5 Simple Steps to Repair Damaged Concrete Expansion Joints

Concrete expansion joints, the gaps in between the slabs on your driveway or sidewalk, are there to prevent random cracking. Expansion joints are often sealed with an adhesive sealant, but these can wear out over time. Replacing them prevents ugly cracks and reduces the risk of costly repairs in the future.

For this DIY repair you will need:

  • Waterproof sealant
  • Caulk gun
  • Acetone
  • Utility knife or angle grinder (we recommend an angle grinder, but a knife works fine)
  • Foam backer rods
  • Rags (the more the better)
  • About two days of good weather

Getting to Work

Repairing expansion joint seals might seem like a daunting task at first, but it can be accomplished in a few simple steps.

Step 1: Using a utility knife, or angle grinder, remove the existing seal and clean off any residue with acetone. This step is the most important, and takes the longest. Be sure to wear the appropriate safety gear.

Step 2: Remove the old foam backing rod and clean out the joint with a shop-vac or leaf blower.

Step 3: Take the new foam backing rod and press it into the joint. The diameter of the foam rod should be a bit wider than the joint, ensuring a tight seal (this will also reduce the amount of sealant you need to use). Be sure the rod sits beneath the level of the concrete or you’ll have an uneven seal.

Step 4: Using the caulking gun, apply the new sealant in the joint. Try not to apply too much or too little. We recommend buying more tubes of sealant than you expect to use, you wouldn’t want to run out halfway through the project.

Step 5: The sealant should be dry in one or two days, but you’ll need at least 24 hours without rain to ensure a good seal. We recommend not driving over the seal for a few days so the sealant doesn’t track across the driveway.

Enjoying Your New Seal

Now that you’ve repaired your damaged concrete expansion joint, you can expect years of waterproof joints and minimal cracking. If this job seems out of your league or you have more serious concrete repairs, don’t hesitate to call the experts at Cornerstone Restoration.

Contact Waukesha concrete repair specialists for all your restoration needs.

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