DIY Concrete and Crack Repair for Patios, Walkways, and Driveways

Jim Mallery

This is the first in a series on dealing with concrete problems.

Concrete has an expansive range of applications--patios, walkways, foundations, retaining walls and countertops. But it also may be prone to problems, including crumbling (spalling), cracking, sinking and heaving, and staining. Concrete cracks, but you can usually repair it.

Cracks in walkways, patios, and driveways may be the most common concrete concern for a homeowner, especially as a house ages. Hardened concrete men will say there are two kinds of concrete: cracked and that which will crack. Fortunately, many crack repairs, while tedious, may not be too difficult.

A number of things often cause cracks on horizontal surfaces. Freezing water under the concrete may cause it to heave; a soft, improperly laid substrate may allow the concrete to flex excessively; heavy trucks may have stressed it beyond its capacity; and soil could be shifting or settling.

Tear the Concrete Out?

If you have extreme, wide cracking, with edges of the cracks at different elevations, you may have to tear out the old concrete and have a soil expert rework the sub grade and pour new concrete. You may have a bad base, and any crack repair may be superficial and allow the problem to return.

But if you have small cracks--up to a half-inch wide--with the edges at the same level, repairs should be possible.

Cracks that are an eighth of an inch or less are the simplest to fix. They should be cleaned--wire-brushed or scraped with a cold chisel--then hosed clean. A latex concrete patch can be injected or troweled into the crack and smoothed over.

Wider Cracks

If the crack is up to a quarter of an inch wide, it should be worked with a cold chisel to widen the bottom of the crack--that should help hold the patch material. Again, the widened crack should be sprayed clean with a hose. A concrete adhesive should be applied to the crack to help the patch adhere, and then a concrete patch compound worked into the crack. The patch should be leveled with a trowel. Cover the repair with plastic, and allow it to dry slowly.

A crack that is between a quarter of an inch and half an inch would be repaired in the same way, but you can fill the bottom half of the crack with sand.

Next: Cracks in walls may be more worrisome.

About the Author

Jim Mallery, a semi-retired journalist and onetime registered contractor, has extensive experience remodeling, repairing, and rebuilding homes.

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