How to Repair a Cracked Concrete Patio – insert backer rod, caulking and sealing the cracked patio. This project is continued from How to Repair a Cracked Concrete Patio – Part 1.

Table of Contents

  1. How to Repair a Cracked Concrete Patio
    • Surface repair technique with concrete repair caulk.
  2. How to Repair a Cracked Concrete Patio – Part 2 (this project)
  3. Concrete Slab Crack Repair
    • Large crack structural repair with polyurea resin and sand for a hard durable surface.
  4. Concrete Slab Crack Repair – Part 2

After applying a bead of the QUIKRETE® Concrete Repair (No. 8620-10) sanded caulk, work it into the crack with a fingertip to seal it against the concrete.

Smooth the QUIKRETE 8620 Caulk into the Concrete Crack

Finish the Concrete Caulk Line

The caulk line now has a U-shaped depression from your fingertip that must be filled to prevent water from pooling in the crack and to present a even surface for a nice looking appearance.

  1. Apply a 2nd thin layer of caulk along the crack.
  2. Pull a putty knife along the crack to smooth the caulk.
  3. Push the putty knife over crack to scrape away the excess caulk.

Scrape Off the Excess Concrete Caulk with a Putty Knife

The crack narrowed as it approached the house. No backer rod is needed when the crack narrowed to less than 1/4″. The crack is fully caulked and finished in this photo.

QUIKRETE 8620 Caulk, Backer Rod and Tools for Cracked Concrete Repair

The crack will be stained to blend with the rest of the patio concrete after it cures.

Patio Slab Edge Repair

The crack in the outside edge of the patio slab is patched using the same method with backer rod to fill the crack and QUIKRETE 8620 caulk.

The foam backer rod is pressed into the surface of the crack:

Cracked Concrete Patio Slab – Corner Repair

The backer rod is seated with a screw driver:

Backer Rod Filler Seated in the Cracked Concrete Slab

The crack is caulked and smoothed with a fingertip:

Concrete Crack Filled with QUIKRETE 8620 Caulk

A second thin bead of caulk is applied, then smoothed and scraped with a putty knife.

Finished Crack in the Patio Concrete Slab

QUIKRETE Concrete Repair Results

The QUIKRETE Concrete Repair No. 8620 caulk did a good job at an unbeatable price. Easy to apply with simple tools and has the sanded texture of concrete. I needed only one 10oz tube to patch the 13 foot long crack. The patch will not be noticeable when I apply a new coat of concrete stain.

My patio slab cracked because the soil foundation settled. I believe the soil and slab movement has stopped as the house is 10 years old. Caulk is best suited for stable slabs and cracks where a weather-seal will suffice. I’m curious to see how well the caulk will hold up over time and if peeling will be an issue.

Emecole 555 – Concrete Patio Large Crack Repair

The other end of my concrete patio slab has a large 1/2″ crack where the poured concrete steps have pulled away. Caulk and concrete would be insufficient because a high strength structural bond is needed glue the slab back together to prevent further movement. I used the Emecole 555 polyurea DIY Slab Repair Kit to mend the slab:

Emecole 555 polyurea Concrete Slab Repair Kit

See the Concrete Slab Crack Repair project for more about Emecole 555.

Take care,

Bob Jackson

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