CEDR Transnational Road Research ProgrammeCall 2012: Recycling: Road construction in a post-fossil fuel societyfunded by Denmark, Finland, Germany,Ireland, Netherlands and Norway
Toward a sustainable 100% recycling of reclaimed asphalt in road pavements
Gustavo Canon FallaResearch Fellow, Institute of urban and pavement engineering
Technische Universität Dresden
International workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
http://allback2pave.fehrl.orgInternational workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
Objectives
AllBack2Pave is a research project project that will evaluate the feasibilityof going towards 100% recycling of asphalt pavements into surfacecourses.
http://allback2pave.fehrl.orgInternational workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
Objectives
AllBack2Pave is a research project project that will evaluate the feasibilityof maximizing the amount of recycling of asphalt pavements intosurface courses.
The main objectives of the project are:
• To establish, through laboratory tests on binders and asphalt mixes,whether the use of high rates of RA is feasible in developing mixeswith a high level of performance which do not affect the durability.
• To develop the so-called “AllBack2Pave end-user manual” on how tobest produce cost-effective and quality asphalt mixes with high RAcontent.
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Consortium
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Project organization
http://allback2pave.fehrl.orgInternational workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
Project organization
http://allback2pave.fehrl.orgInternational workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
Methodology
• Two typical asphalt surface mixes ofhigh volume roads of Germany andItaly.
• Mix design and production followingeach country regulatory environment.
• Three different amounts of RA in eachmix.
Control mixes
DE: SMA 8S
IT: AC 16
Control mixes
DE: SMA 8S
IT: AC 16
30% RA
DE30
IT30
30% RA
DE30
IT30
60% RA
DE60
IT60
60% RA
DE60
IT60
Max% RA
DE60+Add.
IT90
Max% RA
DE60+Add.
IT90
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Materials: DE
Cold virgin aggregatesHot virgin aggregatesFibresFinesCold RAHot RAVirgin BitumenAdditivesHot mix
1 Stockpiles of virgin aggregates2 Cold Feeders3 Aggregates heating drum4 Fibre silo5 Aggregate elevator6 Filler silo7 Screen / Fractioning8 Aggregate scale9 Parallel heating drum for RA10 Bitumen tank11 RA elevator12 RA screen13 Stockpiles of RA14 Mixer15 Additive addition16 Hot mix storage silo
http://allback2pave.fehrl.orgInternational workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
Materials: DE
Sand
Fine
sFi
bres
Virg
inB
itum
enA
dditi
ves
RA
Coa
rse
Agg
rega
tes Crushed stone 8/11 Quarry in Gilching
2 buckets of 15kg each foreach aggregate.
Crushed stone 8/11 Quarry in TreidlingCrushed stone 5.6/8
Crushed stone 2/5.6 Quarry in Treidling
Material Source / Producer Sampling
Quarry in GilchingCrushed stone 5.6/8 Quarry in TreidlingCrushed stone 2/5.6 Quarry in Gilching
Sand 0/2 Quarry in Gilching 2 buckets of 15kg each
Fines Quarry in Lauterhofen 1 bucket of 15 kg
Fibres Viatop premium 1 bucket of 5 kg
Bitumen(PmB 25/55-55) OMV 1 bucket of 15 Kg
Blend of rejuvenatorand WMA Storimpex 1 sample of 5 kg was
obtained from the producer
Reclaimed asphaltSMA 11S
Rehabilitation of A8 highwaynear Munich
10 buckets of 15 kg each.The buckets were filled withRA from 5 random locations ofthe stockpile
Virginminerals
Virginminerals FibresFibres Virgin
bitumenVirgin
bitumen AdditiveAdditive RARA
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Materials: IT
Virginminerals
Virginminerals
VirginbitumenVirgin
bitumen AdditiveAdditive RARA
http://allback2pave.fehrl.orgInternational workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
Hot mix recycling process
Reclaim theasphalt
Process theRA
Characterizethe RA
Mix designMixingTransport andpaving
Maintenance End of lifeReclaim the
asphalt (multiplerecycling)
http://allback2pave.fehrl.orgInternational workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
Reclaim the asphalt
• Mill out from the surface layer of ahigh volume road near Munich(highway A8).
