15 March 2001
2.2.2. Sprayed asphalt surface treatments. Surface treatments include prime coats, tack coats,
fog seals, and rejuvenators. A prime coat is applied to a nonbituminous base course during
construction and prior to placement of a bituminous pavement. A tack coat is applied to an old
pavement surface prior to the surface being overlaid with a new ACC pavement. Fog seals and
rejuvenators are repair alternatives used for repairing small cracks (less than 1/4 inch
(6 millimeters)) or pavements with weathered, oxidized, or brittle surfaces.
(NOTE: Due to possible foreign object damage (FOD) problems, the major command (MAJCOM)
or Transportation Systems Center (TSMCX) engineer must be consulted prior to using a surface
seal or rejuvenators as repair options.)
2.2.3. Sprayed asphalt with surface aggregate. Surface aggregate treatments consist of sprayed
asphalt applications followed by one or more layers of aggregate. The two types of treatments
are single bituminous surface treatment (SBST) and double bituminous surface treatment
(DBST). These two treatments are used to repair areas containing small cracks (1/4 inch (6
millimeters) or less), weathering/raveling, polished aggregate, block cracking, and low-severity
alligator cracking (usually a temporary repair). A variational treatment used to repair bleeding
consists of applying hot sand to the distress, followed by rolling.
2.2.4. Asphalt slurry seal. A slurry seal consists of a mixture of aggregate and asphalt emulsion.
Slurry seals are used to repair the same distresses as discussed in Paragraph 2.2.3. (sprayed
asphalt with surface aggregate).
2.2.5. Patching (filling ruts and depressions). A patch can be used to repair rutting and
depressions by filling the distresses with asphalt.
2.2.6. Porous friction surfaces. Special repair procedures specifically applicable to these porous
friction surfaces are presented and discussed in Chapter 8.