Spalling Garage Concrete Repair

[kgall]

I've attached some pictures of my garage concrete spalling significantly, exposing rusted rebar. I'm trying to tackle the repairs myself and needed some input to ensure I'm on the right track. In the process, I've found a hollow space below the concrete slab. I have a company coming to assess the extent and if there are any foundation issues present. Here are the steps I've mapped out based on the forums I've read. This seems really overwhelming but all I've read makes me feel like I'm capable of completing this project without shelling out several thousand dollars for pros, barring any significant foundation findings from the assessment.

1. Demo: tear out all the loose, hollow-sounding concrete
2. Fill space beneath concrete slab using https://www.secureset.net/product/secure-set-spray-foam/ covering 16.6 ft3 (supports 5,000 lbs/ft2, cost ~$500
3. Buff out the rust on the rebar, prime with Corroseal Rust Converter, cover with Seymour Green Epoxy Rebar coating
4. Clean garage floor with Rustoleum Cleaner/Degreaser/Etch
5. Fill holes around rebar concrete or FiveTon Epoxy https://www.legacyindustrial.co/products/fiveton-epoxy-patch-kit/ large kit covers 16-18 ft2 @ 0.25 inch depth, cost ~$200 Question: Is it better to use concrete bond, fill with concrete, and put FiveTon over the top or should I fill entirely with FiveTon?
6. Cover floor with Rustoleum Recoat Primer ~$100
7. Cover floor with Rustoleum RockSolid Coating ~$200
8. Cover floor with Rustoleum RockSolid Clear Topcoat ~$200

Question: Are these steps correct and are there better/more cost-effective options available? Am I crazy to think I can do this effectively myself and not compromise the integrity of the garage supporting the weight of our cars (~3,400 lbs and ~4,800lbs)?

Thank you so much for all the help.

 

[zc15]

Paging @LegacyIndustrial for some of these questions as I am somewhat interested in the answers too

 

[benwah]

That is much more than simple spalling. That concrete is failing, or has failed.

I would suggest core samples before you plan to do anything.

Also, you don't want to use Rustoleum lol

 

[kgall]

That is much more than simple spalling. That concrete is failing, or has failed.

I would suggest core samples before you plan to do anything.

Also, you don't want to use Rustoleum lol

Sorry, should have included the picture was after step one.

Could you clarify which step to not use Rustoleum? And provide a better alternative and justification?

Thanks!

 

[benwah]

Sorry, should have included the picture was after step one.

Could you clarify which step to not use Rustoleum? And provide a better alternative and justification?

Thanks!

Ahh, I gotcha .

Do you know what caused that to fail? IMO without doing some core testing I would be hesitant to recommend a fix right off the bat.

I would not use Rustoleum for any step, ever. They are bottom of the barrel coatings. They use cheap raw materials and their coatings are not industrial grade.

But the testing is important. If you are maybe not willing to go that route, possibly Race Deck type tiles may be your best bet, after the repair.

Also, if you are dead set on resinous coatings, after that entire floor is patched, or re-poured, it will need to be ground to an ICRI CSP 2-3, just keep that on mind. But once again, I would highly suggest some core samples before anything. That's my .02

 

[benwah]

And I am not just saying that to be difficult, I just went through a very similar experience with the Forest Service building in Gunnison Colorado.

I was supposed to do a 10000 ft² large aggregate Polish. The framing contractor dumped a bunch of ice melt on the slab and Left it on there for a couple weeks. It ended up blowing out every joint in the building so I was looking at major joint repairs and spalling repairs. The owner and government wanted to go ahead with thePolish but myself and the architect highly recommended core samples. Once the lab reviewed the samples they deemed the slab was structurally unsound and it had to be entirely demo'd and re-poured.

The last thing you want to do is repair a failing substrate because it will only continue to fail and then your money and hard work is down the drain for nothing. Someone else may have something different to offer, but that's about where I stand until it is deemed structurally sound.

