What is Honey comb in concrete & How we fix it

Honey combs can be simply be defined as hollow spaces and cavities left in concrete mass on surface or inside the concrete mass where concrete could not reach.

Honeycomb is a serious problem of concrete which should be treated carefully. Otherwise, the structure or member may lose its strength.

Honeycomb is seen in any concrete structure and can easily be detected just after removing the form-work. And it looks like a honey bee nest.

Reasons for honeycomb in concrete are Describe as following:

• Use of larger size aggregates in excessive amount.
• Less cover to reinforcement bars
• Improper vibration during concrete.
• Use of Segregate concrete.
• Form work is not leakage proof Slurry flow out from gaps
• Reinforcement is so con gusted
• Poor workman ship
• water Ratio is not according IS ( water cement ratio that should there is within the range of 0.4 to 0.6 ) or according temperature

Note :-

According my opinion wherever honeycombs are observer concrete should be broken and the portion should be re concreted after applying grouting chemical to the old surface. Because honey decrease the structural strength of the structure.It defect not only reduces the load bearing capacity but water finds an easy way to reinforcement rods and rusting and corrosion starts.

REPAIRING OF HONEYCOMBS IN CONCRETE:

1. Remove the loose aggregates and concrete particles from the affected surface by using a wire brush or chipping hammer ( 4 to 7 kg ) or with water blasting
2. Hack off all the loose concrete until sound and solid concrete is achieved .All the leftover concrete dust is then washed away with water or blown using compressed air. This is to ensure good bonding between the concrete and the repair material
3. Best option is to use Non-shrink grout Sikka Grout 215 or Flow grout 60 is then mixed it  
4. Add 4.2 litre water per bag 30 kg but here you need small amount of grout so add water according the quantity and mechanically for at least 3 minutes with a slow speed mixer or until a smooth, uniform consistency is achieved.
5. Using a masonry trowel, a layer of the non-shrink grout is then applied onto the surface of the affected area.
6. Level the surface to the required shape and finishing. The affected area shall be brushed / trowel smoothly.
7. The repaired area will be hardened after about 4 to 5 hours and cure it properly for 7 days