Honeycomb In Concrete:
Honeycomb is the rough pitted surface or voids in concrete formed due to improper compaction or incomplete filling of the concrete.
In this formation, concrete not filled properly and create gaps/voids in between concrete and aggregates ( As shown in the above image). Honeycomb is mostly seen in columns and beams and can easily be detected just after removing the formwork. Actually, it looks like a honey bee nest.
Honeycomb is a serious problem of concrete which should be treated carefully. Otherwise, the structure or member may lose its strength.
The various reasons for honeycomb in concrete are as following:
1. Inappropriate workability of concrete.
2. Use of stiff concrete mix or the concrete is already set before placing.
3. Improper vibration of concrete in formwork.
4. Over reinforcement.
5. Use of larger size aggregates in excessive amount.
6. Formwork is not rigid and watertight.
7. Concrete is poured from more than allowable height.
8. Congestion of steel is preventing the concrete to flow over all corners.
So if we overcome the above reasons, we can easily prevent honeycomb in concrete. Here I will discuss further how to repair honeycomb if it is already formed in the concrete.
Repairing Of Honeycombs In Concrete:
1. First, remove the loosened aggregates and concrete particles from the affected surface by using a wire brush and a chipping hammer.
2. Clean the surface thoroughly with a brush to remove finer particles and then wash the surface with water.
3. Let the surface to dry well and apply Chemi-fix glue on the area.
4. Now mix the concrete grout with white cement and add required amount of water ( as per the specification recommended by the manufacturer).
5. Then pour/paste the mixture in the affected area to fill it completely. In case of large honeycomb, the concrete mixture should be poured after creating a pocket.
6. Remove the formwork after 12 hours and then cure it well.