Pebble Tec Repair Aggregate - Try fish tank rocks?

[CA_Tallguy]

Hey everyone -- just posting this to see what people think, and to see -- does anyone know a good recipe for pebble cement mix? I have watched a bunch of YouTube vids and there seem to be two ways to do this (1) mix the aggregate right in and trowel the whole thing, or (2) cover the surface and trowel. Either way, the finishing step is to rinse and possibly acid wash to expose the aggregate.

There are a variety of pebble finishes such as PebbleTec and PebbleCrete out there but a large portion of what is in them is the aggregate. I suspect many of the cement mixes are quite similar.

When in need of a patch, there are systems such as EZ-Patch and Pool Patch. Again, they probably use a fairly standard concrete mix, maybe with some admixtures. They charge $10 to $20 per lb for the repair material and a large portion of that weight is the aggregate. Needless to say, the cost of any component in the mix is likely a tiny fraction of that cost.

You can buy 20# bags of aggregate for fish tanks for about $1 per lb. Take a look at the pretty decent match between this "New Zealand River Gravel" and our Pebble-Tec finish! Not bad, maybe a little more white in there than we have, and maybe the aggregate is a tiny bit larger on average in appearance. Maybe that will be less pronounced with some cement around/between. While the Quikrete coloring looks very very red, it's actually their "Buff" color and is supposed to be pretty mild and neutral when mixed.

If I could add in a bag or two of uniform color, neutral aggregate then this might be perfect. But I think the bonding concrete might also tone down the speckle quite a bit too.

 

[JoyfulNoise]

Your cement needs to have a waterproofing additive mixed into it as pool plaster is designed to be the waterproofing layer (gunite is not water proof). So whatever cement you use, I suggest you look into waterproofing additives.

Fish tank gravel and aggregate may look the same but the underlying stone material may not be the same. In a fish tank, you can have stones that contain calcium/magnesium/iron minerals. In a swimming pool, you really want silicate based aggregate as that is more chemically resistant and you definitely don’t want anything with iron in it. Colors are varied by the pool plaster manufacturer to achieve the desired look.

If you plan to use colorants with plaster then you should choose only those compounds that are color-fast and won’t be bleached out by sun and chlorine. Organic pigments are cheap but they are not color fast. Blue organic dyes tend to fade the most.

Perhaps @onBalance can offer some suggestions.

 

[CA_Tallguy]

Thanks @JoyfulNoise - do some of the pebble systems put waterproofing behind the pebble layer? From watching a bunch of applications on youtube I vaguely recall seeing that done in at least one of them. I'm about to go outside and put on some Sika 107 under a swim up bar to finish off and waterproof a repair and I could imagine something like that being put underneath some pebbles.

 

[JoyfulNoise]

Thanks @JoyfulNoise - do some of the pebble systems put waterproofing behind the pebble layer? From watching a bunch of applications on youtube I vaguely recall seeing that done in at least one of them. I'm about to go outside and put on some Sika 107 under a swim up bar to finish off and waterproof a repair and I could imagine something like that being put underneath some pebbles.

The tile guys usually waterproof the bond beam and down the wall just enough to cover the area where the water line tile sits and maybe an inch or two below that. The plaster guys don’t apply waterproofing typically. If it’s a new build, then the plaster will bond well to the gunite. If it’s a remodel they might might apply a bonding layer before plaster depending if it’s a skim coat versus a full chip out.