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Why Choose Concrete Overlay’s over Asphalt Replacement?

Asphalt parking lots serve many different types of businesses with light to high traffic areas.   Let’s explore an outline for parking lot owners that include concrete overlay to existing asphalt. 

Investigating the reasons behind the asphalt deterioration. Some examples why asphalt deteriorates:

  • Age
  • Poor Drainage
  • High traffic/Usage
  • Subgrade conditions
  • Poor construction
  • Inadequate mixtures
  • Substandard materials

Concrete over Asphalt is:

  • Durable
  • Low maintenance
  • Long life parking structure
  • In many circumstances concrete overlay is ready for traffic within 24 hours
  • Easy to repair
  • Fiber reinforcement is not necessary in concrete overlays supporting cars and light trucks
  • The recommended joint pattern for overlays of asphalt are small square panels that range from 4 to 6 feet
  • Bonded overlay are normally “thinner” than new pavements which reduces cost
  • In most situations there are no pre-overlay repairs to existing asphalt since the overlay will fill in and “absorb” loose asphalt
  • Less night lighting needed in parking lots due to high reflective surfaces
  • Absorb less heat energy on hot days which has a dramatic effect on surface area heat absorption
  • Improves pedestrian and vehicle visibility due to higher reflective qualities

Overlays have bonded and un-bonded options:

  • Bonded Overlay Recommendation: Bonds with existing pavement to essentially form a single block of “stone” for low to medium asphalt damage
  • Un-bonded Overlay Recommendation: New concrete that uses the existing asphalt as the base for high asphalt damage

Assessment during the design process is important:

  • Where are the access ways
  • Are there truck lanes or loading docks
  • Vehicle size utilizing the parking lot
  • Elevation issues and transitions
  • Where new overlay will meet the existing asphalt that isn’t part of the design
  • Is the existing asphalt structure stable? Example… Subgrade soil
  • Identify the existing asphalt cross section and condition.  There must be strength and integrity since it will function as part of the overlay.
  • Identify future goals of the parking lot
  • Drainage survey
  • Evaluation of site limitations
  • History of repairs on existing asphalt
  • Traffic measurements
  • Moisture related distress
  • Core analysis

Types of Asphalt distress(See Diagram):

  • Alligator cracking
  • Raveling
  • Cracking
  • Rutting
  • Shoving (Slippage)
  • Potholes/Pop outs
  • Grade Depressions

Types of Asphalt Distress

 

Types of Curb Detail. Curb can be capped or milled as part of the Overlay Design:

Types of Curb Detail

Types of Equipment & Techniques used while Overlaying Asphalt

  • Hand/Wet Screeding
  • Handheld vibratory screed
  • Roller screeds
  • Vibratory truss screeds
  • Laser screeds
  • Slipform paving
  • Sawing concrete overlays

 

 

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