• The RA was made up of abituminous surface originallydesigned as a SMA with a nominalgrain size of 11mm (SMA 11S) anda Polymer modified bitumen (PmB25/55-55).
• The original mix design formulasand maintenance history of the RAwere not available
German RA Italian RA
• Mill out from the surface layer ofan urban road
• The RA was made up of abituminous surface originallydesigned as an AC with a nominalgrain size of 16mm
• The original mix design formulasand maintenance history of the RAwere not available
http://allback2pave.fehrl.orgInternational workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
• Mill out from the surface layer ofan urban road
• The RA was made up of abituminous surface originallydesigned as an AC with a nominalgrain size of 16mm
• The original mix design formulasand maintenance history of the RAwere not available
Reclaim the asphalt
• Mill out from the surface layer of ahigh volume road near Munich(highway A8).
• The RA was made up of abituminous surface originallydesigned as a SMA with a nominalgrain size of 11mm (SMA 11S) anda Polymer modified bitumen (PmB25/55-55).
• The original mix design formulasand maintenance history of the RAwere not available
German RA Italian RA
RA properly milled (i.e. layer by layer)
Mix desing formulas, material andmaintenance records of RA
RA properly milled (i.e. layer by layer)
Mix desing formulas, material andmaintenance records of RA
http://allback2pave.fehrl.orgInternational workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
Hot mix recycling process
Reclaim theasphalt
Process theRA
Characterizethe RA
Mix designMixingTransport andpaving
Maintenance RehabilitationReclaim the
asphalt (multiplerecycling)
http://allback2pave.fehrl.orgInternational workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
Process the RA
• RA crushed in the mixing plant to amaximum grain size of 22 mm
• RA stored in stockpiles withoutfurther screening
• Open air storage
German RA Italian RA
• RA crushed in the mixing plant to amaximum grain size of 20 mm
• RA stored in stockpiles withoutfurther screening
• Under shelter storage
http://allback2pave.fehrl.orgInternational workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
Process the RA
• RA crushed in the mixing plant to amaximum grain size of 22mm
• RA storage in stockpiles withoutfurther screening
• Open air storage
German RA Italian RA
• RA crushed in the mixing plant to amaximum grain size of 20mm
• RA storage in stockpiles withoutfurther screening
• Under shelter storage
RA properly stored (e.g. under shelter)
Fractionation of RA
RA properly stored (e.g. under shelter)
Fractionation of RA
http://allback2pave.fehrl.orgInternational workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
Hot mix recycling process
Reclaim theasphalt
Process theRA
Characterizethe RA
Mix designMixingTransport andpaving
Maintenance RehabilitationReclaim the
asphalt (multiplerecycling)
http://allback2pave.fehrl.orgInternational workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
Characterize the RA
Binder extractionand recovery
Testing of RAaggregates
Testing ofBinder
Bitumen content
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Characterize the RA
Binder extractionand recovery
Testing of RAaggregates
Testing ofBinder
Mineral
Agedbitumen
BlackAggregate
WhiteAggregate
Partial blendingconcept
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Characterize the RA
Binder extractionand recovery
Testing of RAaggregates
Testing ofBinder
Blackcurve
Whitecurve
Partial blendingconcept
Greycurve
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Characterize the RA
Binder extractionand recovery
Testing of RAaggregates
Testing ofBinder
Grading
Whitecurve
German RA Italian RA
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Characterize the RA
Binder extractionand recovery
Testing of RAaggregates
Testing ofBinder
PSV.
