What Is Concrete Honeycombing? How Do You Repair It?

By:    |   Published March 25, 2020
Concrete honeycombing protrudes from the corner of a new foundation wall.

Beekeeping has become a popular hobby. However, even if you’re an avid apiarist, the only place you want to see honeycombing is in your beehives. If honeycombing is discovered in the concrete of your foundation or other areas made of cement, it’s called concrete honeycombing and is worth inspecting to determine the severity and the potential danger it may cause your home.

The Cause of Concrete Honeycombing

The most common cause of concrete honeycombing is simple oversight. Whether in the mixing or pouring of the concrete, the source of honeycombing is generally shoddy craftsmanship or materials.

Some of the ways this worse-than-it-looks concrete honeycombing can happen are as simple as the wrong recipe. If the water and cement ratios aren’t correct, the result can be weakened concrete which often causes concrete honeycombing to occur. Not only does the size of the project matter in determining the proper recipe, but it is important to factor in the type of environmental exposure the concrete will face.

The correct recipe can also be a factor in reducing air bubbles. With any concrete job, handling air bubbles that occur is part of the territory. Air bubbles which are mishandled can weaken the concrete and, ultimately lead to concrete honeycombing if not properly addressed. One of the most common procedures for air bubble elimination is vibration. However, one must know how much vibration is needed because the mixture can become separated if too much vibration is used. Conversely, air bubbles will remain if not enough vibration is used to eliminate them.

Another factor that can have an effect on concrete and your foundation’s strength is the placement of reinforcement bars. Concrete may not fill in properly if the reinforcement bars – or rebar – are incorrectly placed.

Finally, the concrete recipe includes aggregate materials. According to cement.org, “Aggregates, which account for 60 to 75 percent of the total volume of concrete, are divided into two distinct categories – fine and course.” Sand and crushed stone are the main fine aggregates while gravels make up the majority of course aggregate materials. Poorly prepared recipes or improperly washed aggregates can result in an imbalance and a mixture that may be susceptible to concrete honeycombing.

Is Concrete Honeycombing a Cause for Concern?

Although concrete honeycombing is simply an issue of aesthetics more often than not, it doesn’t mean you can ignore it. Experienced contractors won’t sound the alarm if they discover honeycombing, but it is important to evaluate if there are any other issues that may result from it. If the honeycombing runs deep enough to expose rebar, concrete cancer can result. When rebar is exposed, moisture damage in the form of rust causes the concrete to be pushed away from the rebar. Cracking and, eventually, eroding concrete reduces the strength of the concrete and weakens the foundation.

It is also possible for moisture to get trapped in honeycombed areas which may result in mold problems. This doesn’t mean you need to evacuate, but a professional inspection is the best way to evaluate the extent of your concrete honeycombing and what steps may need to be taken if the structure of your home is in jeopardy.

How to Repair Concrete Honeycombing

When the occurrence of concrete honeycombing is determined to be simply a cosmetic issue, you may be looking at a DIY job. Similar to the repair of small foundation cracks, the honeycombed gaps can be sealed with epoxy and the area then waterproofed. Anyone not experienced in working with epoxy may want to have the repair completed by a professional.

When concrete honeycombing is beyond cosmetic and the repairs extend past simply sealing up the honeycombed section, an experienced professional is the best option in determining what course of action should be taken to protect your foundation. It’s never a good idea to take on a repair job without being competent and knowledgeable about the procedure, especially when the foundation of your home is involved.


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The best way to protect your home from water damage is with professional waterproofing. EverDry Toledo can help with a FREE 20-point basement inspection! We’ll help you find out if your home is at risk for water damage and which solutions will best serve you. Contact us online to schedule an appointment or give us a call at (419) 469-5833 and schedule your inspection today!

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