Repair of fine crack in gunnite tub

This is not a small crack. It appears that the RBB is has structural damage from movement. A DIY repair is not going to fix the reason for the movement. As a temporary patch a hydraulic cement and still would not have much faith in duration of the repair.

Looks like it needs staples.

A flexible marine sealant might work but you need to clean out the crack so it can adhere properly.

Bperry said:

Looks like it needs staples.

Click to expand...

Concrete staples may be required to repair. You only know once you dig into it and see the size and depth of the cracking.


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Concrete Crack Repair Staples for Swimming Pools and Pool Decks | AquaStitch

It's definitely structural going through the bond beam and gunite.

In my opinion, staples are not going to do much if the gunite is cracking due to the shell settling.

If the force caused 9" of reinforced gunite to crack open, some staples or glue won't be strong enough to stop further cracks.

You can cut the crack and patch with plaster, but any repair like staples or epoxy injection isn't going to stop the force of the shell settling.

Unless you can address the cause of settling, there is nothing that will keep it from opening up more.

If you have two halves of a pool, the gunite is maybe 100,000 lbs per side plus the water weight/pressure.

Unless the ground is holding all of the force or 99.999% of the weight, there's no way that any type of repair could hold that type of force.

Even if the staples were unbreakable, the concrete they go into would crack open under that much force.