TM 5-822-11/AFP 88-6, Chap. 7
material and sealing the joint. All debris on the
cracks is usually accomplished using handtools.
pavement surface should be removed using a
Mechanical devices often do not adequately re-
vacuum sweeper.
move the sealant because the sealant becomes too
f. Applying Backer or Separating Material.
tacky when subjected to the action of mechanical
Once the joint has been thoroughly cleaned, the
bits.
backer or separating material is inserted to prevent
c. Routing or Sawing. Routing of the crack is
three-sided adhesion and provide the correct shape
accomplished using a vertical spindle router simi-
factor. In the old joint, the backer or separating
lar to the one shown in figure 4-6. The router
material also prevents compatibility problems
produces a reservoir for the sealant. An option to
between the new sealant and any old sealant that
using the router is to use a concrete saw. If the
remains in the bottom of the joint.
crack is straight enough, a standard self-propelled
concrete saw may be used to cut a series of
4-4.
Preparing Cracks in PCC.
intersecting straight lines that roughly follow the
a. Procedures for Preparing Cracks. Cracks,
crack. For more meandering cracks, a 6-inch
unlike joints, are irregular in dimension and direc-
diameter blade can be used to enable the crack to
tion, making them more difficult to prepare and
be followed. The sealant reservoir dimensions of
seal. Because of the irregular nature, the equip-
the crack should be similar to those of a normal
ment used to prepare joints may not be suitable to
joint and should be specified in the plans.
prepare cracks. The techniques change; however,
d. Crack Repair. The variable width and amount
the procedures remain virtually the same. The
of spalling typically found on cracks necessitates
procedures include sealant removal (from previ-
different procedures for different classifications of
ously sealed cracks), routing, crack repair, and
cracks. TM 5-624/AFR 85-8 provides the
cleaning.
procedures to follow for spall repair. General rec-
b. Sealant Removal. Sealant removal from
ommended procedures are as follows:
4-8
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