Hi, My name is Marc, from Barcelona(spain), first, greetings to all Members, second to apologize because my English is not very good, I hope you can understand my words.

I'm doing pieces in GRFC with the Brandon Gore formula, initially had problems with bubbles but practicing with my hopper gun I got no more bubbles and holes, but I have a problem and I do not know how to solve, are micro cracks, I am using the formula and all similar products, the only product is different, I use cement portland cement TypeI CEMEX, and puzzolans metakaolin of powerpozz because V-cas for vitrominerals not distribute in Europe. Also say that in my land now the temperature is 40ºC during the day, can you help?.

Thank you very much from Barcelona, Spain.

Marc

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Marc,

It's obviously hot where you are. I'm thinking your spray coat is setting up before you get the back coats on. You need to add the SCC or scratch coats as soon as your face coat starts to set. You'll see it start to change from shiny to dull , that's the right time. Not before or it could push the fibers through. If you wait too long, that's when the micro cracking happens. Make sure you have all your batches ready before starting so timing won't be an issue.

I'm in Canada, and had the same thing start to happen as soon as we got our annual 2 weeks of hot weather. No problems since.

Hope that helps.

Brian
Hi Brian, thanks for your speedy response, tonight I will work in my workshop after 22h, since lower the temperature considerably, the technician where I buy the cement tells me which may also be that the cement I use is very powerful then the cement "pull" too hard and may crack, I understand what you tell me and I'll do so.

Now I am using Type I cement 52.5, I will lower the power of the cement and will use 42.5.

Sorry but I don't know some names and their abbreviations, which means SCC?

Today in my work 42ºC !!!!!!.

Thank you very much/ Muchas Gracias.

Marc.

Brian Webster said:
Marc,

It's obviously hot where you are. I'm thinking your spray coat is setting up before you get the back coats on. You need to add the SCC or scratch coats as soon as your face coat starts to set. You'll see it start to change from shiny to dull , that's the right time. Not before or it could push the fibers through. If you wait too long, that's when the micro cracking happens. Make sure you have all your batches ready before starting so timing won't be an issue.

I'm in Canada, and had the same thing start to happen as soon as we got our annual 2 weeks of hot weather. No problems since.

Hope that helps.

Brian
Hi Marc,

SCC is "self consolidating concrete". I'm not familiar with what what CEMEX will do to your mix, but switching to a regular Type 1 will eliminate that question.

Brian
Marc,

It could also be because your mist coat is too thick and what your seeing is shrinkage cracks. I spray PVA (8mm) fibers in my mist coat. They spray fine and reduce/eliminate shrinkage cracks.

Tom
Thank you Tom, But, I don't know that is PVA (8mm), Can you explain to me? A bit simple for me?.

Fiber in the face coat?

I ask a little patience with me, I'm new to the GFRC, my English is not very good, and here in Spain there is no culture of "concrete" like in EEUU.

PD- Tom, I'm seeing your website, I knew it, great page, I see now that are PVA fibers, I try to understand, but their application and use I don't how it works.


Marc.


Tom Fischer- Fishstone,CCS said:
Marc,
It could also be because your mist coat is too thick and what your seeing is shrinkage cracks. I spray PVA (8mm) fibers in my mist coat. They spray fine and reduce/eliminate shrinkage cracks.
Tom
Marc,

Basically you may want to use a small micro fiber that you are not able to see in the face/mist coat. A PVA fiber is the best to use because it has a chemical bond to the cement and actually adds some structural support to the concrete. However if all you can find is Nylon or Polypropylene these will help also with shrinkage cracks. Keep in mind that you still need to use the AR glass fibers for the back coat.

Hope this helps?

Tom
Tom

Thank's, I've been watching your website, I have sought information and I think I find the fiber fiber in distributors here in my area. Soon, if you do not mind, I will send you a message.

Thank you very much.
Alla.

The Grace commercial in spain visited to me a few days ago, gave me samples of the Adva Cast 555 and told me to test samples not hesitate to ask, I let explain what shrinkage reducer. The BASF comercial visit to me the next week in my workshop.

What thickness has to have the face coat? what texture is optimal for the mix (face coat)? like a milkshake? like yogurt?

when I tipping the mix in the hopper gun that has to flow only?


Right now the heat problem is that the face coat is dried on a non-uniform and is difficult to find the timing for apply the SCC as there are areas which dry very quickly above all the edges.

Today 43ºC........ That makes it difficult to work ................I will.

Thank you all.......

Marc.
ok, friends, I talked with Grace comercial in Spain and he will send me a sample Eclipse floor, my question is, according to the formula I use, I will have to change this formula? reduce the water in terms of amount shrinkage reducer?


how many questions right? I hope not be tedious.


Marc.
Marc,

I'm by no means an expert, but before you go out and add a bunch of new chemicals to your mix, talk to your polymer manufacturer first. They can be a great resource on problems like this. If it's Forton VF774, they recommend against using any additional shrinkage reducer, as this is one of the primary benefits of using a polymer in the first place.Here's a link to some info on Forton that might help.

http://www.ball-consulting-ltd.com/site_content/documents/why%20use...



Also, one other suggestion for your face coat in hot weather, make sure your water is chilled. It will make a big difference in setup time.

Good luck.

Brian

Marc said:
ok, friends, I talked with Grace comercial in Spain and he will send me a sample Eclipse floor, my question is, according to the formula I use, I will have to change this formula? reduce the water in terms of amount shrinkage reducer?


how many questions right? I hope not be tedious.


Marc.
Brian

Yes, I am using Forton VF-774, but in Europe it is marketed under another name, Dyflex LP9908, cement, sand, Forton, Liquefaction compound by Goredesign and powerpozz of metakaolin, so far I have tested with dye powder, but today I going make test a liquid dye "mixol" by Fakolith, they have some very powerful and bright colors. First I'll prove mix to coat the face a little wet as I think was far too dry, I'll apply the SCC of the way I suggest the comrades of the forum, I have doubts of as has to be the thickness of the face coat. ......

thank you.

Marc.
Alla.

use Eclipse with the Forton? The same formula + Eclipse?.

I made several tests with the formula that I using, I apply the SCC at the time that you told me, and all tests are perfect, without micro-cracking, but I have seen that if there are micro-holes (needle head) I guess that's because I use too much air?.

On the other hand, when I don't use pigments and use only gray cement in the piece exist different shades of color, is normal?.

Thank you.

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