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Seal Coating

Asphalt seal coating is a broad term used to describe several types of asphalt-aggregate applications, usually less than 25mm thick and applied to any kind of road surface. The road surface may be primed, granular base, or an existing asphalt or Portland cement concrete pavement. The treatments can be placed in one or more lifts in combinations of types. Available raw materials, cost and treatment life cycle will have a large impact on the process chosen.

Features & Benefits:

  • Emulsions can be used with damp aggregate, which is actually preferred
  • Environmentally friendly process, do not need elevated temperatures
  • Emulsions are low emissions eliminating fire hazards and air quality problems associated with cutbacks
  • Custom formulas for existing environmental conditions and available aggregates
  • Polymer modified emulsions can be used to enhance asphalt properties for; durability, stability impermeability, early stone retention and reduces flushing and bleeding
  • Renews weathered pavements
  • Improves skid resistance, available in various textures
  • Fine aggregate treatments can improve street sweeping
  • Reduces ravelling
  • Restores a uniform cover
  • Prevent the intrusion of moisture and air
  • Seals very small cracks and surface voids
  • Enriches and coats weathered aggregate particles at the surface
  • Delineate shoulders from traffic lanes

Chip Seals – Presentation

A chip seal is commonly referred to as a seal coat that is primarily made up of one size aggregate that can be either washed or dusty. The aggregates can range in size from 19mm to 4.75mm. Generally, the largest particle should be no more than twice the diameter of the smallest one. Aggregate gradation and type will dictate application rates for the aggregate and emulsions along with the type of emulsion.

Graded Aggregate Seals

A graded aggregate seal is defined as a seal coating using a well-graded aggregate rolled into a high float emulsified asphalt, sometimes referred to as a dense graded seal. A typical gradation is 98% less than 16mm with 2-7% passing the 75mm sieve. Aggregate gradation will determine application rate of the emulsion.

Sand Seals

A sand seal is a spray application of asphalt emulsion followed with a light covering of fine aggregate, such as a clean sand or screenings. Although this is a simple operation, it can be useful in correcting a number of pavement flaws. Emulsion is usually sprayed between 0.70 to 1.25 l/m2 and sand is placed at 5.5 to 12 kg/m2 as a cover.

Fog Seals

A fog seal is a light application of asphalt emulsion to an existing paved asphalt surface. This type of maintenance treatment is primarily employed as an impervious sealer that will slow the rate of weathering of the asphalt in the underlying pavement.