How To Fix Spalling Concrete in Your Driveway

What Is Concrete Spalling?

When concrete surfaces start to deteriorate, it’s called “spalling”. When you notice concrete flaking, chipping and cracking, that means your surface is spalling. It’s more common in colder climates, where the freeze-thaw cycle accelerates the process.

What Causes Spalling Concrete?

Spalling concrete is often caused by an installation mistake. Common mistakes include adding too much water to the mix to make it easier to pour, sprinkling the surface of the concrete with water to extend the finishing time, and not curing the concrete properly after installation.

It can also result from freezing. Concrete is porous, so when water seeps into the surface and freezes, it expands, causing the concrete to crack and flake. Deicing salts can also cause the concrete to deteriorate, leading to spalling.

How To Prevent Concrete Spalling

• In addition to proper installation, it’s important to seal your concrete surfaces with a waterproof sealant.
• Repair concrete cracks and other damage immediately. Cracks and holes in your concrete will expand rapidly as more water seeps into the surface, so grab some concrete crack filler at your nearest home center.
• The safest deicers for concrete are calcium chloride (the most popular deicer), magnesium chloride and potassium chloride.
• Use concrete-safe cleaners.
• Use low-permeability concrete, which will help prevent spalling by reducing the amount of water a surface can absorb.

How To Fix Spalling Concrete in Your Driveway

Resurfacing your driveway, patio or basement floor with a 1/2-in. concrete overlay fixes the problem. Enlist a couple of helpers and overlay the concrete surface one section at a time. A section is an area about 10 x 12 ft. that is defined by the existing control joints.

Before starting, power wash the entire surface and brush it with a stiff broom and a cleaner/degreaser concentrate available from the hardware store.

The technique we show below can be modified for resurfacing concrete patios and basement floors.

Stake 1×2 furring strips along the edges of the driveway or patio, keeping them 1/2 in. above the existing surface.

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“Picture frame” the section by nailing 1/2-in. plywood strips, flat to the concrete, along the control joints.

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Mix one part Type 1 Portland cement and one part fine sand by volume. Add water until the mixture is the consistency of thick paint, then brush it on the damp concrete.

Before that dries, mix three parts fine sand and one part Portland cement in your wheelbarrow with enough water to make the mix the consistency of thick oatmeal. Shovel the mix into the formed area and level it with a straight 2×4 spanning from one side of the forms to the other.

Smooth the surface with a bull float, round the edges along the forms with an edger, and finish the surface with a finishing broom. Timing is the secret to getting a nice finish. Use the bull float immediately, but wait until the concrete stiffens before using the edger and broom. All the tools you need are available at most rental stores. Cover the finished concrete with plastic for five days or spray it with a curing compound.

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