15 March 2001
4.3.4. Saw cuts shall be straight lines forming rectangles in line with the jointing pattern.
4.4. Sawing of Repair Boundaries. The repair boundaries of mesh reinforced, plain doweled, and
plain jointed concrete pavement are typically provided by diamond blade sawing (Fig- ure 4.5.).
Sawing is the recommended method. Air hammers should not be used to outline the area. The
rough joint formed by air hammers typically spalls in service. It's difficult to lift out the concrete
within the repair boundaries or break it up with large pavement breakers. The partial- depth saw
cut does provide some aggregate interlock due to a rough face, but microcracking will develop at
the bottom of the repair area and the bottom of the slab may spall when using a large pavement
breaker to shatter the concrete within the repair boundaries. If this occurs, the saw cut must be
made deeper, the size of the pavement breaker should be limited, and the pavement breaker
should not be used in the immediate joint area. Normally, pavement breakers should be hand-
held and not weigh over 30 pounds, (14 kilograms). The full-depth saw cuts will completely sepa-
rate the concrete that is to be removed, leaving verrtical faces, and eliminate unwanted damage
at the bottom of the slab; however, it will not provide adequate aggregate interlock for the patch.
The repair boundaries of continuously reinforced concrete pavement are provided by sawing full
depth at the repair boundaries. Partial-depth saw cuts above the reinforcing steel are then
provided at a distance required by the lap length of the reinforcement (TM 5-825-3/AFM 88-6,
Chap. 3) from the repair boundaries (Figure 4.6.). The partial-depth saw cuts should be located
at least 18 inches (450 millimeters) from the nearest tight crack and should not cross an existing
crack. Should any of the reinforcing steel be cut while sawing, the repair area must be increased
by the required lap length of the reinforcement.
4.5. Removal of Existing Concrete. Procedures used for removal must not spall or crack
adjacent concrete or significantly disturb the base or subgrade. There are two basic methods to
remove concrete pavement: