TM 5-822-7/AFM 88-6, Chap. 8
the joint groove or by an aggregate interlock and
pavers are used, dowels shall be placed by bonding
dowels. Where dowels are required across transverse
the dowels into holes drilled into the hardened
contraction joints, suitable dowel-supporting
concrete with rotary core-type drills that can be
maintained in a position parallel to the surface of the
assemblies will be used and care taken to assure proper
alinement of dowels in the completed pavement.
pavement and perpendicular to the face of the edge
Requirements for dowel supports have been discussed
of the slab in a longitudinal direction. Some low impact
in c above. Where tie bars are required in longitudinal
energy hydraulic and electro-pneumatic drills have
contraction joints, suitable supporting devices will
been used to successfully drill dowel holes without
be provided for holding tie bars in place during paving
spalling the concrete. These and similar types of
operations, or the bars may be installed in front of
drills can be allowed if the contractor is able to
the paver by insertion into the unconsolidated,
satisfactorily drill the specified holes without undue
freshly placed concrete. The device for inserting the
spalling around the hole. The diameter of the hole
bars shall be mounted on the paver and will auto-
should be larger than the diameter of the dowel bar
matically insert the bars to the specified depth and
but should not be more than 1/8 inch larger than the
at the required spacing.
diameter of the dowel bar. The contractor will be
(2.) Joint types. Contraction joints may be
required to demonstrate to the contracting officer
constructed by sawing a groove in hardened concrete
that the dowels can be securely bonded and proper
or installing a suitable insert in freshly placed
alinement can be attained. Continuous inspection
concrete. Inserts will not be used on airfield
will be required thereafter to insure that the dowels
pavements without the prior approval of AFESC.
are securely bonded and that they are alined properly
Sawing of joints eliminates manipulation of freshly
both horizontally and vertically. The method used for
inserting the epoxy-resin grout into the hole shall
placed concrete after placement and provides the
best conditions for obtaining a smooth surface at the
place sufficient grout to completely anchor the dowel.
joint. However, sawing time is critical, and cracking
(2.) Transverse construction joints. When concrete
will occur at the wrong place if the joints are not
placement is stopped or interrupted for 30 minutes
sawed at the proper time. The filler-type joint forms
or longer, these joints are installed across the pave-
a weakened plane in the freshly placed concrete,
ment lane. Insofar as practicable, these joints will be
which induces fracturing of concrete at the joint,
installed at the location of a planned joint.
permits continuous curing of pavement, and provides
c. Expansion joints. When expansion joints are
protection for the joint until removed or depressed in
required within a pavement, joint assemblies
preparation for the sealing of joints. Although sawed
supporting both joint filler and dowels will be
installed before placing concrete. Accurate location
joints have been used successfully on many projects,
excessive cracking has occurred in some instances.
and alinement of joint filler and dowels are necessary
for proper functioning of joints. Since checking of
This is usually due to delayed sawing. When sawing
embedded items in joints installed within a paving
cannot be accomplished without undue uncontrolled
lane is extremely difficult, it is essential that
cracking due to unusual conditions, provisions shall
be made for using inserts. Filler-type joints maybe
assemblies used for supporting embedded items be
rigidly constructed and capable of resisting all move-
approved for longitudinal contraction joints when it
is demonstrated that these joints can be properly
ment and distortion during paving operations. Great
installed with vibratory equipment. The filler must
care and continuous inspection are required during
placing and finishing of concrete near joints to avoid
be maintained in a vertical position and in proper
displacement of joint filler and dowels. Additional
alinement in the finished pavement.
hand vibration will be required around the joint
(3.) Installation of insert-type joints. Insert-
type joints will be installed immediately after all
assemblies to insure adequate consolidation. The
machine finishing operations are completed. The
contractor is required to provide a template for
macine for installing the insert shall have a vibratory
checking the position of the dowels.
bar that cuts a groove in concrete and simultaneously
d. Contraction joints.
(l.) General. Contraction joints use a groove to
installed an insert in required locations. The intensity
form a weakened plane in the concrete, as the concrete
of vibration on the bar will be variable as necessary
to form the groove in the freshly mixed concrete and
undergoes shrinkage, a fracture forms through the
concrete below the groove. Load transfer is provided
to consolidate the concrete around the insert after it
is in place. Inserts must be the proper depth for the
by aggregate interlock in the fracture plane below
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