Presentation by DengXin Cheng and Gary Hicks of California State University, Chico Pavement Preservation Center on the topic of pavement preservation delivered at the CalAPA Fall Asphalt Pavement Conference Oct. 24, 2013 in Sacramento, Calif.
2. Overview of Presentation
• Types of Treatments
–
–
Materials Used
Design & Construction
Considerations
– Causes of problems
• Factors Affecting
Performance
• Strategy Selection Process
Most of this work has been supported by Caltrans
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5. Types of Preservation Treatments
• Fog and Rejuvenating
Seals
• Chip Seals
• Slurry Seals
• Microsurfacing
• Cape Seals
• Bonded Wearing Courses
• Thin HMA overlays
• CIR and HIR
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6. Fog and Rejuvenating Seals
• Purpose- enriches dry pavement
surfaces, reduces raveling, and
locks in chips on chip seals
• Materials- generally diluted asphalt
emulsions or a specialty product
• Design considerations- application
rate a function of surface condition
• Construction- applied using a
distributor truck in diluted form
• Expected life - 1 to 3 years or more
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7. • Using excess emulsion for the
existing pavement surface
• Placing in wet and/or cool weather
• Over or under dilution
• Incompatible water for dilution
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8. • Purpose- waterproof the existing
surface and improve texture. Can
also serve as an interlayer
• Materials- application of emulsions
or hot binders followed by clean
aggregate
• Design- application rates need to
be determined
• Construction-asphalt is applied
followed by an application of
aggregate. May be used in multiple
layers
• Expected life- 5-7 years or more
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10. •
•
•
•
Improper surface preparation
Applying in cool and/or wet weather
Using dirty rock
Not accounting for new patches or flushed
surfaces
• Not taking traffic into account
• Over spreading or under spreading binder or
aggregate
• Application on unsound pavements
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12. • Chip seal with a polymer modified
rejuvenating emulsion (PMRE)
• A scrub broom is used to push the emulsion
into the cracks
• Rejuvenates as it seals the pavement surface
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16. • Purpose- Seals minor cracks, restores
surface texture, mitigates raveling
• Materials- a mixture of graded
aggregate, asphalt emulsion (generally
polymer modified), and setting agents
• Design considerations- special mix
design is needed
• Construction-applied using a special
paver mounted on a truck
• Expected life- 5 to 7 years or more if
placed on sound pavements
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19. • Improper surface preparation or
placing on unsound pavements
• Place in cool and/or wet weather
• Not requiring a mix design or
calibrating the equipment
• Aggregate grading out, especially
in fines content
• Too much or too little additive
• Improper maintenance of spreader
box and drag
• Adding too much water
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21. • Purpose- seal the surface, fill wheel ruts and minor
surface irregularities, and can be placed at night
• Materials- a mixture of graded aggregates, polymer
modified emulsion, and set additives
• Design considerations- requires a mix design to
determine the proportion of components
• Construction- applied using a special truck mounted
mixing/paving machine. For long straight jobs a
continuous machine is recommended
• Expected life-last 8-12 years depending on the surface it
is applied too
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24. • Improper surface preparation or placing on
badly cracked pavements
• No mix design
• Construction in wet weather
• Truck mounted equipment placing improper
joints
• Too much hand work
• Too much overlap on joints
• Too much water in the mix causing segregation
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26. • Purpose- seal the surface and provide a
smooth hard wearing surface
• Materials- a chip seal followed by a slurry
seal
• Design considerations- mix designs for
both products
• Construction- application of a chip seal
followed by a slurry seal
• Expected life- 8-12 years or more
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29. •
•
•
Improper surface preparation
No mix designs
Applying in cool and/or wet
weather
• Over application of binder in
either course
• Using conventional chip seal
or polymer modified chip
seals over cracked surfaces.
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30. Thin Bonded Overlays
• Application of
polymer modified
binder immediately
followed by a thin hot
mix overlay
• Total thickness has
been about 25 mm
• Applied with a spray
paver
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31. Thin HMA Overlays
• Types
– Conventional
– Polymer modified
asphalt
– Asphalt rubber
– Terminal Blend
• Thickness 1-1.5
inch
• Used with warm
mix additives
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32. Factors Affecting the Performance of
Pavement Preservation Treatments
• Existing pavement
condition
• Construction process
and workmanship
• Materials quality and
selection
• Climate and Traffic
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33. Pretreatment Pavement Condition
Fair
Poor
36%
64%
Standard
Deviation
18%
18%
Materials Selection and Quality
Marginal
Poor
36%
57%
22%
20%
Construction and Workmanship
Marginal
Poor
45%
61%
21%
21%
Mix and Structural Design
Marginal
Poor
35%
57%
19%
20%
Medium
Poor
22%
45%
22%
25%
Marginal
Poor
33%
50%
24%
24%
Treatment Life Reduction Percentage, % Average
Traffic Level
Climate during and immediately
after construction
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38. Advantage of the Preliminary
Developed Expert System
• Uses Caltrans MTAG existing decision
matrix
• Can deal with more complex scenarios
• Knowledge is retained to the system
• New treatments can be added
http://ceresearch.ecst.csuchico.edu/TreatmentSelection2.0/V
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39. • Types of Surface Treatments
–
–
–
Design and construction considerations
Expected performance
Causes of problems
• Factors Affecting the Performance of
Preservation Treatments-FHWA study
• Strategy Selection Process Using Life
Cycle Cost
39
{"38":"Uses Caltrans MTAG existing decision matrix as first step to narrow down answers\nCan deal with more complex scenarios than common decision tree or decision matrix\nKnowledge is retained to the system\nNew treatments can be added to the system fairly easy without overhaul the whole structure (tree or matrix)\n","12":"Base asphalt\nSolvent-free rejuvenating agent\nHigh quality emulsifier\nTough Polymer\nPASS Components are sourced from the best in the industry. The polymer has been specifically formulated for PASS. is unique in that it is the only chip retention emulsion with a rejuvenating agent added. \n","14":"There are three factors that need to be addressed when using the Boom:\nEnough emulsion to retain the chips.\nEnough Emulsion in the wave to fill the cracks. This a function of crack intensity\nYou do not want emulsion to flow outside the broom head. In this case re reduced the spray width and compensated by rate adjustment.\n","4":"Changed wording to add “corrective maintenance”\nEFFECTIVE PREVENTIVE MAINTENANCE\nMany states as well as the federal highway administration have found that doing preventive maintenance is 3 to 10 times more cost effective than a do nothing strategy.\n"}