Section 2426. Structural Concrete Repair
A. Repair spalled or deteriorated structural concrete as specified in the contract documents. This work may include the installation of concrete anchors, reinforcing bars, or wire mesh.
1. General.
Repairs shall be placed against sound concrete.
2. Shallow Repair.
Repair that:
· Is 3/4 inch to 1 1/2 inch (20 mm to 40 mm) in depth, and
· Does not use forms to support the patching material, except
· where the patching material cannot support itself.
3. Regular Repair.
Repair that:
· Is a minimum depth of 1 1/2 inch (40 mm), or 3/4 inch (20 mm) behind an unbonded reinforcing bar, and
· Uses forms.
B. The Engineer will outline the areas to be repaired.
A. Use materials meeting the appropriate requirements of Division 41.
1. Shallow Repair.
Use approved material from Materials I.M. 491.08 in accordance with manufacturer’s recommendations.
2. Regular Repair.
Furnish Class O concrete. Use 3 inches (75 mm) as the target slump, with a variation not to exceed ± 1 inch (25 mm). For placements requiring higher slump, a mid range water reducer may be used with a target slump of 5 inches (125 mm) or a high range water reducer may be used with a target slump of 7 inches (175 mm).
Use equipment that meets the requirements of Article 2413.03, A, 2, to prepare the repair area.
1. Remove all loose, disintegrated, and unsound concrete from the repair areas. Outline all repairs with a 3/4 inch (20 mm) deep saw cut. Concrete anchors and wire mesh may be required, as shown in the contract documents. Overhead repairs may require special procedures, as proposed by the Contractor and approved by the Engineer.
2. After removal of loose, unsound concrete, sandblast the repair area and follow with an air blast with oil free air so the substratum is sound, clean and free of all contaminants. Exercise extreme care in concrete removal so that prestressed strands are not damaged. The substrate must be dry prior to concrete placement or bonding grout application, if required.
3. Sandblast exposed reinforcement to remove all rust. Remove and replace damaged or badly corroded reinforcing bars, as directed by the Engineer.
1. Shallow Repair.
a. Bonding Grout.
Apply
bonding grout to the properly cleaned, dry surface of the old concrete with a
stiff bristle brush. Do not prewet the concrete surface before placing grout. Prepare concrete surface
in accordance with manufacturer’s recommendations.
b. Repair Concrete.
Place and compact repair
concrete. before the grout dries. If the grout dries prior to concrete placement,
remove the grout by sandblasting and reapply. Strike off and finish
the repair concrete to the correct lines.
2. Regular Repair.
a. Place concrete according to Article 2403.03, C.
b. When repairing a vertical face, place the patch in heights not to exceed 4 feet (1.2 m). Provide access ports at 4 foot (1.2 m) intervals in the forms for placement and vibration. Remove forms according to Article 2403.03, M.
For
Class O concrete, Aapply white
pigmented curing compound to the concrete immediately following concrete
finishing or immediately after removing forms, if used. Apply curing compound
according to Article 2403.03, E, except use an application rate of 100 square
feet per gallon (2.5 m2/L). Use manufacturer’s recommendations for curing products from
Materials I.M. 491.08.
2426.04 method of measurement.
The Engineer will determine the square feet (square meters) of Concrete Repair by measuring the surface dimensions of the area repaired to the nearest 0.1 foot (0.1 m). Distinction will not be made between shallow repair and regular repair.
A. Payment for the number of square feet (square meters) of Concrete Repair completed, measured as provided above, will be the contract unit price per square foot (square meter).
B. Payment is full compensation for:
· Removal of excess concrete from the project,
· Furnishing all materials and equipment, including concrete anchors, wire mesh, and reinforcing bars, if required.
· Sandblasting exposed reinforcement,
· Removing and replacing damaged reinforcing bars,
· Forms, and
· Labor necessary to complete the work according to the contract documents.