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Difficulty: Beginner
Gaps between concrete slabs are known as expansion joints. They help prevent cracks by allowing concrete to expand and contract.
These gaps might appear unsightly, so filling them with a flexible foam and sealant can improve appearance and help prevent water ingress, weeds and pests.
Steps
Step 1
Clean the crack.
Clean any dirt or debris from the crack using a brush, leaf blower, vacuum or a combination of these tools. Removing debris provides a clean surface that allows the sealant to form a solid bond.
Step 2
Cut and install the filler foam.
Lay out and cut the filler foam to length. Depending on the depth of the crack, you may need to cut the foam with a retractable knife or scissors to suit both length and height.
Compress and push the filler foam into the gap using a narrow tool such as a screwdriver or scraper. Ensure the foam sits 5-10mm below the surface of the concrete.
Step 3
Apply the adhesive sealant.
Cut the nozzle with your tin snips or retractable knife, so it is wide enough to apply a bead that will almost fully cover the width of the crack. Ensure you wear eye protection and cut-resistant gloves.
Cut the Sikaflex sausage end to open it. Insert the sausage into your caulking gun with the nozzle.
Apply the sealant to the gap, working backwards towards yourself. Once you have reached the end of the gap, look back along your sealant. If there are any low spots, apply more sealant to that area.
Step 4
Smooth off the sealant.
Place a soaking wet rag over your finger, then run along the sealant line to smooth the sealant into one uniform, unbroken bead covering the entire gap.
Repeat on any other expansion joints and admire your work.
Materials
Tools
- Brush, blower or vacuum
- Screwdriver or scraper
- Caulking gun
- Retractable knife or scissors
- Tin snips
- Bucket
- Rag.