The aggregates ability to resistskidding is crucial when designing
wearing course mixes.
http://allback2pave.fehrl.orgInternational workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
Characterize the RA
Binder extractionand recovery
Testing of RAaggregates
Testing ofBinder
Angularity
C100/0 C100/0
http://allback2pave.fehrl.orgInternational workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
Characterize the RA
Binder extractionand recovery
Testing of RAaggregates
Testing ofBinder
Conventionalproperties
http://allback2pave.fehrl.orgInternational workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
Characterize the RA
Binder extractionand recovery
Testing of RAaggregates
Testing ofBinder
Conventionalproperties
http://allback2pave.fehrl.orgInternational workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
Characterize the RA
Binder extractionand recovery
Testing of RAaggregates
Testing ofBinder
PG grade testing
http://allback2pave.fehrl.orgInternational workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
Hot mix recycling process
Reclaim theasphalt
Process theRA
Characterizethe RA
Mix designMixingTransport andpaving
Maintenance RehabilitationReclaim the
asphalt (multiplerecycling)
http://allback2pave.fehrl.orgInternational workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
Mix design
What is the maximum amount of RA that couldbe allowed in the mix?
VirginBinder
RABinder
VirginAggregates
RAAggregates
Choose highest RA that satisfies bothaggregate gradation and bitumen
requirements
Combine bitumen to meetspecification requirements
Combine aggregates tomeet gradationA
ggre
gate
path
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Mix design
The RA grading needs to be modified by additionof virgin aggregates
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Mix design
Max RA in mix: 70% -w
German Mix
Max RA in mix: 100% -w
Italian Mix
http://allback2pave.fehrl.orgInternational workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
Mix design
What is the maximum amount of RA that couldbe allowed in the mix?
VirginBinder
RABinder
VirginAggregates
RAAggregates
Choose highest RA that satisfies bothaggregate gradation and bitumen
requirements
Combine bitumen to meetspecification requirements
Combine aggregates tomeet gradation
Bitu
men
path
Blendingcharts
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Mix design
Virginbinder
property
RAbinder
property
Replaced bitumen content
The charts correlate the replaced bitumen content (RBC) with theempirical properties of the blend.
By replaced bitumen content it should be understood the percentageof bitumen from the RA in the final blend.
Blending charts
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Mix designGERMAN CASE:
• Use available RA (short term aged) and perform the design withand without rejuvenator
• Rejuvenator:o virgin PmB 25/55-55o partly rejuvenator + warm mix additive (mix)
http://allback2pave.fehrl.orgInternational workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
Mix designGERMAN CASE:
• Use available RA (short term aged) and perform the design withand without rejuvenator
• Rejuvenator:o virgin PmB 25/55-55o partly rejuvenator + warm mix additive (mix)
These charts are developed assuming that 100% of the RAbinder will be mobilized and become active part of the binder in
the new mix.
However, in reality it is also possible that part of the RA bitumenremain non-active resulting in a partial blending scenario.
http://allback2pave.fehrl.orgInternational workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
Mix design
GERMAN CASE:
Blending charts includingdegree of blending between
60% and 100%
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Mix design
GERMAN CASE:
• Binder blend design based on conventional properties shows that by using theselected binder PMB 25/55-55 as a virgin binder for the selected RA-mixes(30%,60%, and 70%), it is possible to obtain a final blend whom properties arestill within the limits of Pen and SP
%RA in the mixture
Penetration(25⁰C)(d mm)
Softening Point(⁰C)
Final Blend (30% RA) 37.3 61.5
39.7 61.0
