15 March 2001
4.5.1. Breakup and cleanout method. This is normally accomplished using a pavement breaker
with removal by a backhoe (Figure 4.7.). This method usually disturbs the base and requires
replacement or filling with concrete.
It also has the potential to damage the adjacent slab if proper sawing procedures are not
followed. After the repair is isolated by full-depth saw cuts, additional saw cuts using a wheel saw
with at least 1 1/2 inch (38 millimeters) kerf, are made within the repair area, parallel and
approximately 1 1/2 feet (450 millimeters) from each perimenter saw cut or joint (Figure 4.8.).
Breakup should begin in the center of the removal area within the inner saw cuts. After breakup
of the inner area, a backhoe can then be used to gently pull the outer region free of the adjacent
slab, or this strip can be broken up with light hand-held jackhammers.
4.5.2. Lift-out method. This is normally accomplished using a crane or front end loader to lift the
deteriorated concrete from its position (Figure 4.9.). Lift-out operations should be closely
controlled to prevent accidents. This method generally does not disturb the base or damage the
adjacent slab. After the repair area is isolated by full-depth saw cuts, holes are drilled through the
slab and fitted with lift pins, and the slab is then lifted in one or more pieces. If it is necessary to
decrease the load, the slab may be cut into smaller pieces. During hot weather, the sawing
equipment may bind during initial transverse sawing procedures. It may be necessary to perform
sawing at night when the temperatures are lower and the slabs are contracting. Another solution
is to use a carbide-tipped wheel saw to provide a pressure relief cut within the patch area prior to
boundary sawing (Figure 4.10.). It is strongly recommended that the wheel saw cut be made no
closer than 6 to 8 inches (150 to 200 millimeters) from the proposed patch boundary due to possible
damage and microcracking in adjacent concrete. The same procedures may be used for the
removal of continuously reinforced concrete. Concrete in the two reinforcing lap areas must be
carefully removed so as not to damage the reinforcing and to avoid spalling of the concrete at the
bottom of the joint.