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

seal stone retention, and to provide a more water-resistant, smoother riding surface.
Polymer modifiers in general have been shown to improve water resistance (69, 70).
However Solaimanian notes that microsurfacing cannot be used to correct an
underlying water problem present in an incorrectly constructed chip seal or deficient
base pavement. Indeed, in such cases the use of polymers in surface treatments can
actually exacerbate underlying deficiencies, by entrapping water which can lead to
stripping and freeze-thaw related damage (72).
2.6 Polymers and Traffic Volumes
The Context Sensitive Roadway Surfacing Selection Guide (2005) specifies roadway
volume classifications based upon ADT which are used in practice by the FLH Division
(73). Table 8 presents this classification system for reference.
Table 8: Federal Lands Traffic Volume Classification (73)
Design Volume
(vehicles/day)
Suggested
Descriptive Term
Preferred
Design Speed (mph)
Minimum
< 200 Very Low 40 30
200 -400 Low 50 40
400 – 1,000 Medium 50 40
1,000 – 4,000
55 45
4,000 – 8,000 High
60 50
> 8,000 60 50
A survey of chip seal best practices performed by Gransberg and James (2005) reveals
that many U.S. highway agencies restrict their use of chip seals to roadways with
maximum traffic volumes of < 2,000 ADT (68). The primary reason cited for confining
chip seal applications to lower volume roads, is the loss of stone which can result in
inordinately high levels of windshield damage. In this regard, it has been wellestablished
that when properly formulated, applied, and cured; polymer modifiers can
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