15 March 2001
produce a sharp metallic ring. The repair boundaries should be extended beyond the detected
delaminated or spalled area by 3 inches (76 millimeters) to assure removal of all unsound
concrete (Figure 5.3.). The repair boundaries should be kept square or rectangular in line with
the jointing pattern to avoid irregular shapes. Irregular shapes may cause cracks to develop in
the repair material. If repair areas are closer than 24 inches (600 millimeters) apart, they should
be combined. This will help reduce costs and eliminate numerous small patches. The actual
construction of the concrete repair should comply with AFM 85-8.
5.4. Removal of Existing Concrete. Removal of existing concrete can be accomplished by
sawing and chipping or by a milling process. To remove concrete by sawing and chipping, a
minimum 2-inch- (50-millimeter-) deep saw cut should be made (in a rectangular pattern at least
3 inches (150 millimeters) outside all visible deterioration) around the perimeter of the repair area.
This will provide a vertical face of sufficient depth to give integrity to the patch (Figure 5.4.).
Additional sawcuts may be made within the repair area to speed chipping. A saw cut 2 inches
(50 millimeters) away from joints might reduce the possibility of damaging the opposite joint face.
A saw cut along the opposite joint face made by skimming the blade along the joint face will
remove sealant residue and leave a clean vertical joint face (Figure 5.5.). Concrete within the
repair area should be removed to the bottom of the saw cuts or to 1/2 inch (13 millimeters) into
visually sound and clean concrete, whichever os deeper, with light pneumatic tools. It is
important that the proper tools are used. The recommended maximum size of the chipping
hammer for partial-depth repairs is 30 pounds (13.6 kilograms). Concrete within the repair area
can also be removed by carbide-tipped cold milling equipment. Cold milling is especially effective
where the repair area extends over the majority of the slab width. Milling machines must be
equipped with a device for stopping at a preset depth to prevent excessive removal or damage to
existing dowel bars or reinforcement. After removal of the concrete in the repair area, the
pavement should be sounded again to ensure all unsound or delaminated concrete has been