# GFRC Concrete Countertops



## 1acre

_Introduction_
Concrete countertops are all the craze these days. With products like "z counterform" coming into place, many opt to pour in place. But nothing will ever replace the ability to make a piece and place it onto your cabinets. Or you could make a coffee table. Or you could make that trendy waterfall edge. Cast in sink? All things pouring in place makes much more difficult, and practically *impossible* for the avg joe. 

The good news is it is rather easy to make a quality piece. The bad news is information is rather limited. While I fall more into the "hack" category, I thought it would be beneficial for at least me to document all I have compiled and learned about concrete countertops and why GFRC is the bees knees. This way, at least I can repeat what I have accomplished thus far. 








My 2nd ever concrete countertop, cast in sink with a mold I made myself

_Why GFRC???_
GFRC stand for "*G*lass *F*iber *R*einforced *C*oncrete." The advantages are:

casting pieces with glass like finish and no filling in vugs with grout
extremely strong, what used to have to be 2" for a cast piece can now be 1" or 3/4"! 

Like everything else in this world, the process comes with some drawbacks. Namely the cost of the tools. Those without access to a nice compressor could find the process cost prohibitive. I run a 60 gal compressor on 240v. They make specialized guns to spray the mix, but I used a good ol' harbor freight drywall texture gun with a few low cost mods. The mix can be pricey if you plan to shoot just a small piece, but you can always go the Buddy Rhode. Pun intended. Or some other outfit such as fishstone, trinic etc. 

One lesson I've learned the hard way in the DIY world is one of the end goals is to save money (at least for me, I just bought all the fixtures/toilet/tub for my master bath at the tune of $11k!). But saving money doesn't manifest itself as buying everything for the lowest price. It is saved by not having people charging $100/hr (which is what everyone wants in my area) plugging away at your project. So spend some money to make the job go easier. You'll save money, you'll build something yourself and the wife won't bust your balls as much. I know women do DIY stuff, and as the father of 3 girls, I really just wanted to say "bust your balls." 

_General Resources_
GFRC Primer from concrete countertop institute





_Tools Needed_

Air compressor capable of running a drywall texture gun. considering renting. 16 CFM gas compressors rent for about $70/day in my area.
drywall texture gun. I use the harbor freight version w/ a fernco to a 45 pvc. Problem is I had to epoxy in the hopper to the pvc fitting since the hopper is a different size than any pvc fitting I could find. Or, as I am about to do, bite the bullet for ~$100 and get the Kraft PC401. 
 chip brushes
 caulking balls. giggity. many concrete countertop supply houses sell these for $30+ a set. You can buy the same thing for ~$7 on amazon if you search for fondant tools. Some people cut wood dowel at 45 degrees, but I find that to be much more difficult.
table saw is handy for cutting up melamine. A circular saw with a guide (another piece of melamine clamped down) is how I do my big cross cuts since setting up for that is a PITA in my shop.
wet grinder with diamond pads. Can be had ~$100 on amazon for the grinder, another ~$30 for the pads. 
scales. seriously, you need a good scale. See concrete countertop institute's blog post on scales. I bought some adam's scales on ebay as they seemed to be the best bang for the buck. 
fiberglass roller
beakers, containers (my family eats a lot of cottage cheese for some reason:vs_worry, and syringes help for the smaller volumes 
 buckets. 5 minimum.
 mortar mixer (I used to use a cheap hammer drill from harbor freight and then I graduated to harbor freight's mortar mixer).
bandsaw and router table are helpful for cutting sink templates, but not needed. 
a helper is...well, helpful. sometimes. 

_Materials_beside concrete and admix

melamine
templating material, I use the thinnest sheet material I can get my hands on.
caulk. if your melamine is white, get a dark color caulk. I used black, but you want a lighter shade so you can see anomalies in your caulk job. 
 mold wax
1" pvc
polystyrene foam (the "pink panther" insulating stuff at the big box store)
 AR scrim
sealer. I've used the stuff you buy at the big box store for natural stone and it is about $100 for a gal. On the picture above I used U-seal from fishstone.

