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Cold Recycling & Bitumen Stabilised Materials BSMs ... Cement : Foamed Bitumen Ratio k 0 500 1000 1500 2000 2500 3000 3500 4000) Foamed bitumen, Strain Cement, Strain* Foamed bitumen,

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  • tellenbosch

    Cold Recycling & Bitumen

    Stabilised Materials BSMs

    Research and

    Implementation?

    tellenbosch

    Kim Jenkins

    57th Annual Illinois Bituminous

    Paving Conference 12th December 2016

    Outline

    1. What is BSM?

    2. Mix Design

    3. Structural Design

    4. Application

    5. Where to now?

  • BSM Binder Options

    FOAMED BITUMEN

    Mill

    Acid or

    Caustic Soda

    Surfactants

    Wat BitumenWater

    5 microns

    Water

    Hot

    bitumen

    Air

    Expansion chamber

    BITUMEN EMULSION

    Colloidal Mill

    Flexibility

    R ig

    id it

    y

    320 1

    3

    4 5

    4

    2

    1

    0

    C e m

    e n

    t %

    Bitumen % 6

    Cement stabilised

    Bound

    Granular

    Unbound

    Non-

    continuously

    Bound

    BSM

    Asphalt

    Bound

    Orientation on BSM

  • Influence of Active Filler

    Strength versus Flexibility

    0

    100

    200

    300

    400

    500

    600

    700

    800

    0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3

    Cement : Foamed Bitumen Ratio

    S tr

    a in

    -a t-

    b re

    a k

    0

    500

    1000

    1500

    2000

    2500

    3000

    3500

    4000

    U n

    c o

    n fi

    n e d

    C o

    m p

    re s s iv

    e

    S tr

    e n

    g th

    ( k P

    a )

    Foamed bitumen, Strain

    Cement, Strain*

    Foamed bitumen, UCS

    Cement, UCS*

    * Cement treated with 2 percent cement and no foamed bitumen. Values plotted at an arbitrary ratio of 1.25 for 2 percent cement and 1.2 for 1 percent cement.

    CSIR

    BSM

    eb

    BSM foam

    Cement < 1%

    BSM Triaxial Tests Shear properties (monotonic tests at 25°C)

    Cohesion C

    0

    100

    200

    300

    400

    500

    A -7

    5 C

    -0

    B -7

    5 C

    -0

    C -7

    5 C

    -0

    A -7

    5 C

    -1

    B -7

    5 C

    -1

    C -7

    5 C

    -1

    A -7

    5 M

    -0

    B -7

    5 M

    -0

    C -7

    5 M

    -0

    C o

    h e s io

    n [

    k P

    a ]

    E E E E E E FFF 20

    25

    30

    35

    40

    45

    50

    A -7

    5 C

    -0

    B -7

    5 C

    -0

    C -7

    5 C

    -0

    A -7

    5 C

    -1

    B -7

    5 C

    -1

    C -7

    5 C

    -1

    A -7

    5 M

    -0

    B -7

    5 M

    -0

    C -7

    5 M

    -0

    F ri

    c ti

    o n

    a n

    g le

    [ d

    e g

    re e s ]

    Friction Angle f

    E E E E E E FFF

    Jenkins, 1999 & Ebels, 2006

    25% RAP 25% RAP75% RAP 75% RAP

  • Resilient Modulus of BSM

    Stress dependency: Foamed BC = 2%

    150

    350

    550

    750

    950

    1150

    1350

    0.0 200.0 400.0 600.0 800.0 1000.0

    Sum of Principal Stresses q (kPa)

    R e

    s il ie

    n t

    M o

    d u

    lu s M

    r (M

    P a

    )

    12kPa

    24kPa

    48kPa

    72kPa

    s3

    HMA > 2500 MPa

    GCS

    BSM

    Research: Visco-elasto-plastic & flexural properties on BSM-foam

    Tref = 20C

    HMA/WMA

    HW Fatigue cracks

    Rutting

    HOT T or

    Slow Traffic Equiv

    COLD T or

    Fast Traffic Equiv

    BSM

    BSM

  • BSM test methods

    Years

    20101990 2000

    Reality Index

    Compaction

    Testing Z

    e

    r

    o

    L

    i

    n

    e

    S

    l

    e

    e

    v

    e

    B

    a

    s

    e

    P

    l

    a

    t

    e

    S

    t

    e

    e

    l

    R

    o

    d

    S

    id

    e

    o

    f

    M

    o

    ul

    d

    V

    i

    b

    r

    a

    t

    o

    r

    y

    H

    a

    m

    m

    e

    r

    W

    o

    o

    d

    e

    n

    b

    a

    s

    e

    C,f Mix design to Performance Design BSM layers

    h1 h2 h3

    >200 project mix designs!

    Mix Design Flowchart

    Sampling

    Sample preparation

    Preliminary tests

    SUITABLE?

