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  • COMPATIBILITY OF RAP AND

    VIRGIN BINDER

    2012 Arizona Pavements/Materials Conference

    October 31, 2012

    Michael Harnsberger

  • Introduction

    • Early in the 20th Century, it became apparent that

    asphalt performance varied

    • Derived from different crude sources

    • Even asphalts of the same grade

    • Classification methods developed

    • Composition based

    • Rheology based

    • Crude oil methods adapted

  • Introduction

    • Asphalt behaved as a colloidal system (Traxler)

    • Asphaltenes dispersed in maltene solvent

    • Asphalts classified as sol or gel

    • Sol asphalts are more compatible

    • Lower asphaltene content

    • Gel asphalts are less compatible

    • Higher asphaltene content

    • Many asphalts are intermediate

  • Methods for Estimation of

    Compatibility

    • Asphaltene dispersibility index

    • Asphaltene filtering rate

    • Asphaltene compatibility index (Branthaver)

    • Relative viscosity (v. asphalt/ v. maltenes)

    • Ratios of fractions (Corbett, Rostler, Schweyer, Traxler)

    • Heithaus parameters

    • pa – peptizability of the asphaltenes

    • po – peptizability of the maltenes

    • P – state of peptization

  • Composition and Compatibility

    Heithaus Test

    Solution of asphalt in toluene titrated with heptane;

    Must match

    Solvent power of petrolenes

    Dispersibility of asphaltenes

    Altgelt and Harle

    “Thickening power” of asphaltenes related to degree of

    association

    Degree of association of asphaltenes controlled by

    solvent power of petrolenes

  • Effect of Compatibility on Blending

  • Effects of Crossblending

  • Asphalt Characterization

    • Methods developed to separate asphalt components

    (maltenes)

    • Rostler Method

    • Corbett-Swarbrick method ASTM D4124

    • Clay-gel

    • Size-exclusion chromatography (GPC) (whole asphalt)

    • Ion-exchange chromatography (whole asphalt)

  • Composition Fraction Comparison

    Rostler Corbett Function

    Paraffins Saturates Gel

    2nd Acidaffins Naphthene

    Aromatics

    Fluidity

    1st Acidaffins Solvent

    Nitrogen Bases Polar Aromatics Dispersant

    Asphaltenes Asphaltenes Thickener

  • What is Compatibility?

    Operational Definition of Compatibility

    • Mixing of two or more similar materials gives expected

    results

    Incompatibility

    • Mixing of two or more similar materials gives unexpected

    results

    • Softer than expected

    • Stiffer than expected

  • Aging

    What happens when asphalts age?

    • Saturates – little oxidation/ little change

    • Aromatics – some oxidation/ small change

    • Oxidation products move to Resins

    • Resins – considerable oxidation

    • Oxidation products move to Asphaltenes

    • Asphaltenes – increase

    • Molecular associations increase

    • Asphalt aging decreases with pavement depth

  • RAP and Virgin Binder

    • Virgin and RAP asphalts mix --- Degree?

    • Age of RAP affects blending

    • Some components more “available”

    • Adsorption effects of RAP aggregate

    • Solubility “Power” of virgin asphalt

    • Is compatibility of virgin and RAP an issue?

    • Depends

    • Compatibility depends on solubility

    • Combined binder rheology will be a function of

    compatibility

  • RAP Compatibility Work

    • Lab blends of virgin and RAP @ 0,15 & 50%

    • 2 asphalts of different composition

    • 4 RAP; MB, SC, IA, & CA

    • Rheology

    • Heithaus parameters

    • Separation methods, etc.

