Honeycombing in Construction
It is a type of defect in the RCC structure. In that place, coarse aggregate is visible very clearly. It is called a honeycombed surface. This specific place looks like a honey bees nest.
If the honeycombed surface is not treated then the RCC structure will not work properly as per the design. The honeycombed area allows things that are harmful to concrete-like water and air. The water and air affect the durability and permanence of the structure.
The reasons behind Honeycombing
a. The cohesion process of the concrete mix will not work.
b. The sustainability of concrete does not meet the appropriate requirement.
c. The connection to concrete is insufficient.
d. Steel blockage does not allow the concrete to flow to all corners.
e. Concrete will already set before placing it.
f. Formwork is inflexible.
g. A high free fall of concrete will happen while pouring.
Prevention of Honeycombing
1. The conhension process of all concrete batches should be reviewed.
2. The workability of concrete should meet the placement requirement. A lightly reinforced column can have a 75mm slump, a heavily reinforced column may require a 150mm slump.
3. Users should be sure about the proper compaction of placed concrete, vibrators to be removed as big air bubbles cease to come out. As per RCC sections. different sizes (25mm, 40mm, and 60mm) of the vibrator needle should be used.
4. Concrete should be compacted and worked perfectly around the reinforcement. Users should take care during the vibration, it may result in honeycombing, 5 % Voids in Concrete, 30% strength of concrete reduces.
5. It should be Cover with formwork, Pins, and spaces bars to layers of reinforcement for facilitating the proper compaction.
6. Steel Couplers also reduce steel blockage.
7. Concrete should keep the slump before it is placed. Concrete should be designed for retaining the slump till the time it is placed.
7. Concrete fall should be kept minimum. Concrete buckets with canvas pipes should be used for reducing concrete free fall height.
8. The formwork needs should be watertight.
9. Detailing and fixing of steel should be done to ease the concrete across all the corners and depths. If the steel blockage can’t be avoided then special concrete formulations are needed like self-compacting concrete, concrete with a lower maximum aggregate size (12.5mm), etc.
Procedure to Repair Honeycombed Concrete Surface
a. At first, users have to remove the loose part of concrete. It is removed by a chipper and hammer and/or wire brush. Users should not apply force like a breaker, electrical chipper or it would damage the good virgin concrete in the periphery.
b. After that users have to fix the packer in the affected area. Users should use the mechanical Injection pressure pump. They also have to grout the surface with non-shrink epoxy grout for filling the microvoids where the repair mortar cannot reach.
c. Users should apply the Post grouting to self-cure the repair mortar of equivalent compressive strength. Users must remember the fact that the buildup must not be more than 15mm thick.
In this article we discussed what is honeycombing in construction, the reasons behind honeycombing, the Prevention of honeycombing, and the Procedure to Repair Honeycombed Concrete Surfaces.
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