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Honeycombs in Concrete | Type, Cause, prevent and Remedies

What is Honeycombing in Concrete?

Honeycombing in concrete can be defined as a rough concrete surface area where paste doesn’t fill around aggregate or concrete containing voids or concrete which have hollow cavities

In other simple word concrete which not cover reinforcement properly due to concrete has not reached enough

Honeycomb Structure in Concrete maybe create by the insufficient amount of fine aggregate in the concrete mix also due to wrong aggregate grading  or bad concrete mixing of ingredient or poor vibrator used

Honeycomb detect in the surface if available as soon as we remove the shuttering but if honeycomb present inside of concrete then it required  advanced technic like ultrasonic testing


Why Honeycomb produce and their remedies
Why Honeycomb produce and their remedies

Types of honeycombing in concrete

There are many concrete honeycomb pattern but I try to describe in a simple way

Small size honeycomb

When the depth of honeycomb is less than 25 mm comes in small size honeycomb

Medium size honeycomb

When the depth of honeycomb is more than 25 mm is comes but not exposed reinforcement to the environment in Medium size honeycomb

Large size honeycomb

When the depth of honeycomb is more than 25 mm is coming and also exposed reinforcement to the environment in Large size honeycomb

Where the Honeycombs form?

In every part of building means where concrete defects honeycomb in part of building

Cause of Honeycomb in Concrete

1. Improper Workability

Improper workability of concrete which has stiff (not reach) to properly cast in formwork

Workability is a wider topic to explain in the honeycomb article so please read the already published article in deep if you want to understand in-depth about workability

2. Water Cement ratio

High W/c ratio

If water use making concrete in excess amount then water/cement ration goes high which be the reason of segregation in the concrete end of result honeycomb in concrete created

Low w/c ratio

If water use in concrete below the certain limit which determined during the mix design of concrete than concrete pore enough to reach every corner or badly cast in formwork end of result honeycomb created

Sometime admixture used to improve workability without the use of excess water

3. Higher A/C ratio

It also knows as Improper mixing of concrete ingredients like low cement contain or high amount aggregate which forms a poor mix design which is not good for poured and also not fully compacted so that it also is the cause of honeycomb

4. Improper Compaction of Concrete

If labour does not have technical skill knowledge about the use of vibrator during compaction then there is the possibility of failure of formwork by touch vibrator to formwork and also reinforcement so that cement slurry leak through from works and honeycombs comes

When we use an excess amount of vibrator during casting of concrete then it leads honeycombs to produce in concrete also lead segregation

5. Casting Concrete from a Height

When you cast concrete from a certain height then there is a high possibility of honeycombs in concrete due to segregation and lots of factors 

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Effect of honeycomb in concrete

  • Reduce load carrying capacity of concrete alternatively affect the strength of the structure
  • Increase in the permeability of concrete
  • The honeycombed surface may be cured by pressure grouting of cement slurry
  • Water and air enter the structure which leads to rusting and corrosion of reinforcement bars
  • Corrosion of reinforcement due to honeycombs reduce the structure of life/durability

How to prevent honeycombing in concrete?

There are various technic to for how to avoid honeycomb in concrete because every engineer has a unique idea to overcome in honeycombs 

List of an idea to prevent honeycombs of concrete

  1. Be careful during the calculation of mix design proportion
  2. Provide proper minimum cover as per structure element refer to this link
  3. At the time of casting use proper vibrator. Guide labour to use of vibrator so that chances of failure of formwork eliminated so cement slurry not leak from formwork or if leakage
  4. The casting of concrete must be cast from the desired height level means penetrated properly. This will help to reduce honeycomb concrete
  5. After casting of beam or columns the sides should be To slowly knock immediately by using a wooden hammer from outside which greatly helps to reduce honeycombs
  6. Supervising by expert important before casting because if reinforcement placement is wrong like to close due to improper lapping or at the junction, it is also the top reason for honeycombs
  7. Concrete should be cohesive enough which help greatly to avoid honeycombs also in the durability of the structure
  8. The slump of concrete maintain properly which help decrease the chances of honeycomb
  9. Be care full because contractors and supervisor generally try to hide their honeycombs problem by applied cement past on it which create serious issues

Remedies for honeycombing in concrete

How to Repair Honeycomb Concrete is the major goal of any contractor or supervisor

We can Cure for Honeycombs or repair Honeycombs in Concrete structure in the following ways

  • Strictly speaking, where honeycombs are found in concrete, the affected area should be demolished, and even the part should be reconstructed after applying grouting chemicals to the old surface

  • Corrosion is a process that continues even in good concrete through reinforcement rods. This is the result of losing the grip between the concrete and the reinforcement, which is very dangerous to the safety and life of the concrete structures so casting done in a better way if honeycomb has seen then compacted properly or cast again
  • Keep the height of casting should be minimum as possible
  • Honeycombs as a defect not only reduce the load-bearing capacity of concrete but also reduce the durability of structure so we can safe structure and improve durability by eliminated honeycomb
  • The sides should be To slowly knock immediately by using a wooden hammer from outside which greatly helps to reduce honeycombs
  • Properly Grading the Size of aggregate also at places of the junction of beam-column use 20 mm aggregate and used slightly more cement water to avoid honeycombs
  • Clean the area before applying repaired materials
  • By filling cracks and voids using a mechanical injection of concrete honeycomb repair material with help of pressure pump such as non-shrinkage epoxy grout
  • Materials should match the characteries with virgin concrete for repair honeycomb on concrete
  • You need to make a patching honeycomb concrete hole to make sure proper bonding If the honeycomb covers a large subject area
Concrete honeycomb repair methods are full describe above as all possible method

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