Two concrete grinding questions....

[BRENT in 10-uh-C]

1) I am using an Edco 22" diamond blade grinder however it only grinds up to about 3" away from the wall. What do I need to use to grind the concrete up to the wall?

2) The floor I am grinding was sealed many years ago and I am prepping for installing an epoxy primer. How much grinding do I need to do? Looking at the pictures below, is an occasional swirl still showing OK, or does it need to be perfectly ground!

 

[Shea]

You can pick up a 4" angle grinder from Harbor Freight for $15. The concrete turbo cup wheel that you will need for it is $30. This setup works great for getting the edges and other small areas. Just be prepared for the dust and be sure to where a mask.

The occasional swirl mark is fine as long as it's not a gouge or groove. Make sure to do a water drop test in areas to verify the coating is completely removed. If the water absorbs quickly you are good.

 

[SunsetsAndFriends]

1) I am using an Edco 22" diamond blade grinder however it only grinds up to about 3" away from the wall. What do I need to use to grind the concrete up to the wall?

2) The floor I am grinding was sealed many years ago and I am prepping for installing an epoxy primer. How much grinding do I need to do? Looking at the pictures below, is an occasional swirl still showing OK, or does it need to be perfectly ground!

Remember that anything that you see on your floor now before coating might show through the coating. So, fix any imperfections that do not want to chance showing through. Keep in mind that 20 mils is just a little under 1/64 of an inch. So even 20 mils is not going to hide much. By the way 20 mils is 100% solids epoxy applied at 80 sq ft per gallon.

As for the 3" next to your walls, I recommend a Bosch CSG15 5-Inch Concrete Surface Grinder. I purchased this for $399 on Amazon because renting this would cost me $80 per day at my local rental store. I'm so glad I purchased instead of renting. It took me 2.5 days of grinding to finish my garage/shop floor. And so I own this tool and can finish the remainder of my basement this summer. Had I rented it, I would have lost money.

This Bosch grinder is amazing. Virtually dust free. And it works quickly. This is what I would recommend. Not to mention that since the diamond wheels last, last, and last, you could probably sell this tool after your project and end up spending less than you would have by renting.

My 2 cents. Hope it gives you a helpful perspective and good luck.

 

[wagspe208]

I'd go just a little more. I did, I know it is tedious as ****. But, if using a good epoxy, you won't remember the hours of grinding the day after the paint is down.
Wags

 

[BRENT in 10-uh-C]

Ok, now that the floor has been ground, and vacuumed, how do I get the remaining dust up? I have read about using alcohol & a lint-free towel, but the area is about 3000 sq ft. I am not sure there is enough alcohol in the county ( --both drinking & denatured! ) to get all the dust removed!! FWIW, there is dust on everything from light fixtures to perlins on down to the floor. Thoughts??

 

[sammons]

when I prepped mine, i used the standard 4" Dewalt grinder with the diamond cup wheel and it was more than adequate. i however did use a shot blaster instead of the grinder for the rest of the floor.
i made an attachment to go over the grinder to hook up to the concrete vac.

after grinding i swept the entire floor with the vac a few times, then used a leaf blower, hand swept, and vacuumed again. it was very tedious and i thought it would never end. then i treated the area as if it was a clean room prior to putting the primer coat on.

you could always hose it out, but ensure you thoroughly let it dry before coating, or so i have read.

 

[LegacyIndustrial]

Broom and blow the heck out of it. You can wipe with a good cloth, damp with denatured alcohol.

And as my friend from the great state of Tennessee mentioned in another post, watch out for rags washed at home, the laundry soap residue can mess up the surface.


Sent from my iPhone using Tapatalk

 

[Armorpoxy]

Agree, an inexpensive hand grinder for edges works great.

