Need help with surface prep

[Buck455]

I started down the path of epoxying my 30x32 shop floor. I have all the materials (with a few bumps along the way getting them), and I was all set to diamond grind the floor this weekend. I rented a floor machine and diamabrush yesterday, but it's hardly touching the surface. I have two year old concrete with fiberglass, and there are no surface contaminants or previous coating to remove. I have spent over 3 hours grinding the floor, and I have less than 100 square feet done. I'm pretty sure they have me the 25 grit disk, and there is plenty of material left. I just don't think I'm keeping the pace I see other people say they can do. I tried the machine out in my garage and it seems to work much better. So the question is, are there any other heads/machines out there that are more aggressive/effective? Or should I just pay someone at this point to do my 1000 square feet? I can't afford to spend 30 hours on this step.

 

[Shea]

Buck, do you have any pictures? Does the surface that you ground absorb water much better compared to what you didn't grind?

 

[LegacyIndustrial]

Buck:
Try adding some weight to the machine.

 

[jaye944]

I hired a diamond floor grinder from HD

and it was fantastic, it depends on the cutters, mine where new, there was no adjusting needed and no extra weight needed, you should not need to add weight.

The one I had didnt have a diamabrush, and possibly thats your problem.

I also had to sand down some epoxy filler,

You really want the ones with like about 16 cutters on the bottom. piece of piss using it, shouldnt take you more than an hour,

see my links I have pics

I started down the path of epoxying my 30x32 shop floor. I have all the materials (with a few bumps along the way getting them), and I was all set to diamond grind the floor this weekend. I rented a floor machine and diamabrush yesterday, but it's hardly touching the surface. I have two year old concrete with fiberglass, and there are no surface contaminants or previous coating to remove. I have spent over 3 hours grinding the floor, and I have less than 100 square feet done. I'm pretty sure they have me the 25 grit disk, and there is plenty of material left. I just don't think I'm keeping the pace I see other people say they can do. I tried the machine out in my garage and it seems to work much better. So the question is, are there any other heads/machines out there that are more aggressive/effective? Or should I just pay someone at this point to do my 1000 square feet? I can't afford to spend 30 hours on this step.

 

[Buck455]

Thanks Guys.

I added 50 then 100 lbs of lead to the top of the machine. It helped a little but, but not nearly as much as I needed.

I don't see a whole bunch of difference in water absorbtion between where I ground and where I didnt. The coloration is definitely different. My floor has a greenish tint to it, but turns normal white/grey where ground. I wasn't there when it was poured, but I don't think it has a sealer on it. Water seems to absorb, just very slowly. It doesn't necessarily bead up. It is very smooth though. I will attach a couple pics. You can see the color difference where I let the diamabrush work for about 20 seconds in one spot. The concrete is fiber reinforced and seems to be very hard. Acid etching didn't touch it after two applications, but it did make grinding a little bit easier where I tried.

I have a two row cup for angle grinder that definitely removes material quickly, but it's also very smooth. So the question is, what other tool could I use? Any ideas?

 

[CaConcreteCleaning]

Ive been a floor prep specialist since 1978 here, and when you run into fiber concrete its very hard to grind for prep. If your using a Dimabrush it means your not likely to be using a proper grinder for the job at hand. Not to offend anyone but a Diamabrush is more like a high end sanding paper. If you have a grinder you can use wet, thats your best bet for now. Wet will allow your tooling to get at the concrete better and give you a better chance.

Your bigger problem will be with the fiber showing through the coating. What happens is bits of the fiber will stick up and look like little hairs though your material. Its a big issue on goverment jobs which spec both fiber cement, and coatings. (think navy or airforce) One of the few things you can do once the prep is done is use fire to clean the floor. It will cause the fibers to burn off and give you a fighting chance. I suggest using a roofing torch for max ease and speed.

