UFC 3-270-02
15 March 2001
9.1.3. Large cracks (greater than 2 inches (50 millimeters)). Cracks that are 2 inches
(50 millimeters) and larger should be filled with a sand asphalt or fine-graded asphalt mix. The
procedures and equipment used are identical to those used to repair potholes. The cracks
should be squared by sawing, filled with asphalt mix, and compacted. To obtain a high-quality
patch, the edges should be vertical and the crack must be clean. The asphalt material could
prematurely fail if the proper cleaning and patching procedures are not followed. Additional
information on these procedures may be obtained from Departments of the Army, Navy, and Air
Force TM 5-624/NAVFAC MO-102/AFJMAN 32-1040.
9.1.4. Cracks in pavements that are to be overlaid. Small and medium cracks in pavements
that are to be overlaid can be filled with an emulsion, a sand emulsion mixture (Figure 9.1.), or
one of the types of sealants previously mentioned. The material should be recessed in the crack
a minimum of 1/4 inch (6 millimeters) to prevent the material from "bleeding" through the overlay.
Bleeding occurs when the asphalt cement in the crack sealant material is drawn to the surface of
the overlay. Bleeding causes the pavement above the crack to become soft, and a crack in the
overlay is usually the end result.
9.2. Backer Rod Material. The backer rod (Figure 9.2.) is a compressible, nonshrinking,
nonabsorptive material whose melting point should be higher than the pouring temperature of the
sealant. The backer rod should be approximately 25 percent wider in diameter than the nominal
width of the crack. The larger size will enable the sealant to be inserted without dislodging the
backer rod. The backer rod should be placed to a depth that will provide a shape factor (depth to
width ratio) of approximately 1. However, the maximum depth that the backer rod should be
placed is approximately 3/4 inch (19 millimeters). This will provide a reservoir for the sealant that
will maintain the internal stresses in the sealant at a minimum. High internal stresses can create
cohesion failure, a splitting of the material, or dislodge loose aggregate from the pavement,
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