Soft Ground
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66-1093879055
We had an extension built on our house last year which gave us a great opportunity to get rid of the broken slabs and blue bricks that had been masquarading as a drive for the last 12 years at least. Once these were removed we found the area infront of our house to be very soft as a result of an old soakaway. The soak away is no longer there and, after much excavation, the ground work contractor capped off the soft area with 1.5 cubic meters of concrete and an amount of Type 1 spread on top. