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  • Removing Barriers to Use of Crumb Rubber NZTA Research Report 578

    Jeremy Wu, Phil Herrington, Kym Neaylon

    Opus Research

    REAAA Roadshow 2016

  • o NZ Transport Agency • Research Report 578, 2015 (An output of NZTA Research Project

    ART14-26)

    o REAAA • Roadshow 2016

    o Fulton Hogan • Technical support – manufacturing and trials

    o Rubber Solutions Asia Pacific Limited • Material supplier

    o Pacific Renewables Limited • Material supplier

    Acknowledgements REAAA Roadshow 2016

  • . Background

    . Highlights from the Latest NZTA Report

    . Recent Development and Opportunities

    .

    Presentation Outline REAAA Roadshow 2016

  • What is Crumb Rubber?

    • A product of end-of-life tyres

    • 60,000+ tonnes of end-of-life tyres annually in NZ (2014)

    • Many uses including tyre-derived fuels and bitumen binder modifier

    South Auckland, New Zealand Sulabiya, Kuwait

    REAAA Roadshow 2016

  • Typical Uses for Tyre-Derived Rubber in NZ

  • Aim

    o Transport • To enhance performance

    of roading infrastructure o Environment

    • To divert a high priority waste stream away from landfills

    Rubber Pavements Association

    REAAA Roadshow 2016

  • o Better chip adhesion / aggregate retention o Increased elasticity o Crack resistance o Rutting resistance o Reduced fatigue failure o Less temperature sensitive o Less maintenance / repairs o Longer lives

    Potential Benefits of Modified Binders REAAA Roadshow 2016

  • o Alternative to virgin polymer pellets o Locally sourced o More stable pricing (NZ$750- NZ$1000 per tonne) o Security of supply o Bitumen extender o Potentially less bitumen and virgin polymer need to be imported into NZ

    Added Benefits of Crumb Rubber REAAA Roadshow 2016

  • Report outline

    o Literature review and stakeholder consultation project funded by NZTA

    • International state-of-the-art

    • National state-of-the-art

    • Historical barriers and current barriers

    • Technology advancement

    • Environmental impacts

    • Recycling

    REAAA Roadshow 2016

  • o History • 1990s enforcement for all states in the US • Currently, actively used in California, Arizona, Texas in the US • Australia has a track record in crumb rubber sprayed seals • NZ – one trial was published in the 90s (dry process)

    Background

    References: Central Laboratories Report No. 6-82/2 (1983) Transit New Zealand Research Report No.62 (1996) Land Transport New Zealand Research Report 309 (2006) Transit New Zealand Technical Memo 6001 (2006) NZ Transport Agency Research Report 578 (2015)

    Google Search – “NZTA research report 578”

    REAAA Roadshow 2016

  • • Well-established technology with ongoing improvements and innovations • Alternative to polymer modification of bituminous binders

    • PG - Performance graded asphalt binders • Austroads AGPT/T190 – Specification framework for PMBs (incl. crumb

    rubber)

    Dry process

    Crumb Rubber in Roads

    Asphalt Rubber Usage Guide, Caltrans Rubber Pavements Association

    Wet process

    REAAA Roadshow 2016

  • Dry Process o Higher binder content required o Absorbed into the rubber crumb o Patented process and unique

    gradation o Introduction of crumb rubber

    into asphalt plants o Higher mixing temperature

    Dry Process vs. Wet Process

    Wet Process o Intimate interaction o Ultrafine (At least 30-mesh)

    crumb rubber preferred o Highly modified binder o Typically high viscosity o Typically specialist equipment o Typically thicker film o Used in both chip seal and hot

    mix asphalt o Vast experience across the world

    REAAA Roadshow 2016

  • o High initial cost • Capital equipment

    o Market demand • Small PMB market ~ 5% of total bitumen market, predominantly in

    asphalt when compared to chip seals

    o Security of supply • End-of-life tyres (ELTs) are still finding their way into landfills

    o High temperature – health and safety • Difficult to be emulsified

    Key Findings – Current Barriers in NZ REAAA Roadshow 2016

  • Various Forms of Crumb Rubber

    o Crumb rubber • Mechanically ground (ambient/cryogenic) • Rubber powder / granule (70%), steel and

    textile (30%) • Mesh size – cost increases exponentially with

    decreasing size (higher mesh#)

    o Devulcanisation • Thermal/Chemical/Mechanical process • Removes cross-linking network of rubber

    (lower molecular weight) • Easier interaction with hot bitumen • Potential substitute for virgin polymer resin

