Concrete is a sturdy building material, but sometimes it can develop an issue called “honeycomb.” Let’s delve into what honeycomb is, why it happens, and how to fix it.
Imagine you have a concrete structure, like a column or a beam, and it ends up with a rough, pitted surface or voids inside. This is what we call honeycomb. It occurs when the concrete isn’t packed properly, leaving gaps or holes between the concrete and the aggregates (check the image above). Interestingly, honeycomb resembles a honey bee nest.
Detecting honeycomb is relatively easy; it becomes apparent when you remove the formwork after construction. If left untreated, honeycomb can seriously compromise the strength of the structure or member.
Let’s explore the reasons behind the formation of honeycomb in concrete:
Concrete Workability : When the concrete isn’t easy to work with.
Stiff Concrete Mix : Using a mix that’s too stiff or has set before placing.
Improper Vibration : Failure to vibrate the concrete adequately in the formwork.
Over Reinforcement : Using too much reinforcing steel.
Large Aggregates : Using excessively large aggregates.
Formwork Issues : Inadequate rigidity and waterproofing of formwork.
Excessive Pouring Height : Pouring concrete from a height beyond recommendations.
Steel Congestion : Steel congestion hindering the proper flow of concrete.
To prevent honeycomb, address the above issues during the construction process. Now, let’s discuss how to repair honeycomb if it has already formed.
Follow these steps to repair honeycomb in concrete:
Remove Loose Particles : Use a wire brush and chipping hammer to clear away loosened aggregates and concrete particles.
Thorough Cleaning : Brush and wash the affected surface to remove finer particles.
Surface Drying : Allow the surface to dry completely.
Apply Chemi-fix Glue : Apply Chemi-fix glue to the affected area.
Prepare Concrete Grout : Mix concrete grout with white cement and the recommended amount of water.
Fill the Area : Pour or paste the mixture into the affected area, ensuring it fills completely. For large honeycomb, create a pocket before pouring.
Formwork Removal : Remove the formwork after 12 hours.
Curing : Ensure proper curing of the repaired area.
By understanding and addressing the causes of honeycomb, as well as following these repair steps, we can maintain the integrity of concrete structures.
