[roberto]

(05-29-2018 06:36 PM)Jetset Wrote:  

The update nobody was waiting for: I went ahead and rented the floor grinder.

The moisture test (taping plastic in several spots) was all good even after a torrential rain, so I leveled my repairs flush and took off all the old paint I could reach, caused a duststorm in my neighborhood, sanded the leftover paint around the walls again for good measure, put down two coats of masonry primer, and then two coats of the one-part epoxy/acrylic paint. It looks pretty legit, some of the spiderweb cracks were too deep to grind out completely, but most filled nicely.

Did not use flakes or anti-skid and did not clearcoat, so I can hopefully just sand and recoat if I need a repair.

Mate, I totally failed you. I'm sorry. Didn't see this

Renting the grinder was a smart thing. You should have rented a industrial dust vacuum to go with it, silicosis is no joke. A cyclone bucket on an industrial vacuum can sometimes keep up. Concrete can only ever be smoothed by abrading, even when you power float it you're still abraiding it, it's just easier cause it's still relatively soft.

Unless it was a decent 'high build' two pack floor paint, you're likely to end up with a very soft floor with four coats of paint. What I would have done is skimmed the low spots and cracks with either a resin product (expensive) or (this is gold) 3:1 mix of kiln dried sand and fast set cement, no water whatsoever (floor must be dry also), and neat SBR to wet it. Bonds perfectly, fills to sub 1mm with a filler knife due to the tiny sand particles and then makes it a pice of cake to grind off the rough top and exposed aggregate. I use this on floors where the stones are maybe 5mm proud as a cheapish rough skim (SBR is still fairly pricey, but no normal sand/cement mix would hold on such a thin layer) Then I grind to a perfectly smooth finish. Resin products are basically kiln dried sand and fibreglass, the princinple is the same and there's no reason they should cost what they do. You can buy fibreglass resin cheap.

With regard to your hairline cracks- you should be able to fill with the above, and then sand down and paint over. The limiting factor will be the bond to the paint, which will likely not be as good as the bond to cement. I have a test patch which I have been meaning to sand down for a while.

If you have small patches then a 'turbo cup' diamond grinding wheel can be had in 180 or 125/115 mm diameters. Couple this with a brush shroud for the grinder which provides dust extraction and you have a cheap mini grinder. You will need an inline cyclone bucket for extraction, otherwise you'll blow a bag and clog the filters in two minutes tops.


Grinding disc


Guard


DIY inline cyclone bucket