Honeycombing is a defect where voids or air pockets form in a concrete slab due to poor compaction, improper mix, or formwork issues. It leaves the surface rough, porous, and structurally compromised. If left untreated, honeycombing can allow water ingress, freeze-thaw damage, and even corrosion of embedded steel. In this guide, we’ll show you exactly how to assess and repair honeycombing — whether it’s cosmetic or structural.
Start by tapping the affected area with a hammer and inspecting visually. Light honeycombing affects only the surface and can be repaired with cosmetic patching. Deeper honeycombing, especially near edges or around steel, may require removal and rebuild. Check for exposed rebar, moisture ingress, or crumbling that signals poor compaction and full-depth damage.
Use a hammer and chisel or grinder to remove all loose, weak, or friable concrete. Don’t just skim the surface — open up the full honeycombed area to expose solid concrete. Feather the edges at a 90° angle to help your repair material bond properly. Vacuum out dust and debris thoroughly. For deeper repairs, remove to at least 25 mm depth or until solid material is reached.
Many polymer-modified or structural repair mortars require priming to enhance adhesion. Use a bonding agent, epoxy primer, or slurry coat depending on your product. Brush it deep into the surface and avoid pooling. Always follow the product datasheet — the right primer improves long-term strength and reduces failure risk, especially on vertical or overhead surfaces.
Choose a high-quality repair mortar or microconcrete with good adhesion, shrinkage control, and strength. Trowel or pack the mix firmly into the void, working it into edges and around any rebar. For deeper repairs, apply in layers or use formwork as needed. Compact the material well to eliminate new voids. Smooth the surface with a float or trowel to match surrounding concrete.
Cover the repair with damp cloth, curing sheet, or apply a curing compound immediately after finishing. Curing reduces shrinkage, cracking, and surface dusting — all of which can undo your hard work. For cement-based repairs, cure for at least 3–5 days. Avoid foot traffic, harsh sun, and drying winds during this period. Proper curing makes your patch last and bond as intended.
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