Treatment of Concrete Slab

by Nicole

Q: I have an extension that will be my bedroom the floor at present is still a plain grey slab.

I would like to have a slight shine to it, but basically keep it looking the same.

The walls are block and will need to be lined with gyprock should we treat the floor before doing walls?

I think the floor might need a slight grind or sand somehow to make it smooth....and then be sealed?

Thanks for your advice

Nicole

A: Hi Nicole

Here's what I think:

Yes, you will do yourself a favor by taking care of the floor before doing drywall work. No need to have new finishes up prior to working away at the floor, it would just make things more stressful.

Please keep in mind that even though I cannot see your existing floor, prep work is the most important component of your project. The combination of concrete grinding and concrete staining you are looking to do is often known as polishing concrete.

I've written an article on it that I have not yet published, so I will paste it here for you so you can see what making the old concrete floor shiny will entail. If you are planning to use a concrete floor grinder on your own, please be careful and check out the link below the polishing instructions.

How to Polish Concrete

Tools and Materials


* Polishing concrete is somewhat like sanding wood. The tools and materials you need will depend on the results you want. If you want a shiny, perfect finish that doesn't need to be waxed, then you need to rent a polishing machine and a series of diamond impregnated disks of progressively finer grits to get the floor to the degree of shine that you want.

* You start with a coarse disk of diamond pieces in a metallic matrix. These will remove minor blemishes and light coatings. The number of disks you need will depend on the square footage of the job.

* The finer grinding disks also use diamond abrasives that are part of a resin or plastic matrix.

* If you want a high-gloss surface, use a final disk with a grit of 1500 or finer.

* You'll use an invisible sealer during the grinding process to protect and harden the concrete to avoid the need for a topical coating.

* But you may want to use a topical coating anyway.

* Those who want a more matte, "industrial" finish can polish the floor with the same rotary machine, but with sanding disks instead of the diamond impregnated ones. Sandpaper of 36 grit is recommended. This technique leaves a custom, uneven appearance to the floor, but some people prefer this effect to a highly polished "showroom" surface.

Regardless of which grinding method you use, you will need a shop vacuum for cleanup. It should have a HEPA filter (which will likely need to be changed during the course of the project).

Getting Ready

The most important preparatory step is to get the floor clean and dry. Sweep away as much dirt as possible, vacuum, and if necessary mop the floor and let it dry thoroughly.

The rotary machines you rent get closer than you might think to the walls. To do the edges, you can use a palm sander or an angle grinder for the inch or two closest to the walls.

Polishing the Floors

Dry polishing is used for the first steps in floor grinding. Start with the metal-bonded diamond disks, and as the floor becomes smoother, switch to the resin-bonded diamond disks. You can now purchase resin-bonded disks that are made to stand up to the friction generated by dry grinding. With these disks, you may not have to do any wet grinding at all.

To get the high-gloss finish on concrete with diamond grinding disks, you may have to use a combination of wet and dry grinding. The wet process keeps the diamond abrasives cool and eliminates grinder dust. It does, however, create a slurry that has to be cleaned up and collected.

Rotary machines may not be as messy as you expect. After the first, messiest pass over the floor (particularly if you're using sanding disks rather than the diamond polishing disks) you should be able to do a pass, stop, vacuum, then start the grinding again.

If you are not after the high-gloss finish, you can use a penetrating sealer such as AcriSoy, and follow it up with a top coating of a material like PolySoy. These products should get you to a satin finish, so you have just a little shine.

If you're going for a high gloss, you continue using finer disks until you achieve the finish you want.

Nicole, please also check out this page below on using a concrete floor grinder, if you haven't already.

http://www.meet-mr-concrete.com/concrete-floor-grinder.html


Build well,

Alan
Meet-Mr-Concrete.com
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