[rranger]

A new poster on here with some questions. I noticed this forum and saw many knowledgable posts on concrete and ashphalt. Hopefully I can get some direction.
A few years ago I hired a skid steer to dig up what I thought was my asphalt driveway. I was going to replace it with concrete. While I was at work the skid steer operator found a solid layer of concrete under the ashphalt and just sheared off the layer of ashphalt leaving The concrete alone. The concrete still had ashphalt residue on it. I left it alone. Last summer the seal coaters were in our neighbourhood and I paid to have them put a coat on it. Looks ok but I have some drainage issues I'd like to correct and am revisiting pouring 4 inches of concrete on top what I have. I've priced concrete compared to ashphalt and I'm hearing 4 times as much for ashphalt over concrete. Seems excessive.
Is the seal coating going to cause any adhesion issues? Do I need to put plastic or something in between? Is a new layer of 4 inches of concrete enough? Do I need wire? Any other ideas?
Thanks any and all input will be appreciated?
Any advise would be greatly appreciated.

 

[jimn]

Hopefully you will get Bondo's advice. Probably the best expert on all things concrete and excavation . Some how I think that seal coat is going to be a problem

 

[Bondo]

I've priced concrete compared to ashphalt and I'm hearing 4 times as much for ashphalt over concrete. Seems excessive.

Ayuh,.... Thank you for the vote of confidence Jim, but I'm just a blacktopper with 20 odd years experience,...
Concrete, not so much,....

That sure does sound odd that concrete is cheaper than blacktop,....
Highly unusual,....
Where are ya located,..??
Pictures may well help too,....

If ya cover the entire area with 4" of concrete, yer puddles will still be where they are now,...
So,....
Ya need to survey the area with a lazer level to see where, 'n how much drop ya need to create pitch to move the water away,....
It could be 4" in one area, to nothin' somewhere else,....

As far as the concrete stickin' to the existin' concrete, it rarely does,...
Gravity holds it in place, not so much bondin' to the lower layer,....
Ditto with asphalt,... the size/ mass, 'n gravity hold it in place,...

 

[rranger]

Ayuh,.... Thank you for the vote of confidence Jim, but I'm just a blacktopper with 20 odd years experience,...
Concrete, not so much,....

That sure does sound odd that concrete is cheaper than blacktop,....
Highly unusual,....
Where are ya located,..??
Pictures may well help too,....

If ya cover the entire area with 4" of concrete, yer puddles will still be where they are now,...
So,....
Ya need to survey the area with a lazer level to see where, 'n how much drop ya need to create pitch to move the water away,....
It could be 4" in one area, to nothin' somewhere else,....

As far as the concrete stickin' to the existin' concrete, it rarely does,...
Gravity holds it in place, not so much bondin' to the lower layer,....
Ditto with asphalt,... the size/ mass, 'n gravity hold it in place,...

I live in Grand Forks BC 2 hours north of SPOKANE Wa right on the border. Yes I've got some sloping to do. The ashphalt quotes were laughable, maybe they are to busy and don't want small jobs.
So should I put a layer of plastic down with wire and a minimum 4 inch pour. And what would you recommend for a distance between joints for a single 60 foot long driveway?
Thank you.

 

[rranger]

No pics right now. It's covered in snow.

 

[Bondo]

So should I put a layer of plastic down with wire and a minimum 4 inch pour. And what would you recommend for a distance between joints for a single 60 foot long driveway?

Ayuh,.... Can't see any reason at all for a sheet of plastic,....

Steel is Always required in concrete,...
especially a driveway, more steel the better,....
Joints, 'n saw cuts in concrete control the crackin' that always happens with concrete,....
The idea is, it'll crack at the cut/ joint, rather than randomly,...
I'd think an 8' or 10' pattern might be enough, but again, I'm a Blacktopper, not so much into concrete,....

 

[Canarywood1]

I live in Grand Forks BC 2 hours north of SPOKANE Wa right on the border. Yes I've got some sloping to do. The ashphalt quotes were laughable, maybe they are to busy and don't want small jobs.
So should I put a layer of plastic down with wire and a minimum 4 inch pour. And what would you recommend for a distance between joints for a single 60 foot long driveway?
Thank you.

It all depends on the condition of the concrete that was uncovered, are sections of it heaved, how wide are the existing cracks?

 

[rranger]

It all depends on the condition of the concrete that was uncovered, are sections of it heaved, how wide are the existing cracks?

The concrete is not heaved and no crack has totally separated pieces of concrete. Just some surface cracks. My plan is to repair any cracks first.

 

[Canarywood1]

The concrete is not heaved and no crack has totally separated pieces of concrete. Just some surface cracks. My plan is to repair any cracks first.

Really no need to repair any small cracks then, but use a bond breaker just in case so they don't telegraph through, and wire mesh if you like, control joints should be 2/3 times in feet, the thickness of the slab in your case if 4 inches no more than 8/12 feet apart, an even number for a 60 foot drive would be 10 feet apart, and make for a uniform appearance.

 

[Bondo]

The concrete is not heaved and no crack has totally separated pieces of concrete. Just some surface cracks. My plan is to repair any cracks first.

Ayuh,.... A Wasted effort,...

If possible, align yer cuts/ joints with the cracks there now, cause it'll probably crack again there, no matter what ya do,....

 

[Canarywood1]

Ayuh,.... A Wasted effort,...

If possible, align yer cuts/ joints with the cracks there now, cause it'll probably crack again there, no matter what ya do,....

It's why i said to use a bond breaker, to help to avoid that happening.

 

[rranger]

It's why i said to use a bond breaker, to help to avoid that happening.

Can you enlighten me on the bond breaker please. I googled it but am not sure what I should use.

 

[Canarywood1]

Can you enlighten me on the bond breaker please. I googled it but am not sure what I should use.

I'd use 30# roofing felt or you can use a 6mil visqueen.

 

[jomama45]

In 17 years of business for myself, pouring concrete for a living, I've yet to see an existing driveway I would risk pouring directly over. I'd recommend a few inches of gravel buffer in between the 2 at a minimum, but generally speaking, tearing out the original concrete and remediating the failed subgrade is almost always the best decision long-term.............

 

[rranger]

In 17 years of business for myself, pouring concrete for a living, I've yet to see an existing driveway I would risk pouring directly over. I'd recommend a few inches of gravel buffer in between the 2 at a minimum, but generally speaking, tearing out the original concrete and remediating the failed subgrade is almost always the best decision long-term.............

Its more of a cosmetic and drainage issue that Id be repairing. The old concrete is stable and has minimal cracking. I suspect whoever poured the original concrete realized they had done a terrible job in drain planning and tried patching it with the ashphalt which had deteriorated over time leading me to where I'm at with the tearout of the ashphalt layer.