Finish an old concrete slab?

[JosephNY]

I'm renovating an apt in a building built in 1960.

The floor was wood parquet glued (black, horribly tough stuff) to a 7" thick concrete slab w/rebar and large stones.

My wife is determined to have a beautiful concrete floor.

I'm wondering if the slab can be ground/sanded/buffed/sealed and work well as the finished flooring. Is there any reason structural concrete couldn't be made to look as nice as concrete made for interior residential flooring?

Here's some pics of the concrete now (with the glue still stuck to it).

Thank you,

Joseph

 

[havasu]

I don't see why not. Your biggest concern would be visible cracks, and how to deal with this before sealing. Are you also planning on staining the floor?

 

[Ernesto]

You can do the loft/warehouse look on any old slab. Get the adhesive off first with a scrape away, then grind down to the aggregate, not to deep. Seal it and epoxy it.

Walgreens just threw up a new Large stand alone near me. They finally got smart and finished the new concrete, no VCT. Who ever did it did a fine job of it too!. All their stores here that have vct also have moisture issues.

 

[Incognito]

I don't know of anything special with regard to "structural concrete" just because it's a 7" slab as opposed to the standard 3 1/2"-4" depth. Should be basically the same kind of batch/mixture for your purposes. If they modify this or that as far as the ratio of sand, cement, aggregate, water and possibly some magic dust to make it set faster or increase PSI strength that's not going to matter to you in this instance.

So whatever was glued to the surface can certainly be scraped, ground off and perhaps shot blasted to get down to PURE concrete. By that I mean whatever residue of the adhesive that's penetrated and discolored the pores CAN be erased if you have the time and money to dig down into the slab that deep. The thing is that the STAIN from the adhesive can go pretty deep, depending on how porous the slab is and how much solvent was involved. In those days the adhesives were HEAVILY laded with solvents, unlike anything you can find today. So that shit STUCK......like forever if they did it right.

As with a "distressed" wood though it's easier------MUCH easier and MUCH more economical to stick with the "rustic" image. Instead of trying to make it look like something new you need to incorporate the existing blemishes into a new, creative look by going deeper and darker with another stain. Then a sealer.

 

[Floorist]

One of the local stores is in an old Walmart building. They removed the VCT, cleaned and polished the floor and it looks good.

 

[JosephNY]

Thank you all so much for your insight and advice.

I've hired a guy who has tons of experience grinding/polishing concrete as well as having an artistic eye.

We'll start grinding and see what we find as far as cracks, blemishes, aggregate, etc. and take it from there.

We're not going for pure and sanitary, but rather, beautiful, different and unique.

 

[havasu]

Please post pics so others will learn how ugly concrete can be transformed into a beautiful flooring.

 

[JosephNY]

Please post pics so others will learn how ugly concrete can be transformed into a beautiful flooring.

Great idea -- will do.

 

[DarisMulkin]

Great idea -- will do.

If possible could you do it in a kind of step by step way? Kind of nice to see how it progresses.

Daris

 

[JosephNY]

Update: The guys started 2 days ago. The black mastic stuck to the floor and applied in 1960 to hold down 9x9 oak parquet on concrete is far more difficult to remove than anticipated. They tried several machines/blades as well as mineral spirits with and without sand, etc. It's getting there, but it's slow.

Below are pictures at the start, after day 1 and after day 2. More to come.

 

[JosephNY]

And more:

 

[JosephNY]

Last batch today:

 

[Floorist]

Thanks for the pictures.

 

[havasu]

That is gunna turn out fantastic. Please keep the pics coming!

 

[JosephNY]

Thanks guys!

They're shooting for finishing the removal of the mastic today and a first grind tomorrow.

Will keep the pictures flowing.

 

[Incognito]

Thanks guys!

They're shooting for finishing the removal of the mastic today and a first grind tomorrow.

Will keep the pictures flowing.

****************************
WOW!

I told you it's POSSIBLE.........but hard to tell how much is involved until you're knee deep. I wonder if this guy knew what he was getting into? He sure looks like he's done this before.

Thanks for sharing those pictures.

It's like Mother's Milk to a flooring guy!

 

[JosephNY]

The owner of the company and a couple of guys have all done this many times.

But, as they've said, each job is different.

This mastic, they say, is the worst they've ever seen. It's 60 years old, put on thick, and gums up their machinery.

They didn't finish today, but they're much closer -- the mastic should be gone by mid-day tomorrow (I hope).

I'll take pics in the morning to show today's accomplishments.

Something very weird: As I see the concrete with aggregate slightly ground I have this odd memory/sensation from childhood (decades ago). The best I can do to explain it is that terrazo was more common in doctor's office and other commercial or quasi-institutional places and seeing the concrete is bringing back feelings from being a kid in the 70's.

 

[JosephNY]

Here's progress -- Mastic is gone, they're starting the first grind now.

 

[JosephNY]

Here's some from this morning (yesterday's work).

All mastic is up. Grinding has started.

I'm told that some mastic is in holes/cracks and needs to be drilled out - ugh.

And, that in some places the mastic stained the concrete below a little bit.

I'm very open to (and would be appreciate of) any suggestions/comments/advice.

 

[Ernesto]

Go with a charcoal stain.

Actually I'd go Ardex topping with colors since that slab is a POS.