PVA admix in plaster scratch-coat/undercoat?

[tomfrh]

We'll be replastering our pool at some stage. Some of the contractors I've spoken to mention using PVA admix as bonding admix agent in the sand/cement undercoat/scratchcoat, beneath the final pebble plaster. (Not sure if they add PVA to the final coat too).

Here is an example product: Cemstik®

However, looking at these products they say NOT to be used in permanently immersed applications?

Anyone have any advice here?

 

[bdavis466]

I would only use Basecrete ?

Basecrete

 

[tomfrh]

Yeah I've been investigating that. I may order some (we're in Australia).

But even so, people seem to use these PVA admixes as part of their pebble system. I'm trying to understand how it can be used when manufacturers say not to use in immersed applications.

 

[bdavis466]

They are either using the product incorrectly or are assuming the plaster is waterproof and it shields the bond coat.

 

[tomfrh]

I did some tests with the PVA bondcrete admix, and compared to waterproof latex admix. They both stuck very well compared to plain water, both initially, and after a week of immersion.