UFC 3-270-01
15 March 2001
48 hours. If a prime coat is not used, a thin tack coat should be applied to the edges and bottom
of the patch. This coating provides a good bond between the old and new materials. The patch
area edges shall be clean, dry, and free of any dust to ensure that the tack coat will bond to the
edges. 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.)
3.2.6. Place the patch material. A good-quality, hot-asphalt plant mix material should be used to
fill the patch. The material should be placed and compacted in 2- to 3-inch (50- to 75-millimeter)
lifts. In order for the patch to be level with the surrounding pavement, the patch area should be
overfilled to allow for compaction (Figure 3.8.). (A good rule of thumb for overfilling is about
40 percent -- depending on the mix; i.e., 3 inches (50 millimeters) compacted = 4 1/4 inches
(106 millimeters) uncompacted.) Patch material should not be overworked with a lute, shovel, or
rake. Overworking, especially at the surface, causes segregation of the mix.
3.2.7. Compact the patch area. Using an appropriate method, the mix shall be compacted to the
proper level. The size of the patch will determine which type compactor to use. For a very small
patch area or areas, a hand tamper can be used. Larger areas require the use of a vibratory
plate tamper or a steel-wheel roller (Figures 3.9. and 3.10.). To ensure the required compaction,
the proper equipment should be used and determined by the size of the patch. The edges of the
patch should always be compacted first, followed by compacting the remaining patch area in the
direction of traffic. Previous compaction lanes should be overlapped by about 6 inches
(150 millimeters) across the patch area (Figure 3.11.). When the patch is competely compacted,
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