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

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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