Micro-surfacing was pioneered in Germany in the late 1960s and early 1970s. 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. It is now recognized as not only the most cost-effective way to treat the surface wheel-rutting problem, but also a variety of other road surface problems. Used throughout Europe, the United States and Australia, micro-surfacing is making inroad into many other areas.
One of the most versatile tools in the road maintenance arsenal, Micro-surfacing is polymer modified cold-mix paving system that can remedy a broad range of problems on today’s streets, highways and airfields. It 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 owing to use of high-quality carefully monitored materials, including advanced polymers and other modern additives.
As a surface treatment, micro-surfacing imparts protection to the underlying pavement and provides renewed surface friction values. Special emulsifiers in micro-surfacing emulsions contribute quick setting characteristics. Formulations are required under average conditions to allow the return of straight running traffic to the surface in one hour. Minor re-profiling can be achieved with multiple applications. Special equipment permits the filling of wheel ruts up to 40 mm deep in one pass.
- Quick-set, quick-traffic
- Chemical break permits night time application
- Suitable for use on high traffic volume, limited access highways
- Single pass application rates of 11 to 16 Kgs./sq.m. yielding micro-surfacing depths from 9 to 16 mm in depth
- Scratch course followed by a finishing course provides minor re-profiling and a new riding surface
- Rut filling followed by a finishing course provides proper water drainage
Recommended Product and Rate of Application: Normally used emulsion for micro-surfacing is MARUTI Micro-S Emulsions and rate of application of 10.0 to 14.0% of total aggregate.
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 mix 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 colour 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. 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.
Using various design mixes, techniques and equipment, Micro-surfacing can be used successfully in the following situations:
- In quick-traffic applications as thin as 3/8 inch (9.5 mm), Micro-surfacing can increase skid resistance, colour contrast, surface restoration and service life to high-speed, heavy-traffic roadways. 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.
- 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 crates 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 two 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.
Problems to watch for after the Micro-surfacing project
- Surface drag marks
- Breaking too quickly
- Contaminates on road