Surface Mix Experience and Performance City of Edmonton

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Surface Mix Experience and PerformanceCity of
Edmonton

• Hugh Donovan, P.Eng.
• Construction Services Engineer
• Transportation Department
• City of Edmonton
• 2006 CUPGA Meeting
• Charlottown, P.E.I.

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CITY OF EDMONTON ROADWAY 2007-2011 CONSTRUCTION
BUDGET
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Estimated Aggregate Reserves

• 1978 aggregate reserves 6,980 Million tonnes
• 2,235 Million tonnes of Gravel
• 4,745 Million tonnes of Sand

• Gravel Sized Materials
• 1,036 Million tonnes of Concrete Aggregate
• 1,199 Million tonnes of Asphalt Aggregate

• Sand Sized Materials
• 2,241 Million tonnes of Dune Sand
• 200 Million tonnes potential Street Sand
• 2,304 Million tonnes Other sand materials

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1978

• Only 95 Million tonnes of Aggregate both Sand and
  Gravel had actually been confirmed in 1978

2006

• By the end of the 2006 construction season it has
  been estimated that we will have used an
  additional 432 Million tonnes of sand and gravel
  in the Edmonton region
• By 2026 given current growth we estimate that we
  will have used an additional 500 to 650 Million
  tonnes of sand and gravel in the Edmonton region

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Aggregate Supply Issues

• Current Aggregate Sources
• Are of poorer quality
• Have smaller rock fraction maximum size
• More costly to process
• Secondary processing to remove deleterious
  materials
• Further aggregate haul distances

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Aggregate Supply Issues

• Pit Logistics
• In 1978 aggregate materials came from pits
  located along the North Saskatchewan River in
  close proximity of the City (lt10km)
• In 2006 aggregate materials are coming from pits
  located well outside the City such as Wabamum,
  Villenuve, Onoway, Camrose, Smoky Lake and
  Ponoka. These pit can be as far away as
  60-135km
• In 2005 and 2006 our premium aggregates is coming
  from as far away as Whitcourt, Nordeg and Rocky
  Mountain House some 220 to 270 km from Edmonton

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Other Issues

• In 2005 we had a cement shortage, resulting
  delays in project completions
• Also in 2005 the Independent truckers went on
  strike Net result was an increase in trucking
  costs, increase in project costs and delays in
  project completion
• In 2006 we had an Asphalt Cement shortage,
  resulting in project delays
• Manpower issues, with the hot construction market
  in Alberta it is becoming much more difficult to
  attract workers

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GENERAL ROAD STRUCTURES IN EDMONTON
Granular/ Soil Cement (63 of Network)
Deep Strength Asphalt or Oil Mix ( 10 of
Network)
Composite Pavement ( 27 of Network)
50 - 250mm Hot Mix Asphalt
100-150 mm Hot Mix Asphalt
200-300mm Hot Mix Asphalt or Oil Mix
150 - 300mm Granular Base or Soil Cement Base
150-200mm Portland Cement Concrete
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Historical Overview of Asphalt Mixes
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Specialty Mix Initiatives
Since the mid 1970s, the City of Edmonton has
been involved with trials utilizing a variety of
Hot Mix Asphalt specialty mixes

• Asphadur (1980 1981)
• Sulphur-Modified Asphalt (1981)
• Polymer Modified Binders (1986 Present)
• Stone Mastic Asphalt SMA (2000-Present)
• Asphalt Rubber (1976, 2002-Present)
• Superpave (1999, 2001-2002)

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Polymer Modified Binder Usage
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SMA, Stone Mastic Asphalt

• SMA 16mm, 50 Blow Marshall Surface Mix (Overlay
  and Surface Mix on Higher Traffic Volume
  Roadways)

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Advantages/Disadvantages

• Advantages of SMA
• SMA provides durable, and rut resistant wearing
  course
• Mix surface texture characteristics are such that
  noise generated by traffic is lower than dense
  graded mixes (measured at 4 decibels quieter)
• Can be placed and compacted with conventional
  paving and rolling equipment
• May provide reduced reflective cracking from
  underlying cracked pavements due to the flexible
  mastic.

