Hi Folks I am building a sculpture and would like to try and use GFRC,and I need to build up the coats over a few days so I will not be able to finish the three coats all at the same time will i need to use an adhesive like thistlebond of a pva adhesive between coat to avoid delamination or is it impossible to achieve ,i will be vertically sculpting the piece any help would be gratefully received in will be an outdoor piece

Darby

Views: 344

Reply to This

Replies to This Discussion

I'm not sure what you are building, how it will be used or how thick each coat needs to be, but I have done a lot of overlays on horizontal and vertical surfaces using commercial overlay products like Elite crete or Concrete Coatings Inc.    It's not gfrc.

The secret to a good bond is acid etching or grinding the surface to open up the pores which gives the acrylic bonding agent something to grab.  Just painting the surface with acryl 60 will not work well.  The acrylic needs to be in the mix.  The concrete needs to be fully cured before applying an overlay.  Perhaps a vertical carving mix would be more appropriate. 

If you don't have commercial overlay products available here's a freaky tip.   Make your own.  50/50 white portland and silica sand mixed with ELMERS glue.   Ok, I've never done this but others have.  Test first.   There might be an actual recipe on the gallon bottle of Elmers glue to make concrete admix.   Not sure.  Try Use 300mL adhesive and 150mL water combined per ten pounds of concrete mix. add more water if required.  I'd mix the glue with the water first and spray a coat on the cured surface first.

No kidding about the ELMERS - http://elmers.com/product/detail/E862

Apparently ELEMERS started making a product specifically for this.  Back in the Day, they didn't make this.

Keep it wet using a spray bottle of glue water mix, it dries fast.

Thanks Dave much appreciated,we would not have Elemers in Ireland I would think. I never saw it any were but we do have a similar product called thistlebond which I have  used a lot in my construction days and which is a good product.it has sand in the mix as well.

This is a 4 ft square sculpture carved out of polystyrene  by the artist and she wants to coat the form in coloured concrete, it is for outdoor display.I was considering GFRC because of its strength and density but I would also consider using a vertical carving mix but I found it difficult to find a definitive mix formula you don't have one by chance? From what I can gather it is similar to a std mortar mix of 3 to 1 cement and maybe use kiln dried silica sand instead of std builders sand.without super P which would only make it want to fall of the vertical surface Id imagine when trying to apply it.I was  imagining  something like Buddy Rhodes  press  clay like mix.This is completely new territory for me so any help is really welcome    

Dave McVey said:

I'm not sure what you are building, how it will be used or how thick each coat needs to be, but I have done a lot of overlays on horizontal and vertical surfaces using commercial overlay products like Elite crete or Concrete Coatings Inc.    It's not gfrc.

The secret to a good bond is acid etching or grinding the surface to open up the pores which gives the acrylic bonding agent something to grab.  Just painting the surface with acryl 60 will not work well.  The acrylic needs to be in the mix.  The concrete needs to be fully cured before applying an overlay.  Perhaps a vertical carving mix would be more appropriate. 

If you don't have commercial overlay products available here's a freaky tip.   Make your own.  50/50 white portland and silica sand mixed with ELMERS glue.   Ok, I've never done this but others have.  Test first.   There might be an actual recipe on the gallon bottle of Elmers glue to make concrete admix.   Not sure.  Try Use 300mL adhesive and 150mL water combined per ten pounds of concrete mix. add more water if required.  I'd mix the glue with the water first and spray a coat on the cured surface first.

Yes Matthew I was thinking that as well because I will be working with people who have no experience in concrete work so its important to get a definite plan together and be confident in the procedure, I have used thistlebond before here in Ireland and its a great product similar to the acrylic 60 id imagine it would work between gfrc coats as well once the subcoat was keyed,,and maybe the gfrc is over the top and as Dave says a vertical sculpting mix might be more appropriate.   

Matthew Burke said:

id use bonding agent acryl 60. or other similar product. maybe dilute a bit 50/50, brush it on almost like you apply a primer for a self leveling underlayment. way back i was tiling and decided to use a self leveling underlayment over concrete without using the POLYMER primer. it did not adhere and curled up and broke into pieces-worthless. another lesson hard learned

same goes for the FC and BC you may need to use acyrl 60 to make sure it bonds correctly if FC gets too stiff before backer. why take the chance?

Kind of confused now.  Your just coating foam?   That sounds like stucco.  http://www.stuccoguru.com/resources/article.cfm?articleID=A-01050&a...

This is the sculpture Dave as you can see the circle base and the "fountain seat" are in concrete very experimental. We are going to use nano pigments to get the colours as vivid as possible.My thinking is that if it  is done in gfrc it will have strength and density and will be structurally independent. The polymer will also eliminate any chance of cracking or weakness in the gfrc mix.the only problem using gfrc is the small window that you have to sculpt the piece I was going to build up about 3 coats of backing coat sculpt the basic form and this is the crunch question. can I come back the next day and add the face coat with the colours and somehow avoid delamination by using acryrl 60 or our equivalent here?    

I think you can build up 3 coats of mix using the acyrl 60.   Keep a spray bottle of acyrl 60 diluted with water to keep a wet edge.

Thank Dave much appreciated 

Dave McVey said:

I think you can build up 3 coats of mix using the acyrl 60.   Keep a spray bottle of acyrl 60 diluted with water to keep a wet edge.

Reply to Discussion

RSS

Sponsor's Training

Concrete Countertop Mix Recipes

Featured Product

    Featured Product of the Month

Fishstone's Super-SIX-Admix™ is a proprietary blend of SIX different admixtures designed to achieve pinhole free, dense and strong concrete that will free flow in precast molds.  Super SIX makes it easy to produce Ultra high performance concrete (UHPC), also known as Engineered Concrete Composition (ECC) and Reactive Powder Concrete (RPC).  Super-SIX™  is a non-hazardous material utilizing the newest and most advanced technologies.

© 2018   Created by Tom Fischer.   Powered by

Badges  |  Report an Issue  |  Terms of Service