Solving Problems | Quality Control | How it is made & applied | Cost Savings | Benefits
What is Micro-Surfacing?
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 of both urban and rural roads, Micro-Surfacing has many 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 1960's and early 1970's. 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 thickness, 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.
|Solving Problems with Micro-Surfacing
- 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 (9.5 mm), Micro-Surfacing can increase skid resistance, color contrast, surface restoration, and service life to high-speed, heavy-traffic roadways (Instate, and Autobahns). Such projects are often reopened to traffic within an hour.
- Modern, continuous-load pavers can lay 500 tons of Micro-Surfacing per day, with no long traffic delays. This equates to an average 6.6 lane miles (10.6 lane kilometers) per day for surfacing applications.
- On airfields, dense-graded Micro-Surfacing produces a skid resistant surface without loose rock that damages aircraft engines.
- As a thin, restorative surface course on urban arterials and heavy traffic intersections, Micro-Surfacing does not alter drainage; there's 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 for use.
- Because Micro-Surfacing can be effectively applied to most surfaces at 3/8 inches (9.5 mm) or less, more area per ton of mix is covered, resulting in cost-effective resurfacing.
- 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 surfaces (usually preceded by a tack coat on concrete), Micro-Surfacing is often used to restore a skid resistant surface to a 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 temperatures and weather conditions, effectively lengthening the paving season. It is particularly suitable for night applications on heavy-traffic streets, highways, and airfields.
- Applied at ambient temperature, Micro-Surfacing has low energy requirements. And it is environmentally safe, emitting no pollutants.
- Micro-Surfacing's life expectancy usually exceeds seven years.
- Capable of filling wheel ruts up to 1-1/2 inches (38 mm) 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.
|Micro-Surfacing Quality Control
Micro-Surfacing is a versatile product, it cannot solve all pavement problems. Here is a brief overview of problems that must be dealt with correctly in order for Micro-Surfacing to perform properly.
|Fix before Micro-Surfacing
||Micro-Surfacing can correct
||Asphalt patch area
|Pushed up edge line (cold mill)
Problems to watch for after the Micro-Surfacing project:
- Surface drag marks
- Breaking too quickly
- Contaminates on road
- Unacceptable transverse joint
- Under filled rut work
- Unacceptable patch work
- Early traffic crossing
|How is Micro-Surfacing Made and Applied
Micro-Surfacing is made and applied to existing pavements by a specialized machine, which carries all components, mixes them on site, and spreads the mixture onto the road surface.
materials are continuously and accurately measured, and then thoroughly combined in the Micro-Surfacing machine's mixer.
As the machine moves forward, the mixture is continuously fed into a full-width "surfacing" box which spreads the Micro-Surfacing across the width of a traffic lane in a single pass. Or specially engineered "rut" boxes, designed to deliver the largest aggregate particle into the deepest part of the rut to give maximum stability in the wheel path, may be used. Edges of the Micro-Surfacing are automatically feathered.
The new surface is initially a dark brown color and changes to the finished black surface as the water is chemically ejected and the surface cures, permitting traffic within one hour, in most cases.
- Aggregate Bin
- Mineral Filler Bin
- Additive Storage
- Metered Micro-Surfacing Emulsion
- Metered Aggregate
- Metered Water & Additive
- Pug mill
- Surfacing Spreader Box
- Brown to Black Color
- Road Water Spray bar
|Continuous-load pavers utilize support units which bring the materials to the job site and load the machine while it is working, thus maximizing production and minimizing transverse joints.
|Preventative Maintenance Cost Savings
Even the best of surfaces are subject to the wear and tear caused by time, weather and traffic. No surface is permanent.
By undertaking a program of planned pavement maintenance, major savings in rehabilitation costs may be achieved, as shown in the graph below.
The application of the proper asphalt slurry system (Micro-Surfacing and/or slurry seal) will significantly extend the life of existing pavements by protecting the undersurface from damage caused by water seepage and oxidation. Improved surface performance is also achieved.
A pavement maintenance program using slurry systems will not only help protect your pavement - it will help to protect your paving investment.