15 March 2001
to spraying the tack material. Proper nozzles and settings on the distributor spray bar or
handwand should be checked. Nozzles should be checked to ensure they are not plugged and
nozzles should be adjusted to the proper angle and height. Areas for tack coating shall be clean
and dry. The use of RC-70 or other cutbacks as a tack coat must comply with local
4.7. Fog Seals and Rejuvenators. A fog seal is a spray application of a diluted asphalt or tar
emulsion. Fog seals are used on sound plant mixed surfaces to seal a weathered, oxidized
pavement or on a pavement containing numerous small cracks. Emulsions used for fog seals are
SS-1, SS-1h, CSS-1, or CSS-1h. Rejuvenators are commercially available products which are
used to restore oxidized pavement surfaces. They should not be used on pavements that exhibit
raveling (unless raveling is very minor) or that have cracking (unless cracking is a very minor
hairline). Rejuvenators can cause restored pavement surfaces to be slippery for up to a year;
therefore, extreme care should be taken in choosing areas and application rates. Since there are
numerous commercially available products, a list of rejuvenators will not be presented.
4.8. Procedural Steps (Fog Seals and Rejuvenators). The following steps should be
conducted for the application of fog seals and rejuvenators.
4.8.1. Prepare the surface. The surface shall be thoroughly cleaned prior to application. This is
discussed in Paragraphs 4.2.1. and 4.5.1. Other distresses should be repaired before
4.8.2. Determine proper application rate. The application rate will vary according to the quantity
of material the pavement absorbs. Therefore, field test sections should be sprayed with different
application rates to determine the best rate. The rate should be adjusted so that the treated
surface is not slick, unstable, and does not contain excess material after 12 to 24 hours curing.