 

[wagspe208]

There are "edge grinders" that get right up to the edge of the wall.
Vacuum, brush, vacuum.
The denatured alcohol... wtf is overkill if the floor was clean to begin with (before grinding).
One dude that told you what he did has a thread where he does not have a floor that is right. It is blistered... but he is an engineer so it is not his fault, someone else's.
Wags

 

[rburke65]

What is the issue with "rags washed at home"? Should I take mine to a neighbors house or what?

 

[BRENT in 10-uh-C]

I have had two people vacuuming every day for a week and we still have dust. Since last Friday, we have been running 3' fans with filters on them which has helped some too, ...so my next question is what happens if I were to use my steam cleaner to wash out the floor. If I were to keep the heat & fans running to dry out the concrete, would this be a bad thing?

 

[Shea]

No, not at all. As long as the concrete has dried out completely and isn't still emitting moisture from drying out you will be fine. Before you go through all that though, have you tried wiping down a section of floor with denatured alcohol? Apply it liberally to a clean rag and wipe down a section of the floor to test. This usually works well for excess concrete dust.

 

[BRENT in 10-uh-C]

No, not at all. As long as the concrete has dried out completely and isn't still emitting moisture from drying out you will be fine. Before you go through all that though, have you tried wiping down a section of floor with denatured alcohol? Apply it liberally to a clean rag and wipe down a section of the floor to test. This usually works well for excess concrete dust.

The floor size is about 3,000 sq. feet, so I am hesitant to order a 55 gallon drum of alcohol and a pallet load of towels!

 

[Shea]

The floor size is about 3,000 sq. feet, so I am hesitant to order a 55 gallon drum of alcohol and a pallet load of towels!

Yeah, that makes sense....

 

[mopar440_6]

I'll be doing the same thing in my 3000 sq. ft. shop as soon as the order arrives. My plan for cleaning is vacuum, leaf blower, vacuum, leaf blower, vacuum, then denatured alcohol and a couple of Swiffers with the WetJet pads. My only concern is how much of the other kind of alcohol I'll have to supply to my friends to get this accomplished.

 

[LegacyIndustrial]

99% of the floors we do get 3 good sweeps, 3 good runs with the electric leaf blower, 5 -10 mins per run, size dependent.
Rarely do we wipe the floor.

 

[tncatadjuster]

99% of the floors we do get 3 good sweeps, 3 good runs with the electric leaf blower, 5 -10 mins per run, size dependent.
Rarely do we wipe the floor.

Blow or vac only required, where does all this wiping come from?

 

[BRENT in 10-uh-C]

Just a quick update. Used the pressure washer with 150 degree heat, and a broom with a small amount of Dawn soap (barely enough to see suds) over the entire floor yesterday morning. There was brown water everywhere as we broomed and pushed the water out the door. Repeated the process after lunch without the soap. Left the furnace on 75 degrees last night along with a fan blowing around. Water all gone this morning. Planning on vacuuming this evening one more time after the dust settles, and start applying the epoxy primer in the morning.

Very likely I am being too **** about this clean-up, but I am paranoid about adhesion issues.

 

[Gerald O]

I wouldn't start with the coating so soon after washing with water. It may appear dry but likely still has moisture below the surface. Give it plenty of time to dry and do a moisture test.

 

[tncatadjuster]

I wouldn't start with the coating so soon after washing with water. It may appear dry but likely still has moisture below the surface. Give it plenty of time to dry and do a moisture test.

YES

More time if possible

 

[BRENT in 10-uh-C]

YES

More time if possible

According to Legacy's Tech Sheet, it states that applying on a damp floor is permissible as long as there is not puddles. Floor looked dry when we left a couple hours ago, and the furnace is holding the room temps around 70 degrees, so we'll see at about 7:30 in the morning. Hope to have the first coat down by 9:00 and then follow-up with applying the second coat around 5:00-6:00. Maybe by Monday morning it should be cured enough where we can start hanging sheetmetal on the walls and prepping for the lift install.

