One of the most versatile tools in the road maintenance arsenal, Micro-surfacing is a polymer-modified cold-mix paving system that can remedy a broad range of problems on today’s streets, highways, and airfields.
Like its parent product, slurry seal, Micro-surfacing begins as a mixture of dense-graded aggregate, asphalt emulsion, water, and mineral fillers. While conventional slurry seal is used around the world as an economical treatment for sealing and extending the service life of both urban and rural roads, Micro-surfacing has added capabilities, thanks to the use of high quality, carefully monitored materials, including advanced polymers and other modern additives.
Micro-surfacing was pioneered in Germany in the late 1960s and early 1970s. German scientists began experimenting with conventional slurry to find a way to use it in thicker applications which could be applied in narrow courses for wheel ruts, and not destroy the expensive road striping lines on the autobahns.
When the scientists used highly selected aggregates and bitumen, and then incorporated special polymers and emulsifiers that allowed the product to remain stable even when applied in multi-stone thicknesses, the result was Micro-surfacing.
Introduced in the United States in 1980, Micro-surfacing now is recognized not only as the most cost-effective way to treat the surface wheel-rutting problem, but also a variety of other road surface problems. Micro-surfacing is now used throughout Europe, the United States, and Australia and is making inroads into many other areas.
Micro-surfacing can be an effective wear course for other asphalt recycling techniques such as Cold In-place (CIR) and Hot In-place (HIR) Recycling. When we consider Micro-surfacing has a 7-10 year life extension, and the recycling process prolong the crack mitigation process two fold, it is conceivable that a Micro-surfacing/Hot In-place recycling project may add 12-15 years of service life to an existing roadway with proper preventative maintenance techniques.
Using various design mixes, techniques, and equipment, Micro-surfacing can be used successfully in these situations:
- In quick-traffic applications as thin as 3/8 inch (9.5mm), Micro-surfacing can increase skid resistance, color contrast, surface restoration, and service life to high-speed roadways (interstates and autobahns). Such projects are often reopened to traffic within an hour.
- On airfields, dense-graded Micro-surfacing produces a skid-resistant surface without loose rock that damages aircraft engines.
- As a thin, restorative surface source on urban arterial and heavy traffic intersections, Micro-surfacing does not alter drainage; there is no loss of curb reveal.
- Micro-surfacing is applied to problem sections of roads or runways to eliminate hydroplaning problems that occur during periods of rain. The Micro-surfacing restores the proper surface profile and makes the area safe to use.
- Because Micro-surfacing can be effectively applied to most surfaces at 3/8 inches (9.5mm) or less, more area per ton of mix is covered, resulting in cost-effective surfacing.
- Micro-surfacing creates a new, stable surface that is resistant to rutting and shoving in summer and to cracking in winter.
- Applied to both asphalt and Portland cement concrete surfaces (usually preceded by a tack coat on concrete), Micro-surfacing is often used to restore a skit-resistant surface to slick bridge decking with minimum added dead weight.
- Used as a scratch (leveling) course, to be followed by a surface course, Micro-surfacing can provide transverse surface leveling.
- Because of its quick-traffic properties, Micro-surfacing can be applied in a broad range of temperature and weather conditions, effectively lengthening the paving season. It is particularly suitable for night application on heavy-traffic streets, highways, and airfields.
- Applied at ambient temperatures, Micro-surfacing has low energy requirements. And it is environmentally safe, emitting no pollutants.
- Capable of filling wheel ruts up to 1-1/2 inches (38mm) deep when the pavement has stabilized and is not subject to plastic deformation, Micro-surfacing has the unique ability to solve this problem without milling.