    • Evaluation of NCSPC plant-mix samples

  • Virgin Asphalt RAP Blends

  • Virgin Asphalt RAP Blends

    0.E+00

    1.E+07

    2.E+07

    3.E+07

    4.E+07

    5.E+07

    6.E+07

    7.E+07

    8.E+07

    0 20 40 60 80 100

    G*,

    Pa,

    0C

    , 10r

    ad/s

    ec

    Percent Manitoba RAP

    AAA/Manitoba 0°C

    1.00E+07

    2.00E+07

    3.00E+07

    4.00E+07

    5.00E+07

    6.00E+07

    7.00E+07

    8.00E+07

    0 20 40 60 80 100

    G*,

    Pa,

    0C

    , 10

    rad

    /se

    c

    Percent Manitoba RAP

    AAC/Manitoba 0°C

  • Virgin Asphalt RAP Blends

    0.E+00

    1.E+04

    2.E+04

    3.E+04

    4.E+04

    5.E+04

    6.E+04

    7.E+04

    8.E+04

    0 20 40 60 80 100

    G*,

    Pa,

    60

    C, 1

    0 ra

    d/s

    ec

    Percent S. Carolina RAP

    AAA/SC RAP 60°C

    0.E+00

    1.E+04

    2.E+04

    3.E+04

    4.E+04

    5.E+04

    6.E+04

    7.E+04

    8.E+04

    0 20 40 60 80 100G

    *, P

    a, 6

    0C

    , 10

    rad

    /se

    cPercent S. Carolina RAP

    AAC/SC RAP 60°C

  • Virgin Asphalt RAP Blends

    0.0E+00

    2.0E+07

    4.0E+07

    6.0E+07

    8.0E+07

    1.0E+08

    1.2E+08

    1.4E+08

    1.6E+08

    1.8E+08

    0 20 40 60 80 100

    G*,

    Pa,

    0C

    , 10

    rad

    /se

    c

    Percent S. Carolina RAP

    AAA/SC RAP 0°C

    0.0E+00

    2.0E+07

    4.0E+07

    6.0E+07

    8.0E+07

    1.0E+08

    1.2E+08

    1.4E+08

    1.6E+08

    1.8E+08

    0 20 40 60 80 100G

    *, P

    a, 0

    C, 1

    0 ra

    d/s

    ec

    Percent S. Carolina RAP

    AAC/SC RAP 0°C

  • NCSC Plant Mix Study

    • 5 contractors produced 6 RAP mixes

    • PG 64-22 with 0, 15, 25, and 40% RAP

    • PG 58-28 with 25 and 40% RAP

    • Mix Testing

    • Dynamic modulus and Low Temp IDT

    • Binder extracted and graded

    • Samples of binder sent to WRI for

    compatibility (4 of 5)

  • Mix Properties vs. Compatibility

    4.20

    4.30

    4.40

    4.50

    4.60

    4.70

    4.80

    4.9015

    20

    25

    30

    1A-0% 1B-15% 1C-25% 1D-40% 1E-25% 1F-40%

    AF

    T, P

    valu

    e

    Sti

    ffn

    ess, G

    Pa

    Stiffness

    AFT, P value

    64-22 58-28

    Stiffness data from: Investigation of Low and High Temperature Properties

    of Plant-Produced RAP Mixtures Phase II, McDaniel and Huber

  • 3.80

    3.90

    4.00

    4.10

    4.20

    4.30

    4.40

    4.50

    4.60

    4.70

    4.80

    4.90

    5.00

    5.1010

    15

    20

    25

    30

    2A-0% 2B-15% 2C-25% 2D-40% 2E-25% 2F-40%

    AF

    T, P

    valu

    e

    Sti

    ffn

    ess, G

    Pa

    Stiffness

    AFT, P value

    Mix Properties vs. Compatibility

    64-22 58-28

    Stiffness data from: Investigation of Low and High Temperature Properties

    of Plant-Produced RAP Mixtures Phase II, McDaniel and Huber

    -22.1 -21.9 -21.8 -21.3 -24.1 -23.3

  • 3.20

    3.30

    3.40

    3.50

    3.60

    3.70

    3.80

    3.90

    4.00

    4.10

    4.2020

    25

    30

    35

    3A-0% 3B-15% 3C-25% 3D-40% 3E-25% 3F-40%

    AF

    T, P

    valu

    e

    Sti

    ffn

    ess, G

    Pa

    Stiffness

    AFT, P value

    Mix Properties vs. Compatibility

    64-22 58-28

    Stiffness data from: Investigation of Low and High Temperature Properties

    of Plant-Produced RAP Mixtures Phase II, McDaniel and Huber

    -22.5

    -21.8

    -21.4

    -20.3

    -21.3

    -24.5

  • 4.40

    4.50

    4.60

    4.70

    4.80

    4.90

    5.00

    5.10

    5.20

    5.30

    5.4015

    20

    25

    30

    4A-0% 4B-15% 4C-25% 4D-40% 4E-25% 4F-40%

    AF

    T, P

    valu

    e

    Sti

    ffn

    ess, G

    Pa

    Stiffness

    AFT, P value

    Mix Properties vs. Compatibility

    64-22 58-28

    Stiffness data from: Investigation of Low and High Temperature Properties

    of Plant-Produced RAP Mixtures Phase II, McDaniel and Huber

    -20.5

    -20.8

    -20.5

    -19.6 -24.2 -23.3

  • Comments

    • Lab binder blending study using rheology and compatibility

    will hopefully provide more insight

    • Lab tests must correlate to plant mixing

    • Goals of this are:

    • Better understanding of RAP/Virgin blending

    • Quick material evaluation method to determine the amount of

    RAP/RAS blending with new asphalt

    • If oil prices rise, asphalt crude sources/blends are sure to

    change

  • Acknowledgements

    • This work performed under FHWA Contract DTFH61-07-H-0009

    Asphalt Research Consortium

    • WRI – Troy Pauli, James Beiswenger

    • North Central Superpave Center & Heritage Research

    • Becky McDaniel and Gerald Huber

of 24/24
COMPATIBILITY OF RAP AND VIRGIN BINDER 2012 Arizona Pavements/Materials Conference October 31, 2012 Michael Harnsberger
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