Floor Too Rough After Grinding

[zdumpor]

I rented a single head Husqvarna PG280 and 6 30 grit inserts. I grinded dry. I am about 1/2 way through grinding the floors once and have hit a road block.

I have two areas that I'm preparing for the High Solids DIY kit:
1. New Concrete 3 months old
2. Old Concrete 1988

The first section (180 sq ft) went about as I expected and didn't wear the inserts too bad. Maybe 1/4 down.

The second section with the old concrete was about the same square footage and wore them down completely.

I have two questions:
1. I have attached the pictures of the old concrete after grinding. The concrete looks pretty rough. Does this look right to you, or will this concrete be a bad foundation for the epoxy kit?
2. Should I expect to go through an entire set of inserts within 300 sq ft, or is that abnormal?

Before I continue with the job, I want to make sure I'm on the right track, and don't want to dump another 150 dollars on inserts and apply the epoxy if it's doomed to fail.

 

[Augus7us]

The spots you ground look good to me. You want it porous like that so the primer leaches into the pours and makes good connection with the floor. Otherwise it will peal up. I ground the **** out of my floor and have not had any delam issues with the epoxy after 3 years. I have a full flake floor and drive my truck and forklift on it all the time. Still looks new if I mop it.

 

[Zeke]

Should be in flooring forum.

Looks too rough to me. I've done lots of coatings work, but not floors. So take it for what it's worth.

 

[P0234]

It's hard to tell by scale. Stick a penny on the floor and take another picture of the worst area.

 

[zdumpor]

Understood, Zeke. I had originally posted ther, but it required approval. After about 3 hours I posted in general.

I feel a bit better about the grinding today. I ran it much faster and with water. It burned through the second set but roughed up everything well. The small spots I’ll do with a hand grinder since I have to Do the sides.

Here is a few pics of the really rough spot. Had a key for scale.

 

[BillK]

Im not a flooring guy but that looks very rough to me.

 

[Augus7us]

Its fine as long as you get a quality epoxy, 90%+ solids. Dump a cup of water on it, you want it to be absorbed quickly, if it does the floor is good. The divits are probably from using a single disc grinder. Three disc are much better at preventing this.

Do you have a photo of the inserts? I've done a couple of these and I've never ran through a set in one go. My shop was 1200 sq ft.

 

[zdumpor]

I used the Hiskvarna 200 series 30 grit inserts…I think they’re a medium hardness.

From what I read, the soft concrete can chew up inserts. Apparently the hard ones are much better for soft and Soft is better for hard concrete. The Sunbelt only had the medium.

 

[P0234]

Not a pro either but it looks like it’s going to drink up a lot of epoxy. Hopefully one or two of the pros see this and comment. You are right to have some concerns.

 

[zdumpor]

Agreed.

I got an email out to Garage Floor LLC.

Most of the rest of the floor is less aggressive.