Using Polymer Modified Asphalt Emulsions in Surface Treatments A ...

traffic areas, as are durable, polish-resistant aggregates. It is common to have
individual asphalt emulsion specifications for cationic (CRS-2P), anionic (RS-2P)
and high float anionic (HFRS-2P) PMEs. Local agency names for these
emulsions will vary throughout the country.
For climate considerations, it is recommended that strict windows for application
temperatures be specified, but this area also needs further investigation as there is
clear evidence that curing, shelling and bleeding of chip seals are associated with
climatic conditions occurring well after the time of application. Superpave PG-type
specifications for HMA are based on climatic temperature ranges, which may also be
useful for asphalt emulsion surface treatments, especially microsurfacing. Although the
concept of 6°C grade increments based upon LTPPBind climate maps is attractive to
practitioners, failure properties have not yet been defined and failure limits have not
been established. For this reason, the FLH report-only lab testing format will only be
useful if measured physical properties can be tied to actual performance on the
pavement. It will be important to have longer-term pavement management data and
frequent video tapes of pavement condition so that field performance can ultimately be
used to set specification limits on promising laboratory performance measures.
As discussed in the literature review, polymers are believed to be advantageous for use
on hiking or biking trails and parking lots because of resistance to permanent
deformation, raveling surface aggregate and damage caused in parking lots when front
wheels are turned with no concurrent forward motion. Polymer modified materials have
also been shown to retard cracking, particularly the block cracking typically seen in
older parking areas. Bikers prefer microsurfacing/slurry seals over rougher chip seals
for trails. Small-sized aggregates should be used, and loose chips avoided. Although
microsurfacing and slurry seals are not typically compacted for paving applications, they
are compacted on airport runways and taxiways to eliminate FOD damage caused by
raveling surface aggregate.
If loose aggregate is perceived to be a problem on trails, evaluate the use of small
rollers on slurry/microsurfacing applications. Also, polymerized seals generally cure
faster, meaning faster reopening for its intended use. However, there is not much data
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