of Aggregate....................................................................................32

    Selection of Asphalt ........................................................................................32

    Mixing and Compaction of Specimens ..........................................................33

    Freeze-Thaw Cycling......................................................................................33

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    Saturation Procedure......................................................................................34

    Georgia Loaded Wheel Tester ........................................................................35

    Chapter Summary .....................................................................................................38

    CHAPTER 4 DATA COLLECTION..................................................................................39

    Introduction................................................................................................................39

    Materials .....................................................................................................................39

    Asphalt.............................................................................................................41

    Mixtures...........................................................................................................42

    Production of Cores ...................................................................................................43

    Phase I Cores...................................................................................................43

    Phase II Cores .................................................................................................44

    Indirect Tensile Test..................................................................................................44

    Georgia Loaded Wheel Tester..................................................................................46

    Chapter Summary .....................................................................................................49

    CHAPTER 5 ANALYSIS OF DATA..................................................................................51

    Introduction................................................................................................................51

    Statistical Analysis of Tensile Strength Ratio Data ................................................51

    Statistical Analysis of Georgia Loaded Wheel Tester Data ...................................54

    Interaction Plots for Georgia Loaded Wheel Tester Data .....................................55

    Chapter Summary ...........................................................

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