This project explains how to repair a large wide crack in my patio concrete slab with Emecole 555 Fast polyurea resin. The concrete slab cracked, sliding downhill by 1/2″ and tilted up about 3/4″ as shown due to soil settling and the weight of the poured concrete steps on this 5 foot wide section of patio. I felt that surface patching would be insufficient and chose the Emecole 555 polyurea to create a structural repair that would bond the concrete slabs together to the full depth of the crack.
Why the Concrete Slab Cracked
I later discovered during the sagging wood deck repair project the patio slab had been poured without proper footers, rebar and remesh wire. The slab was just poured on the ground without reinforcement which allowed it to settle and crack. The former homeowners liked to do things cheaply without building permits and inspections, which allowed the contractor get away with shoddy work.
- No footers.
Footer should be set at least 12 inches deep below ground level to be below the frost line. The frost line is 12 inches in my area.
- No rebar is present in the slab perimeter where the footer would be.
- No remesh reinforcing wire was laid in the slab interior.
Concrete Repair Options
The following table summarizes several QUIKRETE® concrete repair products that are widely available at home improvement stores with the Emecole 555 Fast polyurea resin system. Given the 6″ to 10″ deep by 1/2″ to 3/4″ wide crack in my concrete patio slab, the two choices for this job were the QUIKCRETE Vinyl Concrete Patcher No. 1133 and Emecole 555 Fast.
I decided against concrete for the following reasons:
- Concrete is relatively weak in tension (pull apart) strength and couldn’t prevent the slab from shifting again.
- It would be difficult to work concrete to the full depth of the crack, resulting in air pockets and voids.
- I had doubts the “cold joint” between the new concrete filler and the slab wouldn’t crack again.
Aside: If structural issues are concern that threaten the house, a concrete foundation can be raised with helical piers.
I happened upon the Emecole 555 product after an extensive on-line study of concrete slab crack repair products and techniques. I felt comfortable choosing Emecole after reading their extensive online literature and called Emecole to verify it was suitable for my particular problem.
Emecole 555 Fast polyurea resin appeared to be ideal because:
- It is very strong in tension strength. At over 4000 PSI, Emecole is stronger than concrete.
- It is a thin liquid that penetrates deeply into the crack, filling all voids.
- It soaks into the concrete to form a high strength chemical bond.
- The sanded and cured material is similar to concrete in texture and color.
If you already have the “Jake” tool dual-cartridge dispensing gun, the refill kits are less expensive.
Emecole 555 has a shelf-life of 1 year. If you follow the dispensing instructions to avoid cross contamination, a cartridge pack can be partially used, capped off and saved for later.
Emecole 555 Concrete Slab Large Crack Repair Video:
Small & medium Crack Repair Kits are available in single tube containing both resin and hardener for use in a standard caulk gun:
Consider the depth of the concrete crack because a deep crack will require more Emecole 555 material to repair.
Concrete Slab Crack Repair with Emecole 555
End of the patio had lifted about 3/4″ when it cracked and shifted downhill from the main slab. The raised lip created a trip and fall hazard, so I needed to bevel it to make a smoother “ramp” transition.
I chipped the high side of the cracked slab with a brick chisel and 3lb sledge hammer. This worked really well and went quickly.
After some rough shaping with the brick chisel and cleanup with a shop vac, I ground the high side of the crack smooth with my 4.5″ Dewalt Angle Grinder fitted with a masonry wheel. I was very pleased at how quickly the angle grinder knocked down the concrete lip. I’m maybe 10 minutes now into the job, things usually take longer than this. Dust wasn’t bad and a light breeze keep the air fresh.
Fill the Crack with Sand
The repair technique for a large deep crack differs a bit here from a more typical narrow crack. If I were to squirt the Emecole 555 into the crack to prime the concrete slab, it’d be like trying to prime the Grand Canyon; the Emecole 555 would just run out the bottom instead of pooling in the crack.
For large cracks such as this, the Emecole representative said to partially fill the crack with sand, then apply the Emecole 555. The Emecole 555 will then saturate the sand and slab instead of running out the bottom of the crack.
I poured 14 cups of sand in the crack to bring to within 1″ of the slab surface!
After filling the crack to about 1″ of the slab surface, I ran the shop vac along the crack to pull out the high spots and level the sand. This created a 1″ to 1-1/2″ deep channel (important!) to hold the Emecole 555 in the crack so it can soak into the sand and bond the crack.
Fill the Concrete Crack with Emecole 555
Emecole 555 begins to gel in about 3 minutes after it’s applied, so you need to plan your work and have your tools ready:
- Bag of sand
- Cups filled with sand
- 3″ inch putty knife
- Waste can for excess Emecole scraped up with the putty knife
The Emecole 555 was simple to apply as I filled the channel. Emecole has low viscosity (i.e. runs like water) and soaked right into the sand. I made several passes with the dispensing gun, refilling the crack.
This project is continued in Concrete Slab Crack Repair – Part 2.
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