The humble chip seal and other road surface treatments that use asphalt emulsions are being taken to new heights by a variety of modifiers that enhance performance, albeit at a higher price.
Thus polymer-modified asphalt emulsions can improve performance to the point that with the right design, they can challenge hot-mix asphalt as an overlay option for high-level, high-traffic pavements Polymer modifiers are extremely common as binder modifiers because they enhance aggregate/binder bonding and other benefits. The tradeoff is a higher quality, typically about 40% over non-modified emulsions.
Polymer modifiers are taking the chip seal well beyond its classic application on low-volume roads. For example, polymer modification allows the use of emulsions in new, robust applications such as microsurfacing, ultrathin bonded wearing course,and macrosurfacing. One of the most versatile tools in the road maintenance arsenal, Microsurfacing is a polymer-modified cold-mix paving system that can remedy a broad range of problems on today's streets,highways, and airfields. Microsurfacing has added capabilities, thanks to the use of high-quality, carefully monitored materials, including advanced polymers and other modern additives. As usualJAITar's desire to move beyond the conventional products and constant endeavor to be the pioneers in the Industry had led to collaboration with flsamex(Europe} for manufacturing high quality Polymer Modified Bitumen Emulsions used for National Highways and Airport Runways.
Microsurfacing is applied in order to help preserve and protect the underlying pavement structure and provide a new driving surface. Roads chosen for microsurfacing application generally have low to moderate distress and narrow crack width.
Microsurfacing is typically applied on an intermittent, project-specific basis. Location, weather, traffic loading, and pavement conditions are factors used to determine if a microsurfacing application is appropriate. Roadways selected for microsurfacing treatment are commonly those which have slight to moderate distress, no rutting, and generally narrow crack widths, and in which a microsurfacing treatment would help extend the pavement life until resurfacing becomes necessary. Roadways chosen for cyclical microsurfacing applications would typically be treated every five to seven years.
Microsurfacing is commonly mixed in, and applied using, a purposely built truck, generally referred to as a "slurry truck." If the roadway segments to be microsurfaced are long and don't contain sharp curves, a "continuous machine" is sometimes used. This machine is capable of constant or continuous mixing and application of microsurfacing due to its large storage compartments and capability to attach to aggregate delivery trucks and tankers containing microsurfacing emulsion. This continuous operation provides the benefit of having few if any seams in the roadway which occur when operation stops.
Slurry trucks and continuous machines contain various compartments which hold the aggregate (fine crushed rock), water, polymer modified emulsion, and other additives, which are mixed in the on-board mixer. The microsurfacing mixture flows out of the rear and onto the pavement within the confines of a rear-mounted box referred to as a "micro box." This box contains an auger which turns to uniformly distribute the mixture across the width. Workers with squeegees follow behind and assist in spreading the mixture, correcting areas not properly covered, and keeping the mixture off of concrete improvements such as gutters.
A piece of burlap is often dragged behind with the goal of producing a smooth texture while applying the microsurfacing material. The texture of microsurfacing is different than that of asphalt pavement. The texture may have faint lines and be somewhat coarse. In addition, when the microsurfacing is first placed the surface is tender and can be marked up by sudden turning movements. These impressions on the pavement are temporary as seasonal weather and traffic smooth out these imperfections over time.
Once placed microsurfacing needs 1 to 2 hours to set or harden before the road is open for traffic.
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