15 March 2001
Recommended tack coat materials include the use of cutback grades RC-70, RC-250; or
emulsion grades RS-1, MS-1, SS-1, SS-1h, CSS-1, CSS-1h; or asphalt cement grades AC-2.5,
AC-5, AC-10, AR-1000, AR-2000, or AR-4000. The tack coat application rate is 0.05 to 0.10
gallons per square yard (0.23 to 0.45 liters per square meter). A handspray wand should be used
to apply the tack coat (Figure 3.7.). If a wand is not available, a stiff brush can be used. In order
to prevent bleeding, too much tack should not be applied to the patch areas. (Too little tack is
better than too much.)
3.3.5. Place the patch material. This is the same as for full-depth patch (Paragraph 3.2.6.).
3.3.6. Compact the patch area. This is the same as for full-depth patch (Paragraph 3.2.7.).
3.3.7. Seal the patch. This is the same as for full-depth patch (Paragraph 3.2.8.).
3.4. Problem Areas. The major problem in constructing a successful patch is compaction of
both the base and patch material. Thin lifts (less than 3 inches (75 millimeters)) for compaction
will work best for each material. Too much prime or tack coat is also a problem. If a spray wand
is used, a test on an adjacent area should be performed to ensure the correct amount of prime or
tack coat is being applied. If not, spray nozzles, settings, or operational procedures should be
changed to assure the correct amount of coatings.
(NOTE: If RC-70 or other cutbacks are used as a prime or tack coat, their use must comply with
local environmental regulations.)