Imants Deme

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Canadian User-Producer Group for Asphalt CUPGA
2007, Sustainability Symposium November 18, 2007
Reducing the size of the asphalt ecological
footprint with SEAM (Sulphur Extended Asphalt
Modifier)
Presented by Imants Deme Shell Sulphur
Solutions Shell Canada Energy
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Contents

• Sulphur-Extended Asphalt history
• SEAM properties and use
• Health, safety and environment
• SEAM technology (40/60 SEAM/bitumen
  semi-rigid pavements)
• - Bitumen reduction
• - Road performance properties
• - Road design
• The green page
• Examples of applications

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SEAM history
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Historical perspective
Pelletized sulphurwith dispersing agent, H2S
scavenger plasticizer Sulphur-Extended Asphalt
Modifier SEAM
Liquid sulphur High shear mixer No H2S
scavenger no plasticizer
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SEAM properties and use
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SEAM Properties

• Solid pellet at ambient temperatures (lt5 mm)
• Easy to add to asphalt hot-mix
• Melts quickly in hot-mix
• Can be stored on ground or in silos
• Additive advantages
• - disperses sulphur in bitumen
• - reduces odour gas emissions
• - plastification agent

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Health, safety, environment
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SEAM Mix Fume Emissions (Six Hour Average)
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ASPHALT HOT-MIX PLANT H2S SO2 0 AT MIXER AND
TRUCK LOADING AREA (SHOWN BY ARROW)
ASPHALT PAVER H2S
S02 ABOVE SCREED (1) 0.9 PPM
0 PPM OPERATOR PANEL (2) 0.1 PPM 0.3
PPM AVERAGE LIMIT (2002 TLV) 10 PPM 2
PPM
INDUSTRIAL HYGIENIST CONCLUSION NO BREACH OF
COMPLIANCE FOR EMPLOYEE EXPOSURE
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Stack emissions not increased
Gencor Plant, 300 tph capacity
Conclusion No significant difference in SO2
H2S emissions and lower hydrocarbon emissions for
SEAM mix
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VOC reduced by 50
SUMA vacuum canisters used in study
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SEAM technology

• Bitumen reduction
• Strength properties
• Road design

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SEAM PG Performance based on Marshall
SEAM addition to asphalt mix increases Marshall
Stability and has the same effect as using
modified bitumens which are from 1.8 to 3.6 PG
grades higher
PG70-22 SEAM
?
PMA
PMA
In semi-rigid mix (40SEAM/60Bitumen)
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Marshall Stability 2-3 PG grade increase
300/400 200/30 150/200 80/100
59 Pen PMB PMB
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APA Wheel Rutting (After 8000 wheel passes)
   
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SEAM modulus is less temperature sensitive
Temperature, ?C
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Thick SEAM pavements may prolong road life
msa millions standard axles
Asphalt or SEAM Pavement thickness
300mm gran. base sub-base
sub-base sub-base
Predicted road life increases with pavement
thickness SEAM may provide exceptionally longer
road lives when used in thick pavements
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Restrained Specimen (TSRST) Cooling Test
MIX PG52-34 SEAM COOLING RATE -10 ?C/h
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Addition of SEAM to asphalt mix does not change
pavement resistance to cracking at low
temperatures
 
PG46-34 PG52-34
PG58-28 PG64-22
PG58-28 300/400
200/300 150/200
80/100 80/100
NB Mix cracking temperature within 2.4 C of
bitumen PG low temperature value
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Uses for which SEAM is particularly suited

• Heavy duty use heavy duty pavements, high
  traffic intersections, bus lanes, truck climbing
  lanes, truck terminals, airfields, container
  terminals
• Upgrades quality of mixes made with poor
  aggregates
• - Rut resistant mixes from fine-graded (sandy,
  marginal) aggregates
• - Aggregate conservation reduces amount of
  stone required to be crushed to make angular
  fines (important in aggregate-scarce areas)
• - Safeguard against premature rutting for
  pavement sections which were under-compacted
  during construction
• The combination of high rut resistance, constant
  stress fatigue resistance (road life) higher
  modulus (load spreading), makes SEAM mixes
  particularly suitable for thick long life
  perpetual pavement designs
• Prevents pavement cracking in cold climate areas
  without compromising resistance to rutting of
  pavements
• Improves performance of mixes made with poor
  quality (e.g. waxy) bitumens (i.e.resistance to
  rutting and cracking)

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The Green Page Advantages from SEAM use

• Energy Cost Saving (approx. 5 direct 11
  indirect)
• - Less bitumen to heat
• - Lower mix temperature (ie. 1/3 way to warm
  mix)
• - Lower plant fuel consumption
• - Significantly lower fuel consumption relative
  to PMA
• Conservation of Hydrocarbon Resources
• - Conserves fuel bitumen
• Conservation of Aggregate Resources
• - Permits use of fine-graded (marginal, sandy)
  aggregates
• - Stability of sand-asphalt mixes increased
  significantly
• Environment
• - Reduces VOCs (volatile organic constituents)
• - Use in roads provides sulphur producers with a
  sustainable application for unmarketable sulphur
  
• - Provides a carbon credit (bitumen
  reduction/lower energy, etc.)

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Summary of SEAM-specific issues

• Feeder required for adding SEAM pellets
  accurately
• Strict temperature control is required during
  SEAM mix processing
• SEAM mixes emit more odor, fumes, and eye
  irritant than conventional asphalt mix during mix
  placement
• (NB SEAM use complies with regulatory
  exposure requirements)
• More difficult to recycle hot

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High stress intersection
Storage terminal parking lot
Vancouver, Canada
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Las Vegas, USA SEAM wearing base course
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Port of Oakland, California 300mm SEAM pavement
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Yunnan, China Tollway SEAM base course with SMA
top course
Nantong Port, China storage terminal
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Kazakhstan SEAM pavement
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Saudi Arabia SEAM test road
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Reducing the size of the asphalt ecological
footprint
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Calgary, Canada SEAM wearing course