Epoxy floor Prep... Soft concrete?

[rob328is]

Hi, this is my first post on GJ. I found out about this forum not too long ago and have been hooked ever since.

I'm currently in the process of prepping my garage floor for epoxy. When I first moved into my house, the garage floor looked like a warzone. I had new concrete poured. This was back in Nov 2010. I'm not sure, but it appears to me that my concrete guy may have done a crappy job. Unfortunately I did not know as much about concrete as I do now.

Here is my issue. The concrete appears VERY soft. I have a couple of cracks that formed on the concrete that I was easily able to open up with a flathead screwdriver. It was too easy which got me concerned. I then proceeded to take the flathead to a smooth portion of the concrete and was able to create a groove on the surface with very little effort. I've attached pictures showing my issue.

My question is how should I proceed? My concrete does not have a sealer so my original intention was to do an acid wash, patch the cracks, then proceed with the epoxy (primer, base coat, top coat). But if I do have soft concrete, I would have to address that issue before applying the epoxy otherwise it would a complete waste.

Also, what do you guys recommend for patching the cracks/divots? I tried purchasing the Legacy HD105 but unfortunately they do not ship to So Cal. I hear good things about MG-Krete but I can't seem to find that product for the life of me.

Thanks.

 

[ConCretin]

You obviously suspect you have a problem and unfortunately I think you're right. At a minimum, the surface of your slab is deficient and the problem could go deeper. Either way, I think you need to rethink your plans to apply epoxy. There are more knowledgeable people on here about epoxy than me but I wouldn't trust that surface to hold down an expensive epoxy floor.

You should not be able to open up the crack or gouge the surface that easily. It could be a finishing problem or it could be the concrete itself. The only way to be sure is to hire a testing lab. I'm not sure it matters at this point because the contractor is probably long gone but your slab appears to have serious limitations.

 

[rob328is]

Well this is disappointing. There is no way of hardening the concrete? If not, it seems like my only option for epoxy is to get my slab repoured? Oh man...

 

[kyles974]

Rob, PM Scotty from Legacy Industial. He helped me with some concrete issues. I had "sandy surface" on my new slab. There is a hardener that can help harden concrete...... although, I'm not sure if this can help you, but when I applied it on mine, I noticed a huge difference when I hit the concrete with a hammer in the spots I applied vs. the spot I had not applied the hardener. In fact, I was pretty impressed.

 

[grissom]

Rob, PM Scotty from Legacy Industial. He helped me with some concrete issues. I had "sandy surface" on my new slab. There is a hardener that can help harden concrete...... although, I'm not sure if this can help you, but when I applied it on mine, I noticed a huge difference when I hit the concrete with a hammer in the spots I applied vs. the spot I had not applied the hardener. In fact, I was pretty impressed.

Whats the name of the product?

 

[rob328is]

I'll shoot a PM over to him. Thanks Kyle.

 

[ConCretin]

Well this is disappointing. There is no way of hardening the concrete? If not, it seems like my only option for epoxy is to get my slab repoured? Oh man...

There are ways to improve the performance of the surface and make the slab more serviceable. There are guys on here who can help with that. I'd just be leery of applying an expensive epoxy floor over your existing surface.

I'd also be a little concerned about the integrity of the slab as a whole. in addition to the weak, chalky surface, it appears there are extensive shrinkage cracks,all of which might suggest a very wet mix.

Sorry to be so negative. I hope I'm wrong.

 

[dcs Inc]

This looks as if there was a topping applied over your concrete. I've been a concrete contractor for 40 years and have never seen a poured slab act this way. It's been topped. Looks like a gypecrete underlayment type of material. Very low cement ratio....if it has cement in it. Could be a gypsum base.

There's no "quick" cure for this. A surface hardener or densifier will be a waste of time. It's going to go south on you. I'd chisel down to see the aggregate and how deep you need to go to find it. Even sand mixes they apply on pool bottoms wont dig out like that.

Wow, just went back a reread your post. This was actually poured from a ready mix truck? Unbelievable. It must have been poured with a huge amount of water in the mix and very low cement content. Was this guy an actual concrete contractor?

I can see by the finish it wasn't finished correctly. The unevenness of the surface fines shows a lot of water was used either applied topically during finishing or mixed into the batch. If it was blessed at the time of finish (water sprayed on the surface to get a closed finish) then the soft surface can be taken off and an overlay can be applied and then epoxied. In any case I feel someone in the know needs to tackle this. This really isn't a diy project. In other words, applying an epoxy on this is like putting lipstick on a pig.

 

[kyles974]

Whats the name of the product?

I can't remember, but it's a densifier.

Also, I'm sure Scotty or some of the other great epoxy company reps that are active here will speak in Monday.


