TM 5-822-11/AFP 88-6, Chap. 7
with carbide tipped bits, chip and damage PCC
b. Initial inspection. After the initial sawing to
pavements.
control cracking of the concrete, the saw cuts
g. Handtools. Enough handtools should be on
should be inspected for spalling. Excessive
hand to allow for work to continue in areas where
spalling of new concrete should not be found in
mechanized equipment cannot be used during the
normal construction. Spalls that extend more than
preparation of the joint or crack. This equipment
1/4 inch horizontally from the sidewall of the
can be straight or hooked bars with chisel shaped
initial cut should be repaired, since normally they
ends. Extra care must be used to ensure the
would not be removed during the widening
concrete is not damaged.
operation. Void areas caused by honeycombing of
h. Power Brooms. A vacuum type power broom
the concrete must also be patched to provide a
should be present to keep the pavement surface
solid joint sidewall for the sealant to bond.
free from all debris. A typical unit is shown in
c. Sawing Reservoir. After the required curing
figure 4-9.
period, the initial saw cut for crack control must
be widened to the size joint specified in the project
4-2.
Preparing New Joints in PCC.
specifications using a self-propelled concrete saw.
a. Initial Sawing. New PCC slabs will have
The depth of the cut should be uniform, and the
joints sawed or formed while the concrete is green
width should not vary along the length of the
(after it has taken initial set) to control cracking.
joint. A freshly sawn joint is shown in figure 4-
Concrete that cracks before the initial sawing must
11.
not be sawed. Instead, the resulting crack must be
d. Cleaning. Following the sawing operation,
prepared and sealed. The initial cuts or dummy
the joint should be sandblasted to remove laitance,
joints must be prepared to function as a joint. This
curing compound, sawing dust, and other foreign
preparation begins after the curing period of the
debris from the joint sidewalls and from the
concrete has ended. Figure 4-10 provides the
pavement surface adjacent to the joint to a width
sawing sequence in new concrete.
of approximately 1 to 2 inches. A multiple pass
4-4
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