How to Repair Honeycomb in Concrete Structures?

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Honeycomb is a rough and stony concrete appearance with air spaces between aggregates. It may occur due to improper concrete workability and concrete pouring practice, excessive water in the concrete mix, inadequate formwork rigidity and waterproofing, etc.

It is found mostly in beam-column junctions, corners, inaccessible areas where proper compaction is not doable, and steel-congested areas. It also occurs in columns, walls, foundations, but is less likely in beams.

Honeycomb in concrete can cause severe problems if it is spread over a wide area, exposes the steel bars, and extends deep into the concrete (equal or greater than 5 cm). Hence, the affected areas should be repaired as soon as possible. Not only does it distort the appearance of the structural members, but it also reduces structural strength and durability.

How to Repair Honeycomb in Concrete Structures?

The repair process involves removing loose material, cleaning the affected area, applying suitable repair material, and then curing to gain adequate strength.

Generally, the procedure for the repair of honeycomb in concrete members such as columns and beams is as follows:

1. Remove loose concrete or loosened aggregate by hammer or wire brush. Prevent the application of large forces such as electrical chippers to avoid sound concrete damage around the honeycomb area.
2. Clean any dirt or loose material from the area.
3. Wet the cleaned area before applying the repair material.
4. Fill small voids and cracks using a mechanical injection pressure pump with a suitable material such as non-shrinkage epoxy grout.
5. If the honeycomb covers a large area, you may need to create a patch hole to ensure proper bonding.
6. Place formworks if necessary, and pour the grout.
7. If formwork is not used, apply suitable repair material such as non-shrinkage, high-strength grout.
8. The filling process should be in a 15 mm thickness layer if the depth of honeycombing is greater than 5 cm. It is recommended to wait for a while (30min) before applying the next layer.
9. Repair material strength should match the virgin concrete of the structural element.
10. Provide texture and color required to match the surrounding concrete and maintain aesthetics.
11. If present, remove formworks after 12 hours of repair based on the type of material used and ambient conditions. Cure repair material to gain adequate strength.

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Read More:

Honeycombs in Concrete – Their Causes and Remedies

How to Place, Compact, Cure, and Rectify Defects of Concrete? [PDF]

Injection Grouting: Purpose, Procedure, and Field Considerations