CONVENTIONAL REPAIR OF SPALLED CONCRETE

Repairing spalled concrete using conventional methods involves several critical steps to ensure the durability and effectiveness of the repair. Spalling occurs when the concrete surface flakes, cracks, or breaks off due to environmental stress, improper installation, or reinforcement corrosion. Here’s a step-by-step guide:

1. Assess the Damage

• Identify the Cause: Spalling can result from freeze-thaw cycles, corrosion of embedded steel reinforcement, poor concrete mix, or construction defects.
• Measure the Extent: Determine the depth and area of spalling to decide on the scope of repair.

2. Prepare the Area

• Mark the Repair Zone: Use chalk or spray paint to delineate the damaged area.
• Remove Damaged Material:
• Use a chipping hammer, jackhammer, or hand tools to remove loose, weak, or deteriorated concrete.
• Expose the reinforcement steel if corrosion is present.
• Clean the Surface:
• Remove debris using compressed air, a vacuum, or a power washer.
• Ensure the surface is free of dust, oil, grease, or contaminants.

3. Treat the Reinforcement Steel

• Inspect for Corrosion: Remove rust from exposed rebar using a wire brush, sandblasting, or a rust remover.
• Apply a Corrosion Inhibitor or Primer: Coat the cleaned steel with an anti-corrosion compound to prevent further deterioration.

4. Apply Bonding Agent

• Prepare the Surface: Dampen the concrete to prevent it from absorbing moisture from the repair material.
• Apply Bonding Agent: Use a concrete bonding adhesive to ensure proper adhesion between the old and new concrete.

5. Mix and Apply Repair Mortar

• Choose the Right Material: Use a polymer-modified repair mortar, non-shrink grout, or other pre-packaged repair products designed for spalled concrete.
• Apply the Mortar:
• Pack the repair material into the spalled area using a trowel or putty knife.
• Smooth and level the surface to match the surrounding concrete.
• Ensure proper consolidation to eliminate air voids.

6. Cure the Repair

• Moist Cure: Cover the repaired area with wet burlap or plastic sheeting to retain moisture.
• Apply Curing Compound: Use a curing agent to prevent rapid drying and cracking.
• Allow Time for Curing: Follow the manufacturer’s instructions for the repair material to achieve full strength.

7. Seal the Surface

• Protect the Repair: Apply a concrete sealer to enhance durability and protect against water infiltration, freeze-thaw cycles, and chloride attack.

8. Inspect and Maintain

• Conduct a Final Inspection: Check for proper adhesion, smoothness, and blending with the surrounding concrete.
• Regular Maintenance: Clean and seal the surface periodically to extend the life of the repair.