_The Mix_
As mentioned earlier you can simply buy bagged stuff from people like fishstone, trinic, buddy rhodes and I think Cheng now sells it. I would urge caution and steer clear from the quikcrete "Countertop mix" sold at the big box stores. I spent some time searching about 18 months ago, and I could never really understand what was in that bag. 

GFRC also varies from typical concrete mix in that there is no aggregate. NO AGGREGATE. No pebbles, no rock, no unsieved sand. GFRC has 2 mixes, the mist coat that is sprayed on and the backer coat which is lumped in, usually by hand. They both have essentially the same ingredients with the exception of the glass fibers. 

My google sheet calculates what is needed for the mix I use. Use at your own peril. But, it is based on fishstone's mix. 

Below is what I sourced and where:

Portland - White type I. Lehigh and Federal. I prefer the Lehigh. I source at a local supplier.
White sand. WHITE. and washed. As someone who will buy close to 500 million lbs of sand this year, it is expensive in the little 50 lbs sacks. I get it with my portland. 
Poz. Vitro Minerals VCAS only. I used to buy by the sack from expressions ltd (it seems they only sell by the pallet now), but you'll need to shop around to see who has the cheapest price with shipping. If you're like me and have a Reynold's in your town, they carry it. 
Acrylic Polymer - Forton VF-774 only. Period. Maybe not, venture out with the stuff from the big box store and report back how it worked out. I sourced from Reynolds Advanced Materials as listed above. 
AR glass fibers. I source from reynolds. Trinic, expressions, fishstone, buddy, cheng all sell them. 
Plasticizer. I used Optimum 380 from fishstone. 
Defoamer. I used C-64 from fishstone.


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## 1acre

Saving for future rants


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## 1acre

Saving space???


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## 1acre

last one


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## LanterDan

Thanks for posting this. I've given serious thought to trying this in the past and may again soon. Several questions if I may:

1) Do you know if there are shelf life constraints on the mix ingredients? It seems that many of them are only available to larger quantities (VF-774 seems to only be available in 5 gal pails for example). I assume the pozzolans would decay with humidity like cement? What about the polymers and plasticizers? 

2) It seems like of these things you have to buy online/mail order. You mention Reynolds for the polymer, but there isn't one near me. Anyone know any other place to try to source some of this locally and avoid shipping? I'd think about the bag mixes you mention, but paying shipping on concrete seems dumb. GFRC seems very popular right now, so I keep thinking there has to be a place to buy this locally, but I don't know where.

3) I'm thinking about trying something like Buddy Rhodes GRFC powdered admix (supply your own cement/sand and plastizer). Anybody tried this? Somewhere I read its a little harder to work with compared to a "from scratch" recipe. I've read this and this which suggest it can be used effectively.

3) Do you make your own sink molds? Do you do any that are curved? 

4) Please tell me you aren't buying 500 millions lbs of sand just for gfrc mixes. I hear it can be addictive, but that is a lot.


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## 1acre

1) Seems 1 yr is the number. I called fishstone (who is very friendly and helpful btw) and they recommended 1 yr. It makes it tough for diyers who are just making small projects, but probably still cheaper than paying someone to do it. So, yes to all...poz and chems.

2) again, I would recommend fishstone. It sucks to have to mail order it, but they get it and will help to minimize the damage. 

3) I don't like dry ads. In my joe job, I flush chems, water and sand into the ground and dry ads are like the number one no-no. Batch mixing it isn't so bad. But, even when adding coloring one should mix the color into solution and then dose. It allows better control. The short answer is, the admix probably gets the job done, but having control over everything is best. 

4) Yes, I made my own sink mold from mdf and polyester resin. Depending on the shape, you may have to switch to polystyrene and epoxy. I found this article helpful. You can also buy sink molds from expressions. 

5) Last year I was buying northern white for around $0.03/lb. This year it's going for about $0.07/lb. In the sack is a lot more!


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## LanterDan

Thanks. That was the answer I was expecting on shelf life, but I'm still disappointed. Not only is there the expense of buying more than I need, but there is the hassle of disposing of it. 

I may do it anyway, or I may give the admix a try. Or I may stay with convention pre-cast I've done before. Or I may go corian. I keep going in circles.

I liked the mold article.


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