TM 5-822-11/AFP 88-6, Chap. 7
than the width of the joint being cleaned. The use
the sealing project begins. Sandblasting equipment
of V-shaped plows should never be allowed. The
is shown in figure 4-4. The nozzle should have an
V-shaped plow can chip the pavement damaging
adjustable guide that holds the nozzle approxi-
the joint face. Several sizes of tools should be on
mately 1 inch above the pavement aligned directly
the jobsite to match changes in joint sizes. Thin
at one of the joint or crack faces. The height,
cutting tools may be used if a multiple pass
angle of inclination, and size of the nozzle must be
technique is used and extreme care is taken by the
adjusted as necessary to obtain satisfactory results.
operator to prevent damage to the concrete pave-
A small section of angle iron may be attached to
ment. The tool should be mounted to allow for
the nozzle to aid in directing the blast at the joint
setting the proper depth control and provide both
or crack faces. Great care must be exercised if the
lateral and vertical movement of the tool. The
sandblast equipment is used for cracks in
allowable movement will help avoid spalling of
bituminous pavements because overblasting can
the concrete around the joint. The joint plow is
easily occur. Overblasting can damage bituminous
usually outfitted with a spring or hydraulic
pavement causing raveling and premature bond
mechanism that releases pressure on the tool
failure of the sealant.
before spalling of the concrete occurs.
c. Sandblasting Equipment. The sandblasting
with the sandblasting equipment, and it airblows
equipment must include an air compressor, hose,
loose debris from the joints or cracks. For sand-
and long wearing 0.25-inch verturi type nozzle of
blasting, the compressor should furnish approxi-
the proper shape and size for the joints and/or
mately 150 cubic feet per minute while maintain-
cracks in the pavement. The use of sandblasting
ing a line pressure of approximately 90 psi at the
equipment must comply with occupational and
nozzle during actual use. The compressor must
health standards, and protective clothing must be
have in-line traps that will maintain the air free of
worn by the operator at all times. The standards
water and oil. Both moisture and oil interfere with
must be thoroughly discussed and reviewed before
the sealant bonding to the joint or crack face.
4-2
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