Concrete Repair 101: Driveways, Sidewalks, and Around the Home

Most concrete fixes around the home can be DIY projects. Artazum/Shutterstock

Few things negatively impact curb appeal as much as a cracked or crumbling sidewalk, walkway, or driveway. Breathe easy! Most concrete fixes can be DIY projects, including porches, backyard patios, planter boxes, and vertical patches on the home’s exterior.

Don’t procrastinate, though, as harsh winter weather will only make things worse. Fall boasts the ideal temperature range for concrete repairs—between 45 degrees F and 75 degrees F. You also want the property to look its best for the family and friends stopping by during the holiday season.

For those lucky enough to have concrete in great condition, it may only need to be sealed so that it doesn’t absorb water and liquid and deteriorate over time. Give it a good pressure wash first, because this not only removes dust and debris and allows the sealer to adhere better, but also exposes small cracks and other hidden damage that need to be repaired. Let it dry completely, then apply a high-quality concrete sealer, available tinted or clear.

The exception to this rule is the public sidewalk that crosses the front of many homes. Sealers can make a concrete surface slightly slick (or very slick with a gloss coat), so annual maintenance of the public sidewalk, which is the responsibility of the homeowner in most municipalities, is normally limited to pressure washing.

Perfect Finish

Fine surface cracks, particularly on newly-poured concrete, may mean that it simply cured too quickly. These are normally cosmetic and are not a sign of serious structural damage. Simply apply a thin layer of a resurfacing product with a trowel to the affected area, and feather (seamlessly blend) the edge into the existing concrete.

Resurfacers are designed to bond to the existing concrete, correcting imperfections up to a half-inch in depth. Unless you’re using it in a garage or an enclosed patio, make sure the product is rated for exterior use. For the exterior walls of a home, use an early strength-gaining, polymer-modified, cementitious patching material, designed specifically to adhere quickly and firmly to vertical and overhead surfaces.

Cracks? Potholes? No Problem

Cracks smaller than one-quarter inch can be easily filled with a flexible-formula liquid masonry crack filler, available in handy squeeze bottles and caulk tubes. Clean out the crack thoroughly, using a screwdriver to remove any loose concrete or repair material. Pressure wash the driveway if it hasn’t been done already. Let it dry thoroughly, then fill until even with the existing concrete. Smooth if necessary.

For deeper, but thin cracks, or those one-half inch wide or slightly larger, insert a flexible backer rod first. This may require opening up the crack slightly to fit the backer rod securely. Then use a trowel to apply a pre-mix or mix-it-yourself concrete patching compound, pressing it in until it makes firm contact with the backer rod. Then fill until it is level with the existing concrete.

Cracks two inches or larger—particularly those with large pieces of crumbling concrete that need to be removed—may require cleaning down to the hard-packed construction sand (driveway) or dirt (walkway) below and re-pouring (filling) with a patching compound that contains gravel.

To simplify matters, mix the compound in a 5-gallon bucket, using a paddle mixer that works with an electric drill. Press in firmly until it is level with the surrounding concrete, and scrape off the excess. This works for potholes too. Use a sand mix for small holes that do not need to be cleaned down to the substrate, or a gravel mix for larger or deeper holes.

When working on a driveway or walkway in particular, it’s best to use rapid-set materials to get the area back in action as soon as possible.

Vertical Work and Edges

Most half-inch vertical cracks, whether on the house wall, steps, or a concrete planter box, can be quickly repaired with a concrete repair or polyurethane sealant in a caulk tube. They will not need the foam backer, and they’re not subject to the same freeze/thaw and weight-bearing requirements of a driveway, walkway, sidewalk, or patio. Cracks smaller than a quarter inch should be widened with a chisel and filled with a textured acrylic caulk.

Cracked, pitted, and crumbling edges of steps, curbs, and porches may require a frame to temporarily hold the repair in place as it cures. This can be as simple as placing a 2x4 or piece of cut-to-size plywood running along the outer vertical edge of the project area, held in place with bricks. Clean the cracked, pitted, or crumbling concrete thoroughly, and set the frame in place. Mix a vinyl patching compound (this replaces the need to mix regular mortar with a bonding agent), tamp it into place to eliminate air pockets, and smooth it to the level of the existing concrete. Save some mix to make up a small batch for any minor cosmetic fixes that may be needed after the frame is removed.

Once the concrete is rejuvenated, upkeep, if addressed promptly, should be minor.

Safe Stepping

Sidewalks can settle and shift over time, leading to an uneven surface and tripping hazards. Here are three repair options to choose from.

Rent a Grinder

Uneven slabs with a difference of 1 1/2 inches or less can be shaved down until even. Grinding is highly efficient, but the downside is the resulting slab is thinner, weaker, and more subject to freeze-thaw, which is why 1 1/2 inches is the limit.

Lift to Level

Mudjacking is the process of drilling holes through a sunken slab and then pumping a concrete mixture underneath with a grout pump hose, causing the slab to rise back into position. Fill the drilled holes with extra concrete, and scrape with a wire brush so the texture matches the surrounding concrete.

Add More Concrete

Sunken pavers can be topped up with a patching compound until they are even with the adjacent section. For a ground heave (lifted up) paver, add “ramp up” material from the lower section to the higher section to create a smooth transition. The downside is that these repairs may eventually crack or chip.