 

[sammons]

There are "edge grinders" that get right up to the edge of the wall.
Vacuum, brush, vacuum.
The denatured alcohol... wtf is overkill if the floor was clean to begin with (before grinding).
One dude that told you what he did has a thread where he does not have a floor that is right. It is blistered... but he is an engineer so it is not his fault, someone else's.
Wags

Just to be clear I did not recommend denatured alcohol, nor is my floor blistering. I came on this forum to share my experience with my epoxy floor, make friends, and get idea, not to justify my credentials to you. The only reason I stated my background was that I deal with these type of companies for a living, and that I am able to follow specs. sheets/ data packages as well. If you have a problem with please feel free to PM me and we can talk about it.

 

[Armorpoxy]

Wiping in generally not required except when inter coating different layers of special coatings that generally need light a reading between coats.

 

[tncatadjuster]

post pics

 

[FJ4FUN]

I'm planning to paint my new shop concrete floor. There are some surface problems that concrete grinding should address. I did some research on the net and know that a local company named Sunbelt Rental rents concrete grinding equipment. If you have done this to your shop floor I would like to hear from you. Good, bad experience? Hints or suggestions. Any and all comments on the process. The surface finish of my concrete has some waves and areas where the surface is not very smooth. I thought the surface finish should have been better but now I need to deal with what is there. I think the grinding process is the best solution or is there something else I should look into? Thank you. Gary R.

SunBelt typically will have everything you need, we send a lot of our customers too them. For smaller jobs under under say, 600sf, the Edco twin head will do you fine. It will take you a little longer and it's a bumpier ride but will cost you a lot less. For larger jobs step it up to one of their Lavina 21" planetary grinders. Always get an appropriately sized HEPA vac and make sure that the grinder shroud is present and in good working order (this is usually not an issue when renting from SunBelt but is almost always one when renting from any of the BigBox stores rental dept as the shrouds tend to get beat up...). Speaking of shrouds, make sure that whatever angle grinder you choose has one! If going the Harbor Freight route include one (or two...) of their universal shrouds. I say two because they're pretty fragile and tend to self destruct. For larger floors rent a good one with a built in shroud. You will also need to make sure that you have sufficient amperage for whichever eq you plan to run, nothing is more frustrating than finding out your E-supply can't run the eq you just rented and brought home and now you have to run out and rent a genny as well! If you do need to step up too a Lavina type machine but don't have the juice to run it you may consider a propane unit if available. The added weight of the propane units will decrease the time spent grinding but they cost more. Also, make sure they include an appropriate extension cord, usually included free of charge, because using an under rated cord can/will damage the grinder. Last, but not least, be sure that they provide a floor wand for the vac! Trying to Frankenstein your shopvac floor attachment to the rental vac with duct tape and bailing wire is no fun.

 

[Two Pump Chump]

This thread has not scared me off !!! 1,800 sf bare concrete right now. The dust !!! Yeehaw !! Much search reading to do. Sounds like I will need a good shop vac for the dust.......

Off topic, but there are qualified people here so . . . .. ..

I need to construct three interior walls to reach a conventional joist loft overhead. Treated 2x6 is onsite, inside and dry. But the outside temps have fallen way way down as low as 16 F already. The unfinished and uninsulated house and slab will not reach the recommended application temp of 50 F until late next spring. I am anxious to make progress and considering applying several inexpensive electric blankets over the base plate runs to slowly heat them up. Then I can glue and stick build the walls. Is this a decent plan ? - thanks

 

[2Rocky]

Sorry to resurrect an old post but how much of a variation can the Edco machines grind down? https://www.calwestrentals.com/equipment-rentals/concrete-dual-head-surfacer/

I've got an old concrete slab with seams and lumps as much as .3 inches high. Do i need to hit those spots by hand with an angle grinder?

 

[Armorpoxy]

Hi 3 inches is like a mile and not recommend to attempt it. You could spend a LOT of time effort and diamond wear depending on how large the area is. If it’s just an edge then ok, but if a large area rethink it. Better off pouring a self leveler and raising the floor to meet the high spots.