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Problem After Grinding; How Smooth?

eriku19tex

Member
Joined
Jul 11, 2018
Messages
8
Location
Houston, TX
Hey Guys,

Looking for some help on my floor.

Long story short - we rented an Edco floor grinder and it was WAY too aggressive. We returned it and rented a "concrete floor prep tool" (American Sanders) with a diamond coated flap disk on it. It worked better - smoothed out the damage the Edco left and overall did what we needed - prepped the floor and gave it a nice profile for epoxy. wish I would have rented this first.

The problem now is I have some areas on the floor, say 1/4 of the garage, where the concrete is rough/not smooth. It almost looks spalled. Certain areas have part of the original "cap" and then adjacent to it rougher concrete that is maybe 1/32 to 1/16th of an inch lower.

I've tried hand grinding these areas with a cup disk and hard masonry disk - but again it is too aggressive and removes too much material (much like the Edco). A 40 grit flap disc was better at smoothing it out and easing the transitions but it certainly isn't as smooth as the other area of the floor

The finish: Armorseal 33 prime, 650 epoxy, rejection broadcast of flakes, 650 epoxy and then HS topcoat the floor - a solid finish - but obviously prep is everything and I don't want to put a great finish that's just going to show a poorly prepped floor.

I come from a wood finishing background, so I may be over thinking how smooth this needs to be (if it catches your finger you can see it type thinking) - I don't want these imperfections to coming screaming out when light hits them though :)

what do I need to make this concrete right?

The first picture, along the wall, is the worst area - the second and third pictures were after I hit some of the problem areas with the 40grit flap disc. better for sure - and I can do this where it is needed, just want to make sure that is what's needed.
 

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Armorpoxy

Well-known member
Joined
Aug 18, 2013
Messages
3,735
Location
NJ
The Edco and hand grinder should have not removed the 'cap' so it appears you have some defective concrete that wasn't finished properly. Our suggestion would be to prep this well to remove any other cap that may be thin/flaking and then do a full broadcast or similar to cover it up. Attempting to grind it smooth would be difficult without a very large commercial grinder.
See this link for some helpful info on corroded/defective flooring.

https://254gg219z24i1qbcah3y1wxe-wp...t/uploads/2017/11/CORRODED-FLOOR-BULLETIN.pdf
 
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eriku19tex

Member
Joined
Jul 11, 2018
Messages
8
Location
Houston, TX
Thanks for the reply :)

The cap was removed as a result of how much we had to take down to fix what the Edco had done. so, I think it is more our fault then the concretes (as much as I would like to blame it though!)


When grinding, some of the floor seems to come up like sand leaving a coarse finish, while other areas grind smoother.


Would skimming the floor make more sense? i'm having a specialist come out today to tell me what he thinks - nothing like a little DIY adventure gone south.


a full broadcast was definitely planned - maybe something with a little more build now though lol. I have about 575sq ft - want to send me a quote of what you recommend?
 
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