    REAAA Roadshow 2016

  • o Conventional devulcanisation • High pressure, high temperature

    o New-generation • Atmospheric pressure, lower energy requirement • More environmentally friendly and cost-effective

    Devulcanisation

    Vulcanised rubber Devulcanised rubber

    REAAA Roadshow 2016

  • Report Conclusions

    o In order for a sustainable uptake of crumb rubber, we need to have: • Demand for modified binders

    • Economy of scale • Current PMB use ~5% of total bitumen market (say 150kT)

    • Sustainable and secure supply of ELTs • 60,000 tonnes of ELTs (25% are truck tyres) • To cope with potential market growth

    • Hypothetical scenario: If market grows to 25%, 7,500 tonnes of rubber may be consumed (at dosage of 20%)

    • Technology capability (from contractors’ p.o.v.) • Enabled by devulcanised rubber • Existing binder modification plants • Minimise unnecessary capital investment • Ability to be emulsified

    REAAA Roadshow 2016

  • Recommended Actions to Remove the Barriers

    o Growth of market • Assess/Quantify the performance benefits of currently used PMBs over

    unmodified binders in chip seals and asphalt • Evaluation of rubber modified binders against PMBs

    • Feasibility project on the use of devulcanised rubber for asphalt

    o Devulcanised tyre rubber • Verification of field performance of modified binders and the assessment of

    the ability to be emulsified

    REAAA Roadshow 2016

  • o Pacific Renewables Limited • Supplying devulcanised rubber • Currently in the process of establishing a plant in NZ

    o Lab assessments (Opus Research and Fulton Hogan) • Confirmed enhanced rheological properties of binders • Modified by various amounts of devulcanised rubber up to 20wt% • Dense-graded asphalt mixes were assessed in controlled lab

    environment • Improved fatigue lives using indirect tensile fatigue tests compared

    against 4%SBS PMB as well as unmodified o Concerns around binder compatibility and storage stability

    • Further work needs to be done to address variation in binder supply

    Current Work REAAA Roadshow 2016

  • Base binder

    Base + 5% low viscosity WDRA

    Base + 10% low

    viscosity WDRA

    Base + 16% low

    viscosity WDRA

    Base + 15% high

    viscosity WDRA

    Base + 22% high

    viscosity WDRA

    Fulton Hogan

    rubberised binder

    S45R 80-100 +

    4%SBS

    0.0

    0.5

    1.0

    1.5

    2.0

    2.5

    3.0

    3.5

    4.0 Grade S

    Grade H

    Grade VJ nr

    3 .2

    a fte

    r R TF

    O (k

    Pa -1 )

    Grade E

    Base +

    x%A

    Base +

    w%A

    Base +

    z%A

    Base +

    d%B

    Base +

    m%B

    Base +

    h%C

    80-100 +

    4%SBS

    S45RBase

    Effect of Crumb Rubber – Creep Recovery

    Rubberised binders

    Multiple Stress Creep Recovery (AASHTO T350) – NZTA M1-A:2016

    Grades reflects traffic volume

    REAAA Roadshow 2016

    Lower

    Higher

  • Tensile Strain at 0ºC

    Base binder

    Base + 5% low viscosity WDRA

    Base + 10% low

    viscosity WDRA

    Base + 16% low

    viscosity WDRA

    Base + 15% high

    viscosity WDRA

    Base + 22% high

    viscosity WDRA

    Fulton Hogan

    rubberised binder

    80-100 +

    4%SBS

    80-100 +

    4%SBS

    0

    2

    4

    6

    8

    10

    12

    14

    16

    18

    20

    22

    24 Pe

    ak T

    en si

    le S

    tra in

    (% )

    Base +

    x%A

    Base +

    w%A

    Base +

    z%A

    Base +

    d%B

    Base +

    m%B

    Base +

    h%C

    80-100 +

    4%SBS 1

    Base 80-100 +

    4%SBS 2

    Tensile Test – conducted at 0ºC at 150mm/min

    Rubberised binders

    REAAA Roadshow 2016

  • o Workability / lay-down trial • Logistics of binder modification and asphalt mix production • By end of October 2016

    o Odour testing • Stack emission

    o Field trial • Cycleways to be laid following the lay-down trial

    o Completion of binder performance benefit assessment

    o Reclaimed Asphalt Pavement (RAP)? • How to recycle tyre-rubber modified asphalt and chip seals?

    Where to from here? REAAA Roadshow 2016

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