Concrete Pitting Prevention & Repair

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Does it look like your concrete has been pelted all over by tiny meteorites? The most likely cause is concrete pitting—small, crater-like holes that form on the surface, making it rough and uneven. This defect most commonly occurs in surfaces exposed to harsh environmental conditions, moisture, and freeze-thaw cycles.

Outdoor concrete like driveways, sidewalks, patios, and pool decks are more prone to pitting. However, indoor floors can develop it too under certain circumstances. Pitting takes away from the appearance of your concrete and weakens the surface leading to damage. Knowing what causes pitting and how to prevent or fix it can help your concrete last longer and look better.

What does concrete pitting look like?

Pitting appears as small, shallow holes on the concrete surface. These pits often form in clusters, creating a pockmarked look. The pitted areas may also show some discoloration compared to the rest of the concrete, appearing darker or lighter. Pitting can appear within months of concrete placement or take years to develop, depending on concrete quality and exposure to the elements.

Concrete pitting is sometimes mistaken for popouts. These look-alike imperfections are characterized by small cone-shaped cavities in the concrete. Unlike pitting, popouts occur when aggregate pieces near the surface absorb moisture, expand, and break away. They typically appear within the first year after concrete placement and are usually just a minor cosmetic issue.

What causes concrete pitting?

Pitting of concrete has a variety of causes, ranging from environmental factors to material and construction issues. Some of the most common include:

• Repeated freeze-thaw cycles. Water seeps in, freezes, expands, and breaks away the surface of the concrete.
• Exposure to salt and deicing chemicals, which are absorbed into the concrete and weaken the surface.
• A bad mix that results in weak, porous concrete more susceptible to pitting (see Concrete Mix Design).
• Inadequate curing, which may prevent the concrete from achieving its full strength and durability.
• Improper concrete finishing techniques, such as over-troweling or not waiting for bleedwater to evaporate.

The causes of concrete pitting can also lead to spalling, cracking, delamination, and efflorescence. It is especially important to take preventive measures, so you can minimize the risk of multiple types of damage.

How do I prevent concrete pitting?

Preventing concrete pitting involves a combination of good mix design, proper concrete placement and finishing techniques, and regular maintenance.

First, be sure to use the recommended proportions of water, cement, and aggregates in the concrete mix. A low water-cement ratio is especially important to ensuring a strong, durable concrete surface that is less prone to pitting.

After the concrete is placed, proper curing is essential to give the concrete the moisture it needs to attain full strength. This means keeping the surface moist for at least seven days, using methods like water curing or the application of a curing compound (see Guide to Concrete Curing Time & Methods).

To protect your concrete from chemical exposure and water damage caused by freeze-thaw cycles, apply a high-quality concrete sealer. Don't forget to reapply every few years to maintain protection. Also minimize the use of deicing salts, especially during the first winter after the concrete is placed. Instead, use ice melt products that are less corrosive or apply sand or another abrasive material to improve traction (see How to Melt Ice on Concrete Without Causing Damage).

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Can pitted concrete be repaired or resurfaced?

Yes, you can (and should!) repair pitted concrete. The pits can serve as entry points for water and corrosive substances that can lead to further deterioration.

For minor issues, filling the pits with a polymer-modified cement patching compound will usually be sufficient. If the pitting is extensive across a large area, apply a concrete resurfacing product to completely restore the concrete’s appearance (see Concrete Resurfacing).

Before fixing pitted concrete, proper surface preparation is essential for a successful repair. If necessary, use a chisel and hammer to remove any loose or damaged concrete. You want a solid edge for the patching material to bond with. Then thoroughly clean the surface using a pressure washer or a scrub brush along with a concrete degreaser. Dirt, oil, grease, and stains can interfere with the adhesion of the repair material.

How do I smooth a rough and pitted concrete floor?

The most effective method is to use a concrete grinder to grind down the surface and remove the pitted areas. Because the depth of removal when using a grinder is limited to about 1/8 inch, you'll need to fill any deeper pits that remain with a concrete patching compound. You can then grind the surface again using a finer-grit grinding disk to blend the patched areas with the rest of the concrete.

If you have large areas of shallow pitting, then a polymer-modified floor overlay or topping may work well. Choose one that goes down at at least 1/4 inch thick and hides minor surface imperfections (see our comparison chart of concrete overlay systems).

What’s the best patch for pitting on stamped concrete?

When repairing pitting in decorative stamped and colored concrete, achieving a seamless match can be tricky. To minimize the visibility of the repair, use a patching product that can be tinted or comes in a color close to your existing concrete. It’s often best to consult with a professional who specializes in stamped concrete repair.

Can I repair concrete pitting myself?

You can definitely repair concrete pitting yourself, especially if the damage is minor and you have some basic DIY skills. However, if the pitting is widespread or the concrete shows other signs of damage that could indicate an underlying structural issue, you should call on a professional to assess the severity of the problem.

If the best solution is to resurface the pitted concrete with an overlay rather than patching the holes, hiring a professional concrete resurfacing contractor is usually the better way to go. Experienced resurfacers can achieve flawless, long-lasting results (see Why DIY Concrete Resurfacing Isn’t an Easy Project).

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