After 28 days of curing, when you remove the formwork from the column, you find out hollow spaces and cavities there. This thing is known as the concrete honeycombing issue. It looks like a honey bee nest and is a critical issue for any structure component.
There are several reasons behind occurring this issue, such as air bubbles, improper concrete mixing, improper water-cement ratio, segregation issue, and so on. If you are looking for brief details about honeycombing in concrete then you are at the very right place.
In today’s article, we have discussed what is honeycombing, why this issue occurs, types of honeycombing, problems you will face, and last but not least, remedies for this issue. Read on and learn everything about honeycombing issues in concrete. Let’s begin then!
What Does Honeycombing in Concrete Mean?
Having voids or gaps in the concrete structure is known as a honeycomb issue. When this issue shows up, it looks like bee nets and that’s why it was named honeycombing issue. It’s a very critical issue for concrete structures as it can provide a negative impact issue on the structures.
It will reduce the strength of the structure with time and if it is not cured properly then the structure will collapse. It basically happens when there are air voids between the course and the aggregate. There are other reasons and we will discuss it in the later part of this article.
Different Types of Honeycombs in Concrete
The types of honeycomb issues are classified according to the depth of them in the concrete. Based on their depth, honeycombs are found at 3 different depths or you can say, 3 types of honeycombs can be seen. They are –
- Large Sized Honeycomb – It has a depth of more than 100 mm.
- Medium-Sized Honeycomb – has a depth of 25 mm to 100 mm.
- Small Sized Honeycomb – has a depth of less than 25 mm.
Among these three, a large-sized honeycomb in the concrete is the most dangerous one as it exposed the rebar or steel to the environment.
Reasons Why Honeycomb Issue Shows in Concrete
As we have early stated that when there are gaps between coarse and fine aggregates, this issue occurs on the concrete. However, there are other several reasons too and we will discuss them here.
Honeycomb Shows up if There are Issues with Concrete Used in Casting
An issue with concrete is one of the main reasons behind honeycombing in concrete. There are several things in concrete, if the things are failed during construction then honeycomb issues happen in the concrete.
- If the concrete mix design isn’t homogenous mixing, then a honeycomb appears on the concrete.
- If stiff concrete is used. Stiff concrete reduces the workability of the concrete.
- Improper water-cement ratio in the mix design.
- Used concrete that was set earlier before placing it inside the formwork.
- Improper coarse aggregate grading.
If there are Issues During Concrete Casting
Honeycomb also forms if there are issues during concrete casting. Here are the reasons –
- Pouring concrete from more than 1.5 m whereas it is prohibited to pour concrete from more than 1.5m.
- Provide excessive vibration for concrete compaction which leads to segregation issues.
If there are issues with Formwork
- Moving formwork before setting concrete.
- Didn’t use waterproof formwork.
- Having gaps at the formwork joints that causes bleeding of concrete.
- Failed to manage clear cover of reinforcement during setting formwork.
Effect and Remedies of Honeycombing in Concrete
As aforementioned, honeycombing in concrete is a very critical issue as it can affect the strength of the entire structure. Due to this, there are several effects that can be found in concrete.
- Moisture and chemicals can get inside of the concrete and it weakens the concrete bonding.
- Cause steel corrosion issue.
- Reduce structural compressive strength.
- Weakened structure load-bearing capacity.
- Form cracks.
Remedies for Honeycombing in Concrete
During construction, the honeycomb issue can be solved easily if you follow the construction code properly. And if somehow this issue happens then there is nothing to worry about as it can be solved quite easily.
Basically, honeycombing issues can be repaired by using construction grouts. For doing so,
- First you will need to prepare the honeycomb-affected surface.
- Remove the loosened aggregate and clean the surface.
- Dry the surface and then apply chemi-fix glue on the area.
- Now, take white cement and mix it with concrete grout.
- Apply the paste on the area and then cover the area with formwork.
Cure the area properly and then solve the honeycombing issue properly.
(FAQs) Frequently Asked Questions and Answers
How do I identify honeycomb in the inside mass of concrete?
You can see the honeycomb outside of the concrete with the naked eye but if it is inside the concrete then you will need to use technology. There is an advanced technique which is known as ultrasonic testing. By using this you can identify honeycomb inside the concrete.
How to prevent honeycombing in concrete?
There are a few things you will need to follow during construction. Such as; need to maintain the concrete fall height, need to compact properly, use proper sized aggregate, concrete is vibrated properly, and so on.
To sum up, the honeycombing issue is such a major concern in concrete. After identifying the issue, it’s mandatory to fix it as soon as possible. While fixing it, it’s better to seek help from a professional as it’s a very tricky job. However, you have failed to cure it properly then the issue will show up in the future again!