• Disadvantages of SMA
• Aggregate costs, bringing in high quality
  aggregate from Whitecourt, Nordeg and Rocky
  Mountain House
• Higher Binder costs with the use of the polymer
  modified binders

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Yellowhead Trail East of 50 Street (2006)
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66 Street Yellowhead Trail (2004)
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(No Transcript)
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Rutting Performance
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Asphalt Rubber
Asphalt rubber mix is a gap graded 12.5mm, 75
blow Marshall surface asphalt mix containing 18
crumb rubber particles and 82 AC 80-100
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Advantages/Disadvantages

• Advantages of Asphalt Rubber
• Asphalt Rubber provides a textured and rut
  resistant wearing course
• Surface texture characteristics are such that
  noise generated by traffic is lower than dense
  graded mixes 4-8 decibel reduction depending on
  the roadway
• Can be placed and compacted with conventional
  paving and rolling equipment

• Disadvantages of Asphalt Rubber
• Aggregate costs, aggregate processing is similar
  to an SMA mix resulting in additional processing
• Higher Binder costs due to the increase quantity
  of binder required in the mix and blending
  equipment
• Cost of Crumb rubber component
• Surface of mix requires a solution of lime water
  to be applied prior to trafficking

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Stony Plain Road (2003)
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50 Street South of 13 Avenue (2003)
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153 Avenue East of 66 Street (2006)
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Superpave
Our Superpave mix is a 12.5mm Superpave Course
surface asphalt mix with a PG 58-34 binder with a
design traffic loading of lt3X106 ESAL's.
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Advantages/Disadvantages

• Advantages of Superpave
• Mix is designed for anticipated traffic loadings
• Longer pavement life, with less fatigue and
  thermal cracking,
• Can be placed and compacted with conventional
  paving and rolling equipment

• Disadvantages of Superpave
• Aggregate costs, additional aggregate processing
  results in additional costs
• Additional mix costs due to PG testing of Binder
• Some difficulty in placement of mix due to mix
  tenderness

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Winterburn Interchange on Yellowhead Trail (2002)
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Other Initiatives

• Full Depth Reclamation using Foamed Asphalt
• Infrared Thermography Studies
• Use of Ground Penetrating Radar for structural
  evaluation of roadway structures

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Full Depth Reclamation Utilizing Foamed Asphalt
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Advantages of Full Depth Reclamation with Foamed
Asphalt

• Reuse of the material in the existing
  pavement generally better quality materials than
  are currently available.
• Derive maximum benefit of existing pavement
  structure as a stabilized base course material
• Simultaneous addition of make-up (granular)
  material and/or stabilizing agent(s)
• Speed of construction - one or two pass
  operation vs. a multi-pass operation
• Accommodation of traffic - roadway is never
  closed to traffic
• Economics () 30 to 50 saving

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150 Avenue East of 94 Street (2001)
12/10/2006
12/10/2006
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Ellerslie Road 50 Street (2003)
12/10/2006
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150 Avenue Deflection Performance
150 Avenue, 87 Street to 94 Street
3.5
3.3
3.0
2.8
2.5
2.3
2.0
1.8
Deflection (mils)
1.5
1.3
1.0
0.8
0.5
0.3
0.0
0000
0040
0090
0140
0190
0240
0290
0340
0390
0440
0490
0540
0590
0640
0690
0740
0790
0840
Station
May -06
Pre - 2001
Post - 2001
Aug -02
May-05
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Infrared Thermography

• cold spots thermal segregation results in poor
  performance

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Ground Penetrating Radar
Asphalt on Soil Cement Base
Asphalt on Concrete on Granular Base
Asphalt on Soil Cement Base
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Where Do We Go From Here?

• Trial project utilizing warm asphalt technology
• Cold-in-Place Recycling of existing road
  structures
• Study on our current Hot-Mix Asphalt mixes with
  respect to the incorporation of RAP