Ask Me Help Desk - Concrete over asphalt

Concrete over asphalt

I have a garage that has an asphalt floor. The thickness is unknown but it is very uneven. It appears that someone has taken a hand stomper to flatten it down. I have heard that it is not wise to pour concrete over asphalt. First of all I would like to know why it is not wise to pour concrete over asphalt.
Secondly I would like to put rebar over the top of the asphalt to give the concrete the extra strength. Is it possible to pour the concrete over the rebar which would be over the asphalt and not get cracking or is it advisable to remove the asphalt.

The perfect way is to remove the asphalt and add 4" of 2b clean stone. A 6 mil vapor barrier and then pour with 6x6x8 gage wire matt's in Crete and pour 4,000 Psi

Or brake some areas out of the asphalt for dew drainage. After that I would put a 1/2 layer of rice mix stone over the asphalt for the moisture control not to mention the stone being a leveling agent to have a flat base to order the right amount of Crete.

Concrete over asphalt outside is a big NO NO . The reason is rain/ moisture that goes through the concrete gets trapped in/on the asphalt and then freezes and heaves the concrete that's above it. Since you have a roof that situation is greatly cut down. The rice mix stone is for residual moisture in Temp difference.

3/8 bar 2 foot square would be plenty depending on the thickness of the pour.

What was the thoughts in thickness of crete here?

As much of a Headache that it's going to be, your best bet is to just remove the asphalt. Replace it with back fill.

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Originally Posted by 21boat

The perfect way is to remove the asphalt and add 4" of 2b clean stone. A 6 mil vapor barrier and then pour with 6x6x8 gage wire matt's in Crete and pour 4,000 Psi

Or brake some areas out of the asphalt for dew drainage. After that I would put a 1/2 layer of rice mix stone over the asphalt for the moisture control not to mention the stone being a leveling agent to have a flat base to order the right amount of Crete.

Concrete over asphalt outside is a big NO NO . The reason is rain/ moisture that goes through the concrete gets trapped in/on the asphalt and then freezes and heaves the concrete thats above it. Since you have a roof that situation is greatly cut down. The rice mix stone is for residual moisture in Temp difference.

3/8 bar 2 foot square would be plenty depending on the thickness of the pour.

What was the thoughts in thickness of crete here?

Can asphalt be installed over concrete?will the water cause the same problem as you suggest here,also would the asphalt have to be tack coated to the concrete with tar?
I have a very rough finish on a new concrete yard and am considering installing 1 1/2" coat of asphalt over it.
Do you know of any other way to re-coat or improve the concrete finish? Thanks

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Can asphalt be installed over concrete

?
YES Even the states roads are resurfaced in that order.

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will the water cause the same problem as you suggest here

NO. A binder is applied on the old concrete and the new asphalt reactivates that as a sealer. Its "oil" "Tar" and what seals a roof? The problem is reversing the order of concrete over asphalt is the concrete doesn't Hot Seal to the old asphalt and leaves to many micro voids for water to freeze and pop Crete. Not to mention Crete not properly bonding to asphalt well.

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Do you know of any other way to re-coat or improve the concrete finish? Thanks

There are many ways to resurface concrete. Go to your masonry/concrete supply houses
The best manufactures of resurfacing products is "Master Builders".
To give you an Idea if there High tech products. Frequently we use there "Set 45" concrete on re haps. Its approved for our state highways for quick pot hole repairs in concrete roads. Mix it , quick pour, and remove the barricades in 45 minutes and let the tractor trailers drive over it.

Fair warning here. Some of it is that high tech that its more expensive then a re pour.

"Master Builder" products were used on Limerick Nuclear Power Plant for resurfacing Crete there.

Its base Company is out of England.

Again check your masonry /supply house. A throu seal

What shape is the crte now?

Its not in great shape,the finishing was a rushed job,thanks for the info,I looked up the set 45,would this be a suitable product to put a repair coat over the entire yard,600yd2 approx,or is it very expensive?
I didn't realise the highways were constructed using a concrete base with an asphalt surface,it will probably work out best to resurface the yard with asphalt,thanks again

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I looked up the set 45,would this be a suitable product to put a repair coat over the entire yard,600yd2 approx,or is it very expensive?

No that was an example of the mored of products they have and the tech world in Crete.

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I didn't realise the highways were constructed using a concrete base with an asphalt surface

That's what's done After the original concrete highway surface wears out. Its an economical way for road repair. It doesn't;t last as long as re-creating the road.

Thanks for the info.it's been very helpful

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Originally Posted by l2fsaapacihm

Its not in great shape,the finishing was a rushed job,thanks for the info,I looked up the set 45,would this be a suitable product to put a repair coat over the entire yard,600yd2 approx,or is it very expensive?
I didn't realise the highways were constructed using a concrete base with an asphalt surface,it will probably work out best to resurface the yard with asphalt,thanks again

If its just the finish that bothers you, grind the concrete. It will look like terrazzo. Then seal with a 50-50 mixture of double boiled linseed oil and mineral spirits. This comes in a premixed, ready to use product. You can source it on the net