 

[kgall]

And I am not just saying that to be difficult, I just went through a very similar experience with the Forest Service building in Gunnison Colorado.

I was supposed to do a 10000 ft² large aggregate Polish. The framing contractor dumped a bunch of ice melt on the slab and Left it on there for a couple weeks. It ended up blowing out every joint in the building so I was looking at major joint repairs and spalling repairs. The owner and government wanted to go ahead with thePolish but myself and the architect highly recommended core samples. Once the lab reviewed the samples they deemed the slab was structurally unsound and it had to be entirely demo'd and re-poured.

The last thing you want to do is repair a failing substrate because it will only continue to fail and then your money and hard work is down the drain for nothing. Someone else may have something different to offer, but that's about where I stand until it is deemed structurally sound.

I don't think you are being difficult, and thank you so much for your replies! They are extremely helpful as I am completely out of my element and am trying to do what is best monetarily and structurally.

I can speculate on a few reasons the concrete failed.
1. I can remember finding a hole at the front of the garage near a downspout where water would pour in. I patched the hole 8 years ago and have been putting off any garage repair since. When I broke through the bottom of the concrete it appeared dry underneath.
2. Standing water seeping in from the garage drain and old iron pipes that seeped into the surrounding ground/concrete that led to spread of water and rust along rebar.
3. Years of neglect from the previous owner from deicer/salt/water carried in from their cars. The majority of the damage seems to be focused around where the front tires typically lie.

 

[kgall]

And I am not just saying that to be difficult, I just went through a very similar experience with the Forest Service building in Gunnison Colorado.

I was supposed to do a 10000 ft² large aggregate Polish. The framing contractor dumped a bunch of ice melt on the slab and Left it on there for a couple weeks. It ended up blowing out every joint in the building so I was looking at major joint repairs and spalling repairs. The owner and government wanted to go ahead with thePolish but myself and the architect highly recommended core samples. Once the lab reviewed the samples they deemed the slab was structurally unsound and it had to be entirely demo'd and re-poured.

The last thing you want to do is repair a failing substrate because it will only continue to fail and then your money and hard work is down the drain for nothing. Someone else may have something different to offer, but that's about where I stand until it is deemed structurally sound.

I have an appointment this Friday to assess the damage and will try and get some core samples. It sounds like there are 2 paths forward here: structurally sound and not.

Structurally unsound: completely demo and repour concrete pad.

If it is deemed structurally sound, what changes would you make to the steps and materials I have above? As I said, I want to be fiscally conscious, but also don't want to have to redo this project in 5-10 years.

 

[ConCretin]

The challenge isn't supporting the weight of your cars, the base below the slab is doing that.

Repairing the deterioration isn't really all that complicated either. I'm not familiar with the products you mention but the goal is to encapsulate the rebar so it doesn't continue to rust, expand and spall the concrete. We've done a lot of bridge deck repairs using Armitec 110 on the rebar and cementitious repair mortars, which I prefer over epoxy for a number of reasons.

The challenge is the existing concrete around the repairs. It's virtually certain that those areas will continue to deteriorate and pose problems down the road. If your not interested in a complete replacement, you can keep making repairs and extend the life of the slab but there is no way I'd invest in an expensive coating.

Btw, unless you are willing to invest in an expensive petrographic analysis of the cores, all they will tell you is the compressive strength of the concrete. Even if that's fine, there could be a lot of other issues that breaking cores won't show.

 

[mcbane]

I don't think you are being difficult, and thank you so much for your replies! They are extremely helpful as I am completely out of my element and am trying to do what is best monetarily and structurally.

I can speculate on a few reasons the concrete failed.
1. I can remember finding a hole at the front of the garage near a downspout where water would pour in. I patched the hole 8 years ago and have been putting off any garage repair since. When I broke through the bottom of the concrete it appeared dry underneath.
2. Standing water seeping in from the garage drain and old iron pipes that seeped into the surrounding ground/concrete that led to spread of water and rust along rebar.
3. Years of neglect from the previous owner from deicer/salt/water carried in from their cars. The majority of the damage seems to be focused around where the front tires typically lie.

