Annotated Literature Review for NCHRP Report 640 (2009)

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218 1.54.7 Performance No information is provided on the field performance of friction course. 1.54.8 Structural Design No information is provided on structural design of friction course. 1.54.9 Limitations No information is provided on limitations of use. 1.55 Pucher, E., J. Litzka, J. Haberl, and J. Girard. “Silvia Project Report: Report on Recycling of Porous Asphalt in Comparison with Dense Asphalt.” SILVIA-036-01-WP3-260204. Sustainable Road Surfaces for Traffic Noise Control. European Commission. February 2004. 1.55.1 General This report provides an overview for two separate issues: cleaning/maintenance of porous asphalt and the aspects associated with recycling porous asphalt. The report is a synthesis of practices found in the literature by the authors. 1.55.2 Materials and Mix Design No specifics on materials and mix design were given. 1.55.3 Benefits No specifics benefits were given. 1.55.4 Construction Practices No specifics construction practices were given. 1.55.5 Maintenance Practices The report provides information on three aspects of maintenance: structural maintenance, cleaning (unclogging) and winter maintenance. The authors indicate that raveling is the most common mode of distress for porous asphalt layers. Neither rutting nor cracking (except for reflective cracking) have been perceived as a major problem for porous asphalt. A joint Dutch and Belgian study cited by the authors indicate that typical structural maintenance methods conducted on porous asphalt include fog seal sprays, in- place recycling, overlays and cold-laid porous asphalt for local repairs (including potholes). Minor repairs can be made with dense-graded HMA as long as the size of the repair is not more than 10 percent of the surface area. A 1990 study referenced by the authors discussed the use of a suction sweeper with water jets for cleaning/unclogging porous asphalt pavements. However, in 1993 a PIARC report stated that cleaning porous asphalt with either high-pressure water or the vacuum sweeping machines have not been encouraging. Improvements in drainage capacity with these two methods were limited to the top portion of the layer and were only temporary. Studies from Austria indicated that cleaning should be started early in the life of a porous