    Blend

    Effect of active filler

    Optimum bitumen addition

    Determine shear

    properties

    Yes

    No

    ITS

    TRIAXIAL

    Specification

    C (kPa) f (0)

    >250 >40

  • PUGMILL MIXER

    FOAMED BITUMEN UNIT

    Standardised Mixing Method

    Lab Compaction: Vibratory Hammer

    Vibratory hammer

    Power rating (W)

    Frequency (Hz)

    Mass (Kg)

    Point Energy (J)

    Kango 637® 750 45.83 7.5 27

    Bosch GSH 11E® 1500 15 - 31.5 10.1 16.8

    Bosch GSH 11VC® 1700 15 - 30 11.4 23

    For PI >8%, cannot achieve 100% Mod. AASHTO density

  • Influence of Frame

    2050

    2100

    2150

    2200

    2250

    2300

    2350

    2400

    G2 G4

    D e n

    s it

    y (

    k g

    /m 3 )

    Material Type

    80% OMC, RFR, 10kg Surcharge

    80% OMC, LFR, 10kg Surcharge

    80% OMC, RFR, 20kg Surcharge

    80% OMC,LFR, 20kg Surcharge

    Refusal Density

    Comparison of refusal density for G2 and G4 material

    FRAME TYPE

    Rigid

    Loose

    Rigid

    Loose

    (Stell Univ)

  • Inter-Layer Roughening (ILR) Device

    6 layers X 50mm

    2 layersITS

    Triaxial

    Inventor: Wynand van Niekerk

    CT Scans BSM-emulsion

    S1A

    -5

    5

    15

    25

    35

    45

    55

    65

    75

    85

    0 20 40 60 80 100

    Volume in %

    S c a

    n s

    li c e

    n u

    m m

    e r

    (b o

    o rk

    e rn

    l e

    n g

    te i

    n m

    m ).

    voids

    Mortar

    stone

    Poor attention to

    interlayer preps

  • tellenbosch

    N7 PSPA Mr Analysis over 7 Months

    0

    500

    1000

    1500

    2000

    2500

    3000

    3500

    4000

    0 50 100 150 200 250

    Time (days)

    M r

    (M P

    a )

    B1-B3 B4-B6 Poly. (B4-B6)

    PSPA

    Moisture

    Mr

    Why is curing important?

    Mr (field) versus cure

    % OMC

    100

    40

    60

    80

    MC

    New Triaxial

    Confining Pressure s3 (inflate tube)

    Apply Load (stress s1)

    Test at

    25ºC

  • tellenbosch

    Validation Research Triaxial Test RTT versus

    Simple Triaxial Test STT

    0

    200

    400

    600

    800

    1000

    1200

    1400

    0.0 1.0 2.0 3.0 4.0 5.0

    Strain [%] A

    p p

    li e d

    S tr

    e s s [

    k P

    a ]

    RTT

    STT

    0

    200

    400

    600

    800

    1000

    1200

    0.0 1.0 2.0 3.0 4.0

    Strain [%]

    A p

    p li

    e d

    S tr

    e s s [

    k P

    a ]

    RTT

    STT

    BSM Crushed Hornfels with 3.3% Emulsion

    s3 =50 kPa and 1% Cement s3 = 200 kPa and 0% Cem

    APPLY CONFINING PRESSURE (AIR)

    APPLY LOAD (3mm/min)

    σ1

    σ3

  • t

    s

    Shear stress

    Normal stress

    (kPa)

    Cohesion

    f Friction angle

    UNBOUND

    BSM

    σ1

    σ3

    σ1

    σ3

    0 50 100 200

    Determine shear properties (C and φ)

    Durability of BSM t

    s

    Shear

    stress

    Normal

    stress

    CBSM

    Cohesion

    f Friction

    angle

    Retained Cohesion CR = CR*100/CBSM

    Effect of

    Moisture

    Cohesion Loss = 25% max

  • Structural Design Considerations

    250mm CIPR:

    2.5% Foam 1% Cem

    90mm Asphalt

    Lab Triaxial Analysis

    Permanent deformation (rutting) design for granular material

    BSM Design for Max Rut Depth (same principle as Granular Design)

    Design Life for 10mm rut

  • Design Function for BSM

    𝑁 = 𝑓 (𝑅𝐷, 𝑅𝑒𝑡𝐶, 𝑃𝑆, 𝑆𝑅)

    Relative Density Plastic Strain (a/b)

    Retained Cohesion Stress Ratio

    a b

    Mr change with trafficking (triaxial)

    0.0

    200.0

    400.0

    600.0

    800.0

    1000.0

    1200.0

    1400.0

    1600.0

    1800.0

    2000.0

    100 1,000 10,000 100,000 1,000,000

    R e s il

    ie n

    t M

    o d

    u li

    ( M

    P a )

    .

    Load repetitions

    SR