Pavements - PowerPoint PPT Presentation

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Pavements

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Concrete Concrete Rigid pavement Used where strength is an issue ... highest form of asphalt pavement Can be used as soon as compacted and cooled to ambient ... – PowerPoint PPT presentation

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Title: Pavements


1
Pavements
2
Concrete
  • Concrete
  • Rigid pavement
  • Used where strength is an issue
  • Runways, interstates and major roads
  • Continuous reinforcing
  • Must have a good base and joints and cracks must
    be sealed
  • Long life 50 years
  • Major rehab is a major problem

3
Concrete
  • Forming and pouring
  • Old way set forms and have equipment ride the
    forms
  • Paving train mix, place, finish, cure all in
    one train of equip
  • Standard forms 10 ft long 8 12 inches deep
  • New Way
  • Slip form, Use 0 slump concrete
  • Machine pulls form with it slab comes out
    finished
  • F 8-1, 8-2

4
Concrete
  • Roller Compacted Concrete
  • Dam construction, landfills
  • 0 slump concrete is placed on a site and
    compacted w/vibratory roller
  • Higher strength, low air entrainment

5
Asphalt
  • Bituminous
  • Bituminous distributor
  • F8-4
  • Used on all types of bituminous construction
  • Application rate depends on spray bar length,
    travel speed, pump output
  • Control by bitumeter
  • S (9xP)/(WxR)
  • S road speed, P pump output, W spraybar
    width, R application rate

6
Asphalt
  • Surface treatments
  • Prime coat goes on unpaved surface
  • Provides waterproofing and wear surface
  • 0.25 0.5 gal/sq. yd.- cures in 24 48 hours
  • Tack coat goes on a paved surface to act as
    bonding agent
  • 0.1 gal/sy quick cure
  • Dust pallitive keeps dust down for 30 days
  • Fog seal slow setting, 1-3 parts water
  • Emulsion slurry sealer driveway sealer
  • Sand seal fine aggregates and asphalt

7
Asphalt
  • Single pass treatments
  • Spray bitumin
  • Cover with aggregate 1 stone deep
  • 25 30 of aggregrate/sy
  • 0.25- 0.3 gal/sy binder
  • Sweep surface
  • Apply prime coat, cure
  • Apply binder
  • Apply aggregate
  • Roll surface
  • Sweep to remove loose stone

8
Asphalt
  • Multi pass treatments
  • Spray bitumin
  • Multiple single pass treatments
  • 25 30 of aggregrate/sy
  • 0.25- 0.3 gal/sy binder
  • Each layers aggregate is ½ size of previous layer

9
Asphalt
  • Asphalt Paving
  • Hot mix high type pavements
  • Cold mix patching
  • Penetration macadam old way of paving
  • Place and compact 4 of coarse aggregate
  • Cover with asphalt binder and a smaller aggregate
    (key aggregate) and rolled
  • Cover with asphalt binder and a smaller aggregate
    (key aggregate) and rolled

10
Asphalt
  • Road Mix
  • Mixed on roadway
  • Grader, rotary mixer, travel plants
  • Hard to get a consistent result

11
Asphalt
  • Hot Mix (HMA) highest form of asphalt pavement
  • Can be used as soon as compacted and cooled to
    ambient temp
  • Flexible, frost resistant
  • Cold mix like hot mix
  • Advantages can haul long distances, stockpile,
  • Disadvantages slow curing, low initial
    stability, difficult to compact in cold weather

12
Asphalt
  • Hot mix paving operations
  • Delivery of asphalt mix,spreading and compaction
  • Spreader couples with the delivery truck and
    pushes it along as asphalt is unloaded
  • Spreader spreads and compacts
  • Spreader consists of pusher unit and screed unit
  • Spreaders control depth and width of pavement
    using laser, stringline, shoe to control screed
    elevation

13
Asphalt
  • Towed pavers smaller jobs usually driveways
  • Max width 10 ft
  • Large paver
  • To lay a 3 deep, 12 ft wide, strip at 50 ft/min
    need 600 tons/hr of asphalt

14
Asphalt
  • Compacting immediately after spreading
  • Breakdown rolling provides initial compaction
    - static steel rollers with drive wheel forward
  • Intermediate rolling pneumatic rollers better
    surface sealing
  • Finish rolling tandem steel rollers final
    compaction

15
Asphalt
  • Superpave
  • Developed due to asphalt concrete failures
  • Uses lower asphalt content ,crushed stone and
    optimizes for local conditions- NYS thruway uses
    7 different mixes

16
Repair and Rehab
  • Highways
  • Resurface, restoration, rehabilitation and
    reconstruction 4Rs
  • Resurfacing surface treatments, overlays,
  • Restoration and Rehab return highway to
    acceptable condition
  • Planning or milling top layer , fixing lower
    level, repave
  • Reconstruction complete redo of roadway

17
Repair and Rehab
  • Recycling pavement
  • Concrete is broken up and sent to a recycling
    plant which removes steel and crushes concrete
    into aggregate
  • Asphalt is milled and recycled in an asphalt
    plant F- 8-108-11
  • HMWK Ch 7 2,3,9 Ch 8 5,7,9
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