What is Concrete Patching?

Concrete Patching and Partial-Depth Repair

Concrete patching is a repair that removes a damaged area of a concrete pavement slab and replaces it with new material. In the PAVER manual, a patch is an area where a filler material replaced the original pavement.

Two kinds of repair

A partial-depth repair replaces the damaged concrete in the upper part of the slab. AC 150/5380-6C uses it for a joint spall. A joint spall is a breakdown of the slab edge within 2 feet (0.6 m) of a joint. It usually does not go through the slab.

A full-depth repair removes the damaged concrete through the whole slab thickness. The base may also need repair after removal damage or water damage. AC 150/5380-6C gives three full-depth repairs: a corner break, a partial slab replacement and a full slab replacement. A corner break is a crack that goes vertically through the whole slab. Table 6-2 says to seal and maintain a corner break until it gets a full-depth patch.

How a patch is made

The AC 150/5380-6C procedure for a joint spall repair has these steps:

1. Mark the limits of the spall.
2. Cut vertical saw lines at least 2 inches (5 cm) deep and about 3 inches (8 cm) beyond the spall.
3. Remove the damaged concrete with hand tools or hammers under 30 pounds (14 kg).
4. Remove loose material and clean the area with high-pressure water.
5. Keep the joint open with a board, so the patch does not bond to the next slab.
6. Treat the surface as the material maker says. This can be neat cement grout or a liquid bonding agent.
7. Place the patch, finish it to match the texture of the pavement next to it, and cure it.
8. Seal the joint and clean the area before aircraft use it.

The AC says the minimum repair depth in concrete is 2 inches (5 cm). Thinner repairs usually deteriorate quickly on an airfield pavement and may benefit from epoxy materials.

For a full-depth repair of a corner break, the AC calls for a full-depth saw cut at least 2 feet (0.6 m) beyond the break. Where the crew removed cut dowels, it drills and epoxies new dowel bars. The AC says to place concrete only when the air is at least 4 degrees C (40 degrees F) and rising. The concrete must be at least 10 degrees C (50 degrees F).

Materials

AC 150/5380-6C says that Item P-501 concrete from AC 150/5370-10, or an equivalent state specification, may be used for repair. It also says that epoxy resins and special mixes may be used, as the maker requires. P-501 sets a maximum water to cementitious ratio of 0.45 unless a lower ratio is needed. It does not allow calcium chloride in the concrete.

Patches in a pavement survey

A PCI survey follows ASTM D5340 (AC 150/5380-7B). The PAVER manual for concrete airfields records a patch as a distress. A small patch is under 5.5 ft2 (0.5 m2). A large patch is over 5.5 ft2 (0.5 m2). A utility cut is a patch that replaced pavement for an underground utility. The severity levels are:

• Low. The patch works well with little or no deterioration.
• Medium. The patch has deteriorated or has moderate spalling at the edges. Patch material can be dislodged with considerable effort. This is a minor risk of foreign object debris (FOD).
• High. The patch has spalling or cracking and needs replacement. For a large patch, this includes considerable roughness or a high FOD risk.

AC 150/5380-6C says that a patch usually deteriorates faster than the original pavement. A patch is therefore a part of the pavement to check on every survey.