Help!-Grinding Floor for Polyurea coating

[Offsidewolf]

Hi All,

After paying $7800.00 to have our 30 x 40 shop done professionally with polyaspartic coating, I've decided to tackle our new shop floor which is also a 30 x 40.

Cement was finished July 2018.
Rented a Husqvarna PG280 from a local dealer in Fargo ND.
What they had in stock for segments were the G644S, medium bond 30 grit.



Didn't do squat, I tried adding water, shutting the vacuum off, adding play sand to the surface, nothing worked.
Took the PG280 to an old cement pad and the grinder worked fine once it unglazed, back to the shop and glazed right back over.

Ordered the softest bond segments Husky had to offer. G1413S 20 grit, XS bond.
Started to grind and thought to myself I'm going to be done with this in 4-5 hours easy.

5 minutes later my smile turned into a frown, segments were once again glazed over. Same process, tried adding some water, sand, shutoff the vacuum.
So after 12 hours of grinding/polishing, not even one section is done, it's decision time.


Pay $2000 to have a pro grind the floor for me.
Or rent a shot blast from sunbelt?
Cost around $400 with shot, rounding up.
I don't want to throw good money after bad, but if you guys think a shot blast will work I could save $1600.
I guess if it doesnt work it'll cost us $2400

I think they only rent the small shot blast, I dont have the shop electricity set up to use anything larger anyway.

Any advice would be greatly appreciated.
Thanks!

 

[rnixon]

I did my 30x36 shop floor in May, concrete was poured in Sept 2017 and power troweled smooth and tight [ some areas slightly burnished ] I pressure washed it [twice] at 2500psi and that did open the pores to some degree, but since the polyurea was $210. a gal I wanted to make sure I got a good mechanical bond I used a full strength acid stain and it colored nicely confirming a porous surface ,but just to be sure after removing the residue of the acid stain and letting the floor dry for a week. in defiance of all recommendations. I did an etch with full strength muriatic acid, left it on for twenty minutes then neutralized twice. The result was a profile slightly rougher than 100 grit sandpaper , again let the floor dry for a week

The polyurea went down beautifully I could see it being absorbed into the concrete and bring the colors of the acid stain to life. I did the floor in one shot without assistance , took about 2.5 hrs. with an 18 inch 3/8 nap roller

It's been done less than 2 months but I've parked on it with hot tires, moved cabinets an floor jacks over it ,spilled gas an oil, dropped tools on it without effect , walked on it when it was covered with rust scale, then a quick wipe with a shop rag takes care of the grease an oil an a once over with a push broom and it looks new.

 

[LegacyIndustrial]

Pg280 is the red-headed step child of grinding. Rather have an Edco 10” or the Husky 450.

You need to add weight and try sprinkling a little water ahead of the machine. Can use a squirt bottle. This will cool the diamonds enough to keep them cutting.

Of course now you have a glaze so go to the area where you have already ground to cleanse them and expose the diamond grit again then go to the area that needs to be ground next, sprinkle the water and try again.


Sent from my iPhone using Garage Journal

 

[ctfortner]

Been there and done that, got the shirt! Here was my journey, which I never updated I see
https://www.garagejournal.com/forum/showthread.php?t=405772

I actually just finished my floor up 3 weeks ago after starting the process in late 2018. 4 grinder rentals, many diamonds, lots of hours and I got burned out with it. I already had the product also, just sitting in my bedroom, wife loved that. Long story short, I posted on FB groups, called and talked to local floor companies etc in hopes of finding someone to finish grinding mine hopefully on an off day, side job, etc...cheap is what i was after. It look many calls around, they reference another person and I would call them and so on. Finally found a local owner of an epoxy flooring place who was very friendly and willing to help. He said he would let his worker come do it for me on the side for $400 ($200 for the worker and $200 for owner to cover generator, diamond use, equip cost etc.) if I was able to wait on a slow day, so I did. That was a fraction of what most others wanted.

It wont look perfect if you have as hard of concrete as I did. Even the company said it would be no issue grinding, until they got there lol. He said this is the hardest concrete I have ever had to grind and they do 4-5 floors a week. But where it still had some dark grey "crust", it was very scratched and scuffed and he said your primer will stick to this no problem and so far so good.

 

[latuk]

Did you only put down one coat of the clear topcoat? What product did you use?

 

[ctfortner]

if you are asking me, yes I did one clear topcoat. I used the Nohr-S that Legacy above sells

 

[Armorpoxy]

Don't shot blast...in a novice's hands a shot blaster will leave 'lawnmower lines'....

A heavier Edco type grinder would work or hire a professional with a big grinder....

 

[Billwater24]

Most rental units ****. I have the Husq PG450 and it barely does the job. Check bigger concrete supply companies for rentals. It ***** because it’s expensive, but in the world of floor prep, it’s either done cheap or done right. You can always hand grind with a 7” grinder and a cup wheel. That ***** too, but it’s cheap and right. Hard work tho!

 

[Armorpoxy]

A good 7" grinder an cup wheel (and dust shroud with proper vac or Dust Deputy) can work, get knee pads and please wear a good particulate respirator.

We have had a few customers hire a 'local day laborer' for $150-$200 and let them do the work with the 7" hand grinder...problem solved. Just make sure you supervise!