shot blasting

[m29C]

Hi Everyone

I am a new member to this forum and would like to know some different opinions on shot blasting a concrete for epoxy paint. I have a reasonably smooth 3 year old concrete floor . The issue is Laitance. My floor has large spots of it all over. I tried the dimabrush which just went over the top of it and really was a waste of time and mess. I tried acid etch and again very slow incomplete removal and needs a large amount of water for cleanup and actually seems to add to the laitance. My shop sq footage is about 800 sq feet. The attractive thing to me on shot blasting is I don't need to use water and it is very low dust. Cost to rent the machine is 350 with the vacuum per day so in talking with the rental people they say if I rent it on Friday and return on Monday I will only be charge the one day rental fee. Grinding is cheaper but way more messy. Any comments would be appreciated

 

[Armorpoxy]

Hi,
We own a large concrete prep company called www.prep-crete.com. Caution on shot blasting!

Using a shot blaster for a novice can be somewhat tricky as if you don't do it right you will get significant 'lawnmower lines'. Also we don't know if the blaster you are renting is self propelled, but if you don't keep it moving perfectly along, you can blast in a deep rut in just seconds. A non self-propelled unit could be even harder to use, and these types of units don't have much 'oomph' and won't do much to your floor. Our blasters which will do a good job for your situation cost in excess of 60k each, run on 3 phase power, and are not 'rentable' since they are not easy to use or operate. 115 v units won't do much since they have very small shot motors hurling the shot.

Lastly, proper shot blasting is a very aggressive prep method and will leave the floor significantly textured, necessitating the need to re-grind to get smoother, or the use of a LOT of epoxy to smooth it out if you want a smooth floor that the texture won't show through. We will rarely shot blast if putting down a thin mil (less than 50 mils) coating with no aggregate, as the lines will show through, and that is even with our experienced operators. Below are some pics showing during and after shot blasting a floor. The lines are quite visible and could telegraph through a thin mil coating.

You may want to consider just covering over your floor with our www.supratile.com solid PCV Polymer interlocking tiles, or similar as a solution.

Also renting the right grinder and vac could be a good choice. A Diamabrush is not the right tool for your problem.

 

[LegacyIndustrial]

Hi Everyone

I am a new member to this forum and would like to know some different opinions on shot blasting a concrete for epoxy paint. I have a reasonably smooth 3 year old concrete floor . The issue is Laitance. My floor has large spots of it all over. I tried the dimabrush which just went over the top of it and really was a waste of time and mess. I tried acid etch and again very slow incomplete removal and needs a large amount of water for cleanup and actually seems to add to the laitance. My shop sq footage is about 800 sq feet. The attractive thing to me on shot blasting is I don't need to use water and it is very low dust. Cost to rent the machine is 350 with the vacuum per day so in talking with the rental people they say if I rent it on Friday and return on Monday I will only be charge the one day rental fee. Grinding is cheaper but way more messy. Any comments would be appreciated

Do it. Shot-Blasting is a great way to go and that is not a bad price.

 

[repomannwp]

I've shot blasted a garage and it came out fantastic. Just keep it moving like you are mowing grass, with just a little overlap each time and for me, I got a perfectly uniform texture in the concrete, and it did not show through the base coat of epoxy.

Shot blasting creates a helluva lot of dust, but IMHO, there is no easier way to prep a floor. I've also used those rentable stand-up diamond grinders and found they were a pain in the *** and didn't do nearly as good a job as a shot blaster.

 

[frankieskiller]

Hey Repo. So, I'm thinking of shot blasting my garage floor (475 sq/ft). I've tried the EDCO single disc grinder but, I was only able to get a few areas down to the raw concrete even after doing 2 passes (took 10 hours).

Anyway, wanted to get your advice on the shot blasting since it worked out great for you. I'm a pretty handy guy but, it's my first time doing this sort of work and I would love to do it all myself without hiring anyone but, at the same time I don't want to ruin the floor.

Also, which brand of shot blaster did you go with? I'm able to rent the national flooring 3395 shot blaster

https://www.nationalequipment.com/en/machines?cat=7&prod=37

Thanks!

 

[Armorpoxy]

Hi we own a shot blasting company www.prep-crete.com so we have a lot of experiences with this process.

A shot blaster only cleans and profiles and is less aggressive than grinding concrete. If you are able to grind your concrete so it has the profile you want that should be fine. Normally the only times it’s needed to grind through the cream cap and into the aggregate is to expose aggregate for polishing to give a ‘salt and pepper’ look, and large industrial 3 phase grinders are needed for this.


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[LegacyIndustrial]

Rental houses (some) offer Lavina and Husqvarna planetary machines. They are smaller versions of the big units, running on 110v. Try and get one of these and see if they have PCD tools.

Dampen the surface an hour before you start and keep it moist.


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[frankieskiller]

Thanks for the input fellas. Definitely learning a lot. I got the concrete clean after grinding it with the EDCO single disc grinder but, I would love to get it all down to the bare/clean concrete if possible. You can see it barely scratched the surface in most spots. Spent 8 hours doing 2 grinding passes. I've never used a planetary or 3 phase grinder before so, I'm wondering if I should have it professionally done at this point or call it a day and move forward with densifying and polishing.

Grabbed some photos for y'all to take a look at when you have a chance.

https://www.flickr.com/photos/140922258@N07/albums/72157675266344587

 

[Billwater24]

Don’t rent a 110v Husqvarna PG 450. I have the 220v model and it’s garbage!!! The 110v model is a joke. A very expensive joke.