removing barriers to use of crumb rubber · 2019-09-05 · removing barriers to use of crumb rubber...
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Removing Barriers to Use of Crumb RubberNZTA 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
AcknowledgementsREAAA Roadshow 2016
.Background
.Highlights from the Latest NZTA Report
.Recent Development and Opportunities
.
Presentation OutlineREAAA 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 ZealandSulabiya, Kuwait
REAAA Roadshow 2016
Typical Uses for Tyre-Derived Rubber in NZ
Aim
o Transport• To enhance performance
of roading infrastructureo Environment
• To divert a high priority waste stream away from landfills
Rubber Pavements Association
REAAA Roadshow 2016
o Better chip adhesion / aggregate retentiono Increased elasticityo Crack resistanceo Rutting resistanceo Reduced fatigue failureo Less temperature sensitiveo Less maintenance / repairso Longer lives
Potential Benefits of Modified BindersREAAA Roadshow 2016
o Alternative to virgin polymer pelletso Locally sourcedo More stable pricing (NZ$750- NZ$1000 per tonne)o Security of supplyo Bitumen extendero Potentially less bitumen and virgin polymer need to be imported into NZ
Added Benefits of Crumb RubberREAAA 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, CaltransRubber Pavements Association
Wet process
REAAA Roadshow 2016
Dry Processo Higher binder content requiredo Absorbed into the rubber crumbo Patented process and unique
gradationo Introduction of crumb rubber
into asphalt plantso Higher mixing temperature
Dry Process vs. Wet Process
Wet Processo Intimate interactiono Ultrafine (At least 30-mesh)
crumb rubber preferredo Highly modified bindero Typically high viscosityo Typically specialist equipmento Typically thicker filmo Used in both chip seal and hot
mix asphalto 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 NZREAAA 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 unmodifiedo Concerns around binder compatibility and storage stability
• Further work needs to be done to address variation in binder supply
Current WorkREAAA Roadshow 2016
Basebinder
Base +5% lowviscosityWDRA
Base +10%low
viscosityWDRA
Base +16%low
viscosityWDRA
Base +15%high
viscosityWDRA
Base +22%high
viscosityWDRA
FultonHogan
rubberisedbinder
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 VJnr 3
.2 a
fter R
TFO
(kPa
-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
Basebinder
Base +5% lowviscosityWDRA
Base +10%low
viscosityWDRA
Base +16%low
viscosityWDRA
Base +15%high
viscosityWDRA
Base +22%high
viscosityWDRA
FultonHogan
rubberisedbinder
80-100+
4%SBS
80-100+
4%SBS
0
2
4
6
8
10
12
14
16
18
20
22
24Pe
ak T
ensi
le S
train
(%)
Base +
x%A
Base +
w%A
Base +
z%A
Base +
d%B
Base +
m%B
Base +
h%C
80-100 +
4%SBS1
Base 80-100 +
4%SBS2
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
o In relation to roading• Same paving technology• Less stringent performance
requiremento Enhanced performance
• Elastic• Crack resistant• Reduced maintenance
requirements
Other Road Surface Applications – Cycle tracksREAAA Roadshow 2016
Dr Jeremy WuMaterials ScientistOpus ResearchOpus International Consultants
+64 21 [email protected]
For More InformationREAAA Roadshow 2016
Research Report 578 Removing barriers to the use of crumb rubber in roadsNZ Transport Agency websitewww.nzta.govt.nz/resources/research/reports/578