“Faux Rock” material?

atropine

Member
Feb 4, 2013
16
Hi all-
I bought my current house as a foreclosure in 2012. The previous owner built a very nice pool complete with waterfall, slide, and grotto. However, he also incorporated some natural boulders (unknown what type of rock they are) as some accent points in a few spots around the pool and they are crumbling over time. So small chunks of rock crumble off into the pool, especially as the kids jump on them. We have lots of guests over so it is impossible to keep kids off them. In some spots the builder “covered” over them with what looks like a common material I see in other pools- the same stuff they build water features from- a thin 1” layer of concrete/mortar type material but in some spots it was never there. I’m wondering if there is a material I could buy and apply myself to cover and “seal” these rocks to keep them from continued crumbling. I live 75 miles from the nearest city and have an extremely difficult time getting any pool builders/companies to even ever come and give me a bid for any kind of work.
 

mguzzy

Well-known member
Jul 8, 2015
652
OV, CA
Can you send us a pic of your rock scape? Perhaps we can get a better idea if we can ID the Faux-cks
 

bdavis466

TFP Expert
Platinum Supporter
Aug 4, 2014
4,915
San Clemente, CA
The rock work is constructed of 3 parts washed plaster sand to one part plastic cement. One applied it's shaped, carved and painted to look like a real rock.

Yours looks like it's ready for a repaint
 

atropine

Member
Feb 4, 2013
16
Thanks! I did a search for plastic cement and found a product by that name at Home Depot that comes in 1 gallon jugs- looks like it is primarily designed for roofing. Does that sound like the same stuff?
 

bdavis466

TFP Expert
Platinum Supporter
Aug 4, 2014
4,915
San Clemente, CA
Thanks! I did a search for plastic cement and found a product by that name at Home Depot that comes in 1 gallon jugs- looks like it is primarily designed for roofing. Does that sound like the same stuff?
No that's not it. Home Depot sells Riverside Plastic Cement and Lowes sells Quickcrete Plastic Cement.

The paint is water-based exterior flat finish. Use a good primer made for concrete.

 

atropine

Member
Feb 4, 2013
16
Thanks! I’m gonna pick up some of the materials at Lowe’s and do a test run on another piece of similar rock that I have in the backyard. It looks like this is basically a “hard stucco” or a type of plaster product. I assume it will take a few days to dry?
 

atropine

Member
Feb 4, 2013
16
Thanks! I guess I am not too bright.... asking about if it is a type of plaster when the sand used in it is called “plaster sand”! Looking around online, some projects involving this kind of material have people adding a little “hydrated lime” to it to reduce shrinkage cracks and to improve “waterproofness”. Any validity to that?
 

bdavis466

TFP Expert
Platinum Supporter
Aug 4, 2014
4,915
San Clemente, CA
That's what plastic cement is - portland cement with lime and additives to prevent cracks and allow more working time.

I add different things depending on what I'm doing. I had thinset for added adhesion and fire clay when the surface is going to be exposed to heat. It all just depends on what you're doing but for normal uses the 3:1 mix is perfectly fine
 

atropine

Member
Feb 4, 2013
16
So both Lowe’s and Home Depot nearest me did not carry plastic cement. But Lowe’s had this other Type S mortar mix so I picked it up. I also grabbed a bottle of concrete binding agent. Would these work on? If not, I will drive across town next week to a different Lowe’s that does carry plastic cement I think.79FE3DE6-0AC9-43EB-8F9A-3D2E0C43E73B.jpeg
 

bdavis466

TFP Expert
Platinum Supporter
Aug 4, 2014
4,915
San Clemente, CA
Type S is basically a plaster mix so it should work for you.

There are some good rock carving videos on YouTube.... there are many more bad ones though. It's truly an art