Extend the Pavement Life-cycle with Micro-surfacing
Micro-surfacing is a surface treatment that’s been in use since the 1970’s. It was originally used in Europe to fill ruts on the Autobahn. It is now widely implemented as a high friction surface treatment to protect existing asphalt, extend the life of roads, streets and highways, and reduce overall maintenance costs.
Micro-surfacing is a combination of emulsion, aggregates, water, and additives. These elements are mixed and then applied at ambient temperature to the existing asphalt. The thickness of the micro-surfacing application is approximately 3/8 of an inch, or equal to the size of the aggregate that is used in the mix design. Micro-surfacing is typically applied in lifts which consists of several coats or passes. It can also be used to fill ruts of up to 2 inches. Micro-surfacing mix is sometimes referred to as a polymer-modified slurry seal.
Because micro-surfacing is generally classified as a preventative maintenance treatment as opposed to a corrective maintenance treatment, the condition of the asphalt surface must be in relatively good condition. Pavement condition should be 6 or better on a scale of 1-10, with 10 being new asphalt.
When installed, micro-surfacing seals the asphalt below, restores the friction, prevents water from entering the base, prevents further oxidation and provides a wearing surface which should last 7 to 10 years. When needed, another surface coat of micro-surfacing can be applied.
Cities, counties and departments of transportation throughout the United States have realized the value and benefit of micro-surfacing. When micro-surfacing is applied as a part of a pavement preservation strategy, it can extend the life of the asphalt base by 40 or more years, for a fraction of the maintenance cost. (Insert graph.)
Considerations:
- Asphalt must be in good condition
- Cracks need to be filled with a high-performance crack-filler
- Road surface should be fee of dirt and debris
- Pavement repairs should be made in advance of applying micro-surfacing
- Pavement markings may need to be removed
Benefits:
- Easy to install
- Traffic can be restored in approximately an hour
- Low cost – high return – costs 30% less than hot mix asphalt (HMA) overlays
- *International Slurry Seal Association (ISSA) reports micro-surfacing costs $17,600 per lane mile, while milling and HMA cost $50,000 per lane mile.
- Seals pavement
- Restores friction
- Extends pavement life – treatments can last 7 to 10 years
- Corrects ruts
- Can be installed in several lifts
- Can be used to seal centerline joints
- Can be installed on top of chip & seal surfaces