4. Maybe whoever placed the slab saved some time by using calcium chloride to accelerate the set.

 

[LegacyIndustrial]

Paging @LegacyIndustrial for some of these questions as I am somewhat interested in the answers too

Put that 5Ton right to the concrete gents!!!
Dry and dust free concrete, it will stick like the dickens!

 

[LegacyIndustrial]

Put that 5Ton right to the concrete gents!!!
Dry and dust free concrete, it will stick like the dickens!

It will stick to clean metal as well

 

[kgall]

The challenge isn't supporting the weight of your cars, the base below the slab is doing that.

Repairing the deterioration isn't really all that complicated either. I'm not familiar with the products you mention but the goal is to encapsulate the rebar so it doesn't continue to rust, expand and spall the concrete. We've done a lot of bridge deck repairs using Armitec 110 on the rebar and cementitious repair mortars, which I prefer over epoxy for a number of reasons.

The challenge is the existing concrete around the repairs. It's virtually certain that those areas will continue to deteriorate and pose problems down the road. If your not interested in a complete replacement, you can keep making repairs and extend the life of the slab but there is no way I'd invest in an expensive coating.

Btw, unless you are willing to invest in an expensive petrographic analysis of the cores, all they will tell you is the compressive strength of the concrete. Even if that's fine, there could be a lot of other issues that breaking cores won't show.

"In the process, I've found a hollow space below the concrete slab."

So there's no issue with weight support despite this hollow space?

Thanks for the reply!

 

[kgall]

Put that 5Ton right to the concrete gents!!!
Dry and dust free concrete, it will stick like the dickens!

Thanks for the reply! I think I understand the utility of the 5Ton, my question was more to do with the use of concrete to fill the hollow concrete I removed. I think they are too big to be filled with just one large kit of 5Ton, meaning I would have to buy multiple kits. I have 6-7 bags of concrete that were given to me that I could use in lieu of buying more than one large 5Ton kit to go over the top of aforementioned concrete. The Question is: If I were to apply rust converter and seal the rusted rebar with epoxy paint, would filling the deep holes with concrete and then applying 5Ton over the top of that to level it out make a more solid, less solid, or adequate repair than using multiple kits of 5Ton to fill the entire deep holes?

 

[ConCretin]

"In the process, I've found a hollow space below the concrete slab."

So there's no issue with weight support despite this hollow space?

Thanks for the reply!

Sorry if I missed that part. The hollow spot is definitely a concern. A slab on grade isn't structural and can't span very far over voids or soft ground. There are a number of ways to address the voids but you might be getting to the point where the number of deficiencies brings the viability of salvaging the slab into question.

 

[LegacyIndustrial]

Thanks for the reply! I think I understand the utility of the 5Ton, my question was more to do with the use of concrete to fill the hollow concrete I removed. I think they are too big to be filled with just one large kit of 5Ton, meaning I would have to buy multiple kits. I have 6-7 bags of concrete that were given to me that I could use in lieu of buying more than one large 5Ton kit to go over the top of aforementioned concrete. The Question is: If I were to apply rust converter and seal the rusted rebar with epoxy paint, would filling the deep holes with concrete and then applying 5Ton over the top of that to level it out make a more solid, less solid, or adequate repair than using multiple kits of 5Ton to fill the entire deep holes?

Sorry, I am resistant to recommend concrete for any application under 4" thick for obvious reasons.
If the void is 4" thick I would use our 5Ton exclusively.

If the void was 6", I would fill with concrete right to the top and call it done.

Hope this helps and if you do put the concrete under our 5Ton, make sure it has cured fully before applying our product.
Thanks and good luck.