Concrete garage floor grinding question?

[noyu]

Hi,

I tried the search function but can't seems to find what I need to know and I am just about to start work on the garage floor and can't seems to find the "shot blaster" from several of my local tools rental places.

The only machine I can find is a Edco floor grinder but they only offer 10 grits grinding stone and not diamond grinding stone.

My questions is how hard it is to grind 400 s.f. with 10 grits grinding stone?

The cost of the rental on machine is $100 / day plus I have to buy the stones at $10 each and I need six for the dual Edco grinder.

Anybody knows how long or roughly how many sets of stone I need to grind a 400 s.f. garage?

The concrete floor is about 4 years old with no coating or sealer on it and the condition is not bad without many high spots except several hairline cracks which I will be filling it with epoxy crack filler prior to apply epoxy coating.

Also, can I just wash / degrease the floor and repair cracks with epoxy and grind the repair along when grinding the surface?

Do I still need to etch the floor after grinding?

Sorry for the long post because this is my first real epoxy make over project and really need some help / advise here.

Thank you in advance!

 

[mhoffm911]

My local Home Depot has a new machine that rents for cheaper than that. Downside is you have to buy the grinding wheels, thus bumping the price up.

I'll let the others chime in on your other questions.

For what it's worth, my thoughts are that I would do the following:

1. Powerwash the floor
2. Clean with Simple Green & rinse
3. Use Cascade or Tide to try and get the stains out & rinse
4. Epoxy patch the cracks
5. Acid etch & rinse (may need to do a couple of times)
6. Powerwash & rinse
7. Put down the epoxy & enjoy

 

[noyu]

My local Home Depot has a new machine that rents for cheaper than that. Downside is you have to buy the grinding wheels, thus bumping the price up.

I'll let the others chime in on your other questions.

For what it's worth, my thoughts are that I would do the following:

1. Powerwash the floor
2. Clean with Simple Green & rinse
3. Use Cascade or Tide to try and get the stains out & rinse
4. Epoxy patch the cracks
5. Acid etch & rinse (may need to do a couple of times)
6. Powerwash & rinse
7. Put down the epoxy & enjoy

mhoffm911,

Thanks for your reply!

That's what I was thinking to do if I abandon the grinding option.

However, this is what makes me hesitate: I lived in Toronto, Canada and the winter gets pretty nasty (snow, slush, road salt etc) so I was hoping with shot blasting (which is not an option anymore cause I can't seems to find one available) or surface grinding can make the epoxy adhere better and will last longer (hopefully many years).

If I prep the floor properly like what you suggested do you think I have any problems due to the climate that I am at.

Also, should I repair the cracks after the etching because I am concerning about the acid with degrades the epoxy crack filler?

Thanks for any suggestions and advice I really appreciated!

 

[rt66jt]

There are diamond wheels available for the Edco floor grinder, and that is what you want. Check with a local construction supply house, preferably one that specializes in concrete and masonry products. They may rent the equipment, or know who does. Almost any concrete guy will tell you to keep acid away from concrete. Acid dissolves and weakens concrete, that is why masons use acid to clean up their "oops."

 

[noyu]

There are diamond wheels available for the Edco floor grinder, and that is what you want. Check with a local construction supply house, preferably one that specializes in concrete and masonry products. They may rent the equipment, or know who does. Almost any concrete guy will tell you to keep acid away from concrete. Acid dissolves and weakens concrete, that is why masons use acid to clean up their "oops."

Thanks for your post!

The guy at the rental place told me there are different grids stone for grinder and does it apply to diamond wheels?

Any tips or advise will be very much appreciated!

 

[FL_Javelin]

I had to grind my floor since I couldnt use acid with a metal building. I used HD, $120/24hrs I think. It was a fairly course blade. My garage is 750sf, took us all day. As good a job as my concrete contractor did, there are still imperfections that the grinder will leave, lower areas in the concrete

I would just hit these areas with a hand grinder. See my link below for more details

Wife taking over grinding for a bit. I had to take it away from here when she was not sweeping it and making low spots!

 

[noyu]

I had to grind my floor since I couldnt use acid with a metal building. I used HD, $120/24hrs I think. It was a fairly course blade. My garage is 750sf, took us all day. As good a job as my concrete contractor did, there are still imperfections that the grinder will leave, lower areas in the concrete

I would just hit these areas with a hand grinder. See my link below for more details

Wife taking over grinding for a bit. I had to take it away from here when she was not sweeping it and making low spots!

Thanks for your post!

Do you mind if I ask you what kind of grinding wheel did you use?

Are they grinding stone or diamond wheels?And if grinding stones how many sets of stone did you went thru before you can finish your garage?

Thanks again!

 

[rt66jt]

For diamonds, there won't really be any choice of "grit." A diamond wheel should last your entire job.

 

[FL_Javelin]

For diamonds, there won't really be any choice of "grit." A diamond wheel should last your entire job.

This is what I had I believe. No choice was given at HD and it worked as good from beginning to end.

 

[dds4]

I'm in the middle of epoxying my garage and just finished the floor grinding part.

Here's my take, feel free to correct me if I'm wrong.

Shot blasting: the best but not practical in most homes. Usually reserved for much larger projects like factories/shops with a larger surface area. A rather large machine is used to blast the floor with mini ball bearings.

Stand up floor grinders: Next best, but the rental fees I've gathered are twice as much as hand grinders. Around $150+/day for rental not including the grinding wheel attachment.

Hand grinder: About 10-12 inches in diameter, you have to get on your hands and knees. Pain in the ****. $50/day from Home Depot not including the grinding wheel attachment.

Attachments are at least $50 for a decent one and you might go through 2-3 attachments depending on how much you grind.