Repair cracks in concrete

Do DIY like a pro — our expert Henry Durham gives step-by-step guides to successfully carrying out a string of tasks and what tools and materials you need.

When concrete is exposed to repeated cycles of freezing and thawing during the winter months it can crack or spall (flake).

Uneven settlement of the soil beneath the concrete is another common cause of cracking.

But these cracks can be easily repaired with you needing expert help.

To mend a small cracked area of concrete, you need to remove the damage and patch it with a cement-based patching compound.

Follow the steps below to have smooth surfaces again.

Step 1: Remove the damaged concrete.

Using the cold chisel, remove all cracked or crumbling concrete to a depth of about 1ins below the surface.

Wear heavy gloves and safety goggles to protect your hands and eyes from flying chips.

Step 2: Undercut the edge of the patch.

To form a key between the patch and the existing concrete, hold the chisel at an angle and undercut the edges of the area to be patched.

Step 3: Remove the debris.

Remove any debris with a whisk broom and then hose the patch area clean.

Keep it moist for several hours or overnight.

Sponge out any standing water before proceeding with the next step.

Step 4: Mix the patching cement.

In a small bucket or other container, mix one part portland cement and three parts sand with enough water in order to make a stiff paste.

In a separate container, mix a small amount of portland cement with enough water to make a cement ‘paint’.

Coat the edges of the patch area with the cement paint to serve as a primer.

After the cement paint, pack the cement paste firmly into the patch with a putty knife or trowel.

Cut deeply into the mixture to remove any air pockets.

Step 5: Fill and smooth the patch.

Level the mixture with a straight-edged concrete-finishing trowel.

Let the patch sit for about one hour, then float or trowel to match the surrounding surface.

Step 6: Cure the patch. After trowelling, let the patch sit for a couple of hours, then cover it with a sheet of plastic.

Hold down the edges with bricks or rocks.

For the next week, lift the plastic cover daily and sprinkle water on the patch.

Henry Durham is the assistant general manager at Gorham’s, St. John’s Road, Pembroke. Ask him or any of the staff in-store for further advice about DIY projects and the necessary tools and materials. You can also log on to www.gorhams-ltd.com.