I hate to say, there is no easy answer with a fiber cement floor. They were designed to prevent the concrete from wearing out, and when your grinding it thats trying to wear the cap off the floor. Your in for a battle right now, no question about it. More weight might sound good but its likely to cause the tooling to overheat and glaze over loosing its cutting ability. A good set of soft bonded metal tooling on a proper grinder will go a long way. (like a sti or husqvarna machine)

 

[Notgrownup]

I hate to Hijack this but I have a question... I have fiber cement, been down only about 2 months now... I was thinking of sanding with a disk and a floor machine jus tto scuff but now that I see this post...Should I just etch and coat?

 

[CaConcreteCleaning]

I try to avoid acid as much as I can. I see a lot of floors that were poorly etched and the floor was not properly cleaned. (you have to put a strong base on the floor several times. aka baking soda, to make sure there is no more acid in the floor.) If you dont get all of the acid out it will continue to break down the lime in the cement and turn it into chalk in a few years. If able your always safer on the prep with a mechanical vs chem prep.

That being said... Fiber is a royal pain to deal with and your going to have a few things to work around. Wet sand and depending on what your putting down and the life cycle of the floor, and if your doing a low wear area like a garage you might get away with it. Dont forget to use some flame on the floor to clean off the fibers sticking up so they dont show through your floor. Always remember your prep is what your floor will look in the end. Bad prep and you see it in the final coat, no different then dry wall, paint wont hide a bad slab.

 

[Notgrownup]

I told my concrete guy not to float it to the point of holds, just smooth it out

 

[uniquecon]

Yeah we always burned off the fiber hairs with a propane torch and never had a problem. Pretty quick and easy. It will never be noticed again.
As for the fiber itself it does little to anything for strength. Most fiber used in residential and commercial is designed to be used for shrinkage cracks, so it adds little to know value after the first few days or weeks. With that most contractors don't add enough pounds per yard to be effective.

Ive been a floor prep specialist since 1978 here, and when you run into fiber concrete its very hard to grind for prep. If your using a Dimabrush it means your not likely to be using a proper grinder for the job at hand. Not to offend anyone but a Diamabrush is more like a high end sanding paper. If you have a grinder you can use wet, thats your best bet for now. Wet will allow your tooling to get at the concrete better and give you a better chance.

Your bigger problem will be with the fiber showing through the coating. What happens is bits of the fiber will stick up and look like little hairs though your material. Its a big issue on goverment jobs which spec both fiber cement, and coatings. (think navy or airforce) One of the few things you can do once the prep is done is use fire to clean the floor. It will cause the fibers to burn off and give you a fighting chance. I suggest using a roofing torch for max ease and speed.

I hate to say, there is no easy answer with a fiber cement floor. They were designed to prevent the concrete from wearing out, and when your grinding it thats trying to wear the cap off the floor. Your in for a battle right now, no question about it. More weight might sound good but its likely to cause the tooling to overheat and glaze over loosing its cutting ability. A good set of soft bonded metal tooling on a proper grinder will go a long way. (like a sti or husqvarna machine)

 

[Buck455]

I'm about shot on this project. I've tried a single row Husqvarana cup and now an Edco machine with super coarse stones at the suggesting of my local industrial rental company. I'm just not making any progress. Any body have any other ideas. Is acid etching a better solution at this point? if so, which product?
Thanks for the feedback thus far guys.

 

[LegacyIndustrial]

In an inconspicuous corner.

Mix 4 or 5 different strength batches in a dixie cup or similar.

Start 6:1 (water to muriatic), then on down the line.
Most floors react pretty well to 5:1, yours might be different.

Once you find a batch that reacts well, good quick fizz, go from there.
Be careful, wear the proper PPE.

 

[shaun oriold1]

You can see about renting a shot blaster? Not sure if they're available for rent... You would need to do a light grinding afterwards to get rid of the corn rows though.

Shaun

 

[LegacyIndustrial]

Good point by Shaun.
A shot-blaster should be your first choice before the etch.
It should be able to overcome the difficulty you are having with this surface.