In the Northeast, the freeze-thaw cycle can be tough on hardscaping. As the ground freezes each winter, it pushes rocks and other obstructions upward, causing cracks and heaving in patios, walkways, and other masonry surfaces. When a homeowner experienced some walkway damage, she called the Ask This Old House team and Mason Mark McCullough knows the perfect solution.
How to Repair a Concrete Walkway
- In most cases, you’ll be able to cut along the expansion joints. However, if there aren’t expansion joints, snap a chalk line on either side of the damaged area.
- Use the circulate saw with the masonry blade to cut along the chalk lines. Use the wet/dry vacuum to collect the dust while cutting. Note: Be sure to wear ear, eye, and breathing protection while cutting.
- Use the sledgehammer to break up the concrete pad. Remove all of the rubble and broken concrete.
- Inspect the ground under the walkway for large boulders and other debris that could heave and push against the concrete. Remove anything that could cause damage.
- Empty the crushed stone into the walkway space. Use the tamp to compact the stone into place. If necessary, use a bit of water to lubricate the stone and make it easier to compact.
- Using the existing pads on either side of the repair area as a guide, cut and install 2×4 forms. The top of the forms should be flush with the tops of the other pads. Install rebar on the outside of the forms for support, and ensure their tops are below the forms. Place a piece of number 9 wire between the forms.
- Mix concrete in the wheelbarrow by emptying the bag of concrete mix into the wheelbarrow and slowly adding water. Mix the two with the shovel, and attempt to achieve a stiffer mix that won’t run much. Pour the concrete into the repair area. Repeat until the forms are full.
- Use a 2×4 cut about 2 feet wider than the repair area. Place it on top of the forms and shimmy it back and forth to level the concrete. Fill any low areas with extra concrete and screed again.
- Use a magnesium float to smooth the surface of the walkway and bring the cream of the concrete mix to the top.
- As the mix begins to stiffen, use the edger to cut along the forms and the joint tool to cut the expansion joints. Use the 2×4 as a guide for the joint tool.
- Use a damp sponge to dab the surface and remove any excess cream and expose the aggregate to promote grip and blend the new concrete in with the old concrete.
Resources
To demo the damaged walkway section, begin with making cuts on either side of the crack using a circular saw with a masonry grade blade. Use a HEPA vac to cut down on dust. Once the straight breaks are established use sledgehammers to break up loose pieces. Use shovels and a pickaxe to remove rocks.
To reestablish the base add a layer of gravel and hand tamp firmly into the ground until level. This will help with drainage and will absorb the pressure of a rock being pushed to the surface by frost.
To create the forms, use precut 2x4s. Jam one end of the 2×4 into the edge of the existing concrete using a hammer. By aligning the 2x4s with the existing concrete it creates a leveled pitch for the form.
Drive in a stake on the outer side of each 2×4 for extra support. Lay down wire mesh on top of the gravel to help resist cracking.
Use a concrete premix and add water. Mix in a wheelbarrow with shovels until desired consistency is achieved. Once the concrete mix is poured use a 2×4 to screed the concrete to a smooth and level finish.
To remove air bubbles, use a magnesium float. Sponge off excess moisture using a masonry sponge.
