What is honeycombs in concrete?
- When cement paste or concrete fails to fill up the spaces around coarse aggregate particles and reinforcing steel, hollow sections of concrete called honeycombs or rock pockets result.
- These gaps are dispersed over tiny localized areas and may be found in one or two locations, throughout the entire concrete surface, or perhaps even inside the member.
Where is the honeycomb found in the concrete structure?
What causes honeycomb in concrete?
- Poor workability of concrete – Consistency and cohesion are two components of concrete’s workability. The water cement ratio and aggregate cement ratio have a significant impact in influencing the workability of concrete. Low water content, high temperature, and an unsuitable fine-to-coarse aggregate ratio can result in poor workability.
- Defective formwork – Grout can seep through formwork joints or holes if the joints are loose or the formwork is not leak-proof. As a result, the grout will flow out during compaction, resulting in honeycomb in the concrete.
- Improper concrete compaction – In order to improve the density of the freshly poured concrete, air must be removed from the mixture and the aggregate particles must be compacted. Various techniques are used to compact the concrete. such as manual compaction, vibration-based compaction, etc. When concrete is compacted using the vibration method, excessive vibration leads to separated concrete. Similar to this, concrete that has been under vibrated will also allow honeycombs to form.
- Incorrect placement of the rebar or poor detailing – Because of inadequate detailing or poor and inefficient workmanship, reinforcement bars put too closely together or too close to formwork will entrap the bigger aggregate pieces.
- Concrete segregation – The separation of the components of freshly cast concrete is known as segregation. A concrete sample is not only weak if it begins to separate, but it will also develop voids or honeycombs.
Effects of concrete honeycombing
The water and air keep seeping inside the concrete if there is defect of honeycomb in concrete. As a result, reinforced concrete structures eventually lose their strength and ultimately their ability to support loads. This will lead to problem of structural integrity and frequent repair is needed.
Why it is necessary to repair the honeycombed concrete?
The answer is “Yes”. If concrete honeycombing expands to large area, exposes steel bars, and penetrates 5 cm or more into the concrete, it can be very problematic.
Repairs need to be made as soon as feasible to the damaged area. It changes structural members’ appearance as well as their strength and durability, shortening their useful lives.
What are the steps required to repair the honeycombed concrete?
The steps in a honeycomb concrete repair process are to remove any loose material, clean the damaged area, apply the correct repair materials, grout where necessary, and cure. Let’s take a step-by-step look at the concrete.
Step 1: Visual inspection or a non-destructive test, such as the Impact-echo test, can be used to determine the size and depth of the honeycombed area. You can also inspect and hit the hammer of blows. If it makes a hollow sound, the area there has honeycombing.
Step 2: Use a hammer or wire brush to remove all the loose materials and dust from that area before starting any repairs. Avoid using strong forces, such as electrical chippers, at this stage of concrete honeycomb repair to prevent concrete damage around the honeycomb area.
Step 3: Before making repairs or replacements, wet the concrete surface.
Step 4: If the honeycomb area is tiny and the reinforcement can be protected by the concrete cover due to its quality, it can be repaired by patching with mortar of similar color to the base concrete.
Step 5: Cutting away the defective concrete and replacing it with new concrete that has been coated with the proper bonding agent is required if the honeycomb covers a substantial area and has reached the reinforcement or deeper.
Step 6: If voids are dispersed throughout and deep inside, grouting is definitely necessary. Place formwork if required before pouring the grout. Apply the appropriate repair material, such as non-shrinkage concrete grout, high strength concrete grout, etc. by grouting, if formwork is not employed.
Key Takeaways
Reinforced concrete has always been regarded as a long-lasting structural material. However, concrete defects or damage are a result of the material’s limitations as well as a number of other factors, including harsh environmental conditions, bad design, inadequate detailing, and poor building techniques. The honeycomb defect in concrete is one of the critical defects that require immediate attention. To reduce the likelihood of concrete honeycomb, take the required actions listed above as soon as possible.
Therefore, Structural Repairs (M) Sdn Bhd, a qualified contractor that can assess the severity of your honeycombed concrete problems and recommend the best course of action to you.
Please do not hesitate to contact us if you require more information. Our team will be happy and glad to assist you.
Kindly visit to our website at https://structuralrepairs.com.my/ or contact us at Tel: +603-91731728/29 Whatsapp: +60 12-334 9113
