additive for cement

[biggunn]

I am wondering if anyone knows of, or can recommend, an additive to use with anchoring cement to make it less brittle. we make sculptures and one part of them are prone to breaking. We used to use a product called pour-stone, which worked great, but the company stopped making it and does not have a replacement product for it. We are currently using a two part plastic to make the part, but it is expensive and more difficult to use, along with some other issues. We would really like to get back to using a cement to do it with, but all of the ones we have tried are brittle and have a tendency to chip, if not break.

Does any one have any experience using something like a Bone Emulsion, a polymer, or rubber powder to add to cement to give it just a little bit of give and to make it less brittle?

 

[clonesix]

rebar

In general, gypsum does not survive tension forces and must be reinforced, or pre-tensioned.

For better information than can be acquired on a modeling board, try contacting U.S.Gypsum.com

 

[biggunn]

We do reinforce it, not with rebar, but with 16 penny nails. Rebar would be too big for our purposes. More of the issue is the brittleness and chipping. We have talked with USG, and do use and/or have tried several of their products, such as hydrostone, but the issue remains.

It just seems that there has to be something that could be added to the cement to give it an ever so slight amount of resilience.

 

[stigmorgan]

Have you tried pva glue? You might have to experiment with the ratios to get what you want but may be worth a try as it does dry like a flexible plastic.

 

[biggunn]

Haven't tried it , but I can. I think I have some on a shelf somewhere.

 

[8 perf]

Have you tried dental stone?

 

[biggunn]

I haven't. Actually havent heard of it, but I will take a look.

 

[vistaVision]

Check with the folks at Smooth On. They have some glass fiber and acrylic polymer additives for cement/concrete reinforcement that might be of use.
https://www.smooth-on.com/product-line/forton-vf-774/
https://www.smooth-on.com/tutorials/gfrc-explained-learn-basics-gfrc/

 

[biggunn]

That Forton VF774 sounds like just what we are looking for. I will have to look into it a little more deeply. Thanks for that.

 

[Zinger]

Have you looked at glass fiber reinforced concrete? It's used to make concrete counter tops and architectural pieces. It might hold up to your application.

http://www.concretecountertopinstitute.com/introduction-to-gfrc-glass-fiber-reinforced-concrete/

 

[biggunn]

I only looked at GFRC today following vistaVisions links. It actually wont work for what we are doing as we need to be able to pour it into a mold.

I did find another product today: http://www.thoroproducts.com/pdf_info/Acryl_60_sellSheet.pdf . Not sure if it will work yet, but it is less expensive than the Forton VF774 and it is available locally.

 

[Predatoj]

In the States they add a finite amount of dental plaster to ultracal 30, about a cup full to one batch. You can't mold in full dental stone because it warps too much it just acts as a strengthening agent. Other than that burlap strips.