Final Blend (60% RA)32.3 62.6
36.6 61.6
Final Blend (70% RA)30.8 63.0
35.7 61.8
target 25-55 ≥55
http://allback2pave.fehrl.orgInternational workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
Mix design
GERMAN CASE:
• Binder blend design based on performance-related properties shows that byusing the selected binder PMB 25/55 (VB-D) as a virgin binder for theselected RA-mixes (30%,60%, and 70%), it is possible to obtain a final blendwhom properties do not differ too much from the selected Virgin binder
%RA in the mixture High Tc(⁰C)
Intermediate Tc (⁰C)
Low Tc(⁰C)
Final Blend (30% RA)79.5 19.9 -15.5
79.5 19.6 -15.7
Final Blend (60% RA)79.7 20.6 -14.9
79.6 20.2 -15.4
Final Blend (70% RA)79.8 20.8 -14.8
79.6 20.1 -15.3
Target (VB-D) >79.3 <19.2 <-16.0
http://allback2pave.fehrl.orgInternational workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
Mix designITALIAN CASE:
• Use available RA (long term aged) and perform the design withrejuvenator
• Rejuvenators:o virgin bitumen 50/70o rejuvenator + warm mix additive (mix)
y = 0.0013x + 1.8325
y = 0.0025x + 1.8325
1.8
1.85
1.9
1.95
2
2.05
2.1
0 10 20 30 40 50 60 70 80 90 100
LOG
Pen
etra
tion
(25⁰C) (lo
g d
mm
)
%RVB
Rejuvenated RAPb with RejA Rejuvenated RAPb with RejB
y = 0.208x + 47.6
y = 0.181x + 47.6
0
10
20
30
40
50
60
70
80
0 10 20 30 40 50 60 70 80 90 100
Soft
enin
g P
oint
(⁰C)
%RVB
Rejuvenated RAPb with RejA Rejuvenated RAPb with RejB
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Mix design
ITALIAN CASE:• Binder’s blend design based on conventional properties shows that by
using the selected binder Pen 50/70 as a virgin binder and RejA and RejBfor the selected RA-mixes (30%,60%, and 90%), both Pen and SP valuesstruggle to achieve the target
%RA in themixture
Final properties of blendwith RejA
Final properties of blendwith RejB
Penetration(25⁰C)(d mm)
SofteningPoint(⁰C)
Penetration(25⁰C)(d mm)
SofteningPoint(⁰C)
30%RA71.0 50.5 73.7 50.273.9 53.3 79.5 52.6
60%RA70.4 53.4 79.8 52.780.3 59.0 92.9 57.5
90%RA77.3 56.4 86.5 55.287.2 64.7 108.7 62.5
target 50-70 >54 50-70 >54
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Mix design
ITALIAN CASE:• Blend design based on performance-related properties shows that by using
the selected binder Pen 50/70 as a virgin binder and RejA and RejB for theselected RA-mixes (30%, 60%, and 90%), it is possible to obtain a finalblend with comparable properties to the target binder VB.
Final properties of blendwith RejA
Final properties of blendwith RejB
Binder High Tc(⁰C)
IntTc
(⁰C)
Low Tc(⁰C)
High Tc(⁰C)
IntTc
(⁰C)
Low Tc(⁰C)
RAb 87 33 -6 87 33 -6Final Blend (30% RA –
white100) 67.1 16.9 -16.6 67.1 16.6 -14.4
Final Blend (60% RA –white100) 68.5 14.8 -18.1 68.4 14.2 -13.9
Final Blend (90% RA –white100) 69.8 12.7 -19.7 69.7 11.8 -13.3
target (VB) >66 <19 <-16 >66 <19 <-16
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Mix design process in lab
Combine virginaggregates for
gradation
Combine virginaggregates for
gradation
Heat virginaggregatesHeat virginaggregates Add RAAdd RA
Heat RA + VirginAggregates
Heat RA + VirginAggregates Add virgin bitumenAdd virgin bitumen
Performconventional
volumetric mixdesign
Performconventional
volumetric mixdesign
Performperformance tests
Performperformance tests
T=180°CTime=8h 30%,60%,90%
T=120°CTime=3h
http://allback2pave.fehrl.orgInternational workshop on Recycling: Roadconstruction in a post‐ fossil fuel society
Conclusions• The heterogeneity of the RA aggregates plays an important role when
designing asphalt mixes for wearing courses where high qualityaggregates with high resistance to wear/abrasion (polishing) areneeded.
• Properly milled (i.e. layer by layer) and stockpiled RA is a mandatoryprerequisite in order to produce durable asphalt wearing courses withhigh content of RA.
• The RA must be treated as a valuable material
• In order to produce mixes with high RA content, a balanced mix designapproach must be followed.
• One possible solution is to allow the use of high percentage of RA inwearing courses only if the RA material proceeds from the samelocation and layer where the new mix will be placed.