UFC 3-270-02
15 March 2001
7.1.5. Cracks to be overlayed. Cracks larger than 1/4 inch (6 millimeters) in pavements that are
to be overlaid can be prepared by cleaning with the sandblaster, HCA heat lance, or wire brushes
and then cleaning with compressed air. Some specifications do not require the sealing of cracks
in pavements that are to be overlaid; instead, the cracks are sealed when they reflect through the
overlay and therefore require only air cleaning. Large cracks should be prepared as described
above.
7.2. Crack Widening. Meandering cracks should be widened using a router; whereas, the
straighter cracks can be widened using a saw with a small-diameter blade. When a saw is used,
the crack should be cleaned with a high-pressure water stream or a sandblaster to remove debris
created by the saw. The recommended procedure is to use a router since water would not be
required. When resealing, it is important to remove all of the old sealant that is in the crack. After
the crack has been widened or the existing sealant has been removed, the crack should be
cleaned to prevent any debris from contaminating the crack.
7.3. Initial Crack Cleaning. Cleaning of the crack can be accomplished by using the
sandblasting equipment, the HCA heat lance, or wire brushes. Information relative to this
equipment is presented as follows:
7.3.1. Sandblasting equipment. When the sandblasting equipment is used, a technique that
enables both faces of the crack to be sandblasted should be established. A multiple-pass
technique should be used which consists of positioning the sandblaster nozzle approximately
1 inch (25 millimeters) above the pavement surface, sandblasting the entire length of one crack
face, then sandblasting the entire length of the opposite crack face. Approximately 1 inch
(25 millimeters) of the pavement surface on both sides of the crack should also be sandblasted to
remove debris. The cracks should not be overblasted. Overblasting can damage the pavement,
causing raveling and premature bond failure of the sealant.
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