Gunite core sample test

[joliecher]

We are just about to start plaster on a new gunite pool and I was squirting off the mud and extra mortar when I saw two cracks on the stairs.

Squirting more water, I was able to go down about 5 inches with just hose pressure and it is not holding water. I believe this area was hand packed. Another area has sand like consistency where they had to dig up a pipe. It has been about 6 weeks so I would think it is cured.

Where can I send a sample off to insure it is strong enough?

[Titaniumboy]

joliecher,

It sounds like your pool builders shotcrete subcontractor used "rebound" to form the steps. Using "rebound" is absolutely forbidden in normal shotcrete jobs, but seems to be endemic in pool construction. Also the shotcrete that is "trimmed" during finishing operations from the walls, etc is often reused to form benches and spas. This material, like "rebound" is not suitable for reuse.

"Rebound" is the shotcrete that does not adhere directly where it is sprayed. It is the stuff that bounces around and ends up on the floor. "Rebound" and "trimmings" should NEVER be used and should always be hauled away as debris.

Here is a great article about the problem. http://www.shotcrete.org/pdf_files/Spring07%5FLacher%5FDryMix%2Epdf

Titaniumboy

[bobyoe]

Don't know about shotcrete, but you could look for a concrete testing laboratory. If it's like concrete, they will come and drill out a core sample, send it for testing and charge about $1500 for the analysis.

[aylad]

I would absolutely point this out to your pool builder...if it's not holding water, then it's not strong enough and you shouldn't have to settle for cracks in a brand new pool.

Janet