Cracked concrete drive - Pave over or dig out?

[DaveJ]

Afternoon all

I have a concrete drive which is cracked and needs replacing. It slopes up towards the house at about 1 in 5 and appears to be about 150 mm thick. There is also a concrete path along the front of the house which looks about 200 mm thick. All together there is about 25 square metres of concrete to be replaced.

I have looked through the Brew Cabin topics (honest) but can't find one to match my particular questions.

Plan A was to dig up the lot and start from scratch, but looking through your site, I realised that I could pave over existing concrete. I could put in a transition ramp at the bottom and there is enough space below the DPC at the top. Sounds good, means digging out about a quarter of the concrete.

I've got two questions. Firstly, the concrete is cracked. It's
broken into 3 slabs, all of which are about 3 X 2 m, which have settled vertically (by a few mm), as well as parting horizontally. It hasn't got noticeably worse in the 8 years we've been here.

Would you recommend paving over it?

If the answer is no, you can ignore the second question.
If I widen the drive on a DTP sub-base, is it likely to settle more than the section on the 50 year old concrete? Would you recommend laying new concrete on either side of the old stuff, and then paving over the lot?

I've got a few photo's if anyone can tell me how to attach them

[Paverman Dan]

Just my opinion, no on paving over the concrete. I know the slabs have not migrated over the past 8 years, but eventually they will, and any future movement would be reflected in the top of the pavement.

It is ok to overlay on concrete, but it must be in good condition, and your description gives me the jitters.

[DaveJ]

Thanks Dan Looks like I'll have to go back to Plan A

Cheers

[Tony McC]

I'm not a big fan of paving over concrete, ctacked or otherwise, but I think the decision has to be yours. Although you may not have observed any movement/settlement during your residency, there may have been some that you didn't notice because you're accustomed to seeing the existing driveway every day.

However, having said that, if there has been movement, it must have been slight otherwise you would have noticed, so you might decide it's worth 'risking it' and paving over the concrete in the hope that any further movement is slight or non-existent. One of the pluses for block paving is that it is better able to accommodate slight movement than is the case with a rigid pavement, and, even if there was some significant disturbance, sufficient to create a trip hazard, for example, then lifting a section of the paving and re-laying it to eliminate the trip is no major task.

To be honest, without seeing the existing, I can't say whether I'd pave over or start from scratch, but the thought of breaking out all that concrete when it might not be essential does urge me to give more consideration to paving over.

If you do decide to pave over, the extended areas could use either a concrete (rigid) or a crushed stone (flexible) sub-base: there is likely to be some movement at the boundary which ever you choose. Rigid concrete may well move in sympathy with the pre-existing concrete slab, while flexible crushed stone is more likely to suffer from a degree of differential settlement. But, as mentioned in a previous paragraph, neither is the end of the world and can usually be fixed in a couple of hours.

[DaveJ]

I'm not a big fan of paving over concrete, ctacked or otherwise, but I think the decision has to be yours. Although you may not have observed any movement/settlement during your residency, there may have been some that you didn't notice because you're accustomed to seeing the existing driveway every day.

However, having said that, if there has been movement, it must have been slight otherwise you would have noticed, so you might decide it's worth 'risking it' and paving over the concrete in the hope that any further movement is slight or non-existent. One of the pluses for block paving is that it is better able to accommodate slight movement than is the case with a rigid pavement, and, even if there was some significant disturbance, sufficient to create a trip hazard, for example, then lifting a section of the paving and re-laying it to eliminate the trip is no major task.

To be honest, without seeing the existing, I can't say whether I'd pave over or start from scratch, but the thought of breaking out all that concrete when it might not be essential does urge me to give more consideration to paving over.

If you do decide to pave over, the extended areas could use either a concrete (rigid) or a crushed stone (flexible) sub-base: there is likely to be some movement at the boundary which ever you choose. Rigid concrete may well move in sympathy with the pre-existing concrete slab, while flexible crushed stone is more likely to suffer from a degree of differential settlement. But, as mentioned in a previous paragraph, neither is the end of the world and can usually be fixed in a couple of hours.

Thanks for the advice Tony. I've broken out a bit of the existing concrete and it's not as hard as I expected. Since the inclined part of the drive is cracked into three blocks, if I removed a couple of yards at the bottom to put in a transition ramp, the top sections would be more likely to move down the slope. Add to this the fact that there might be a difference in settlement between the flexible and rigid sections and that I only want to do this once, I'll go for a fresh start and remove the lot.

Cheers

Dave Johnson

[danensis]

This is where you need a queue of crusher renters at your door, who will recycle all that concrete into DTP1 for you.