How to Repair Cracks in a Concrete Retaining Wall

Lead Image
  • 2-40 hours
  • Intermediate
  • 40-2,000
What You'll Need
Plastic pastry bag
Mixing attachment
Wire brush
Shop vacuum
Metal putty knife

A concrete retaining wall is built to resist the weight of the soil and the subsequent pressure that gravity sometimes places on the soil. These are common on properties that are positioned on small hills. The concrete retaining wall is built to keep the soil that makes up the hill in place, defying gravity. The wall is kept together by rebar installed in the center of the concrete and spanning the height and length of the wall. Over time, the ground in which the wall is embedded can settle, and when this happens, cracks can occur. These cracks can weaken the concrete retaining wall, so follow the simple steps below to repair them.

Step 1 – Inspection and Cleanup

To begin, locate all of the cracks and make sure they are clean. Whenever you come across a crack, use the wire brush to clean it with it. This will remove any loose concrete. You can then use the shop vacuum along the crack to suck out any small pieces of concrete that may still be left. Do not go out of your way scraping the concrete as this will make matters worse. You only need to use a very light stroke, and the loose concrete will fall naturally.

Step 2 – Mixing the Mortar

Mortar is essentially concrete that you will mix and then use to fill the cracks in the concrete retaining wall. It will adhere to the rough concrete in the crack—which, after it cures, will be just as strong as the rest of the wall. The easiest way to mix mortar is to follow the instructions on the packaging. Place the mortar in the bucket, and then add the specified amount of water. Install the mixing attachment on the drill, and use that to mix the water into the mortar. It generates enough speed to mix it thoroughly. Once the mortar reaches the consistency of smooth peanut butter, it is ready to be used.

Step 3 – Repairing the Cracks

Slapping mortar over a crack does not do as good a job as sealing it as the mortar will essentially be on the surface of the concrete. The pastry bag technique is a unique solution to this problem. Fill the bag about halfway up with mortar, and then twist the top of the bag closed and fold it over. Cut the tip off the bag. Place the tip at the top of the crack, and then squeeze the top of the bag with one hand while you steady it with the other. Move the tip along the crack as you squeeze and continue until the mortar overflow the crack. Use the putty knife to spread the mortar smooth. Repeat with the other cracks. It will take a day or two for the mortar to cure.