Just hang in there. I had some post in my thread about "sandy concrete," that my concrete was bad, rip it out and start over, etc.,
(had me all upset for nothing)

 

[dcs Inc]

They come in different flavors. Potassium, sodium, lithium based. Lithium based products are the better of the 3. I'm sure the "great epoxy company reps" will help you out.

 

[rob328is]

Dcs inc: the concrete wasnt from a truck. I remember stopping by while my house was getting worked on. It was two guys, a mixer, and a huge scoop material. I remember thinking to myself at the time, "wow, woudnt it be easier to just have a truck come by...."

If i only wouldve known back then what i know now....

 

[dcs Inc]

That's unfortunate. I honestly don't see this as a viable, long lasting slab. You really don't want to spend any money coating this. It would only be a short term answer and it won't last. This will need to be replaced sometime in the future. I'd just get as much time out of it as you can then have it re-poured correctly, sorry. gene

 

[ConCretin]

I agree with dcs Inc. ***** but no sense sending good money after bad. The good news is that ripping that concrete out will be relatively easy. If you decide to replace it at some point, check back if you need any advice.

 

[LegacyIndustrial]

Thanks to Gene and Kyle for putting us in a "GREAT" category.

Rob, have you considered putting RaceDeck over this concrete?
If it were mine I would cover the thing with RaceDeck, this should hide it forever.

 

[Oggy]

Thanks to Gene and Kyle for putting us in a "GREAT" category.

Rob, have you considered putting RaceDeck over this concrete?
If it were mine I would cover the thing with RaceDeck, this should hide it forever.

Wouldn't RaceDeck be hiding a problem? There's obviously something wrong here, and it needs to be addressed. Putting RaceDeck down, to me would be the equivalent of putting sheetrock up to cover a hole clear through to the outside of the building. The problem is going to surface sooner or later.

I'm not saying that putting RaceDeck down is a bad idea, but I wouldn't put it down and forget that the problem exists. If it were me, the first thing I would try to do is get in touch with the contractor, and take it from there. But covering it isn't the solution.

 

[pauls340]

Rob, I'd be interested in knowing what caused your problem. You might want to do what dcs suggested and pick a spot and dig down to see if you ever find hard concrete. Remove and replace would be easy and you should hope the same crew didn't do the garage footings. If you want to find a stocking Mg-Krete distributor, go to www.imcotechnologies.com to find one, but I wouldn't apply MGK until you determine what you have.

 

[Garage-Tech]

I'm going to agree with the other posts above and conclude that the concrete mix was to wet. It looks like your options are limited.

-Your best course of action find the contractor who did the work and have them address the issue. (This is the least likely to happen)

-Your next option is to repair the slab at your expense, and then apply your epoxy (Very expensive and time consuming)

-As long as the slab is structurally okay you could put down racedeck. (This seems to be the most viable and cost effective option for your floor problem.)

Epoxying over that existing concrete is a gamble at best. You could get lucky and grind down to some aggregate or you could find nothing. Either way it could get expensive really fast.

I hope everything works out, and other GJ members might have some better ideas...

 

[rob328is]

Thanks for all the advice guys. It's a long shot, but I'm going to see if I can get in contact with the contractor who poured the slab. I was pressure washing the garage today just to clean it out a bit and to see what would happen. Mind you, my pressure washer is only an electric rated at 1500psi. Some areas of the concrete started chipping away when exposed to the high pressure water. Afterwards, it looked like sand paper.

Honestly, my instinct is to rip out of the concrete and re-pour but I'm having a hard time justifying that route with myself. Nevertheless, I am going to call up a few concrete contractors to get a quote. My garage only 400 sqft.

I started to think about going with Race Deck. It seems like it may be my only option at this point. My plan was to purchase the densifier from Legacy and then lay down Race Deck. You guys think thats a good idea or just a waste? Should I just cover the concrete with Race Deck and call it a day?

 

[Edger]

If you tile over it you should eliminate most of the problems and end up with a good job. Cheaper than epoxy too by what these guys say. Slickgt has a thread here http://www.garagejournal.com/forum/showthread.php?t=95966&highlight=slickgt and Jack Olsen gives good advice on the method to tile with a heavy base under the tiles.

 

[NotV8]

I will take LLWillysfan advise... he knows concrete!!! Did you check his garage/house build?

 

[pauls340]

Rob, what ever happened with your floor? I just got off the phone with a contractor in Pt Huron who ground a garage floor, vacuum, blower, 1/4" of Mg-Krete (he now wishes he used Mg-Krete Self Level) and then he used an Increte product over it. Came out beautiful. My concern with your floor, all repairs are only as good as its substrate and your floor as a substrate might not be too good.The pic below is one garage we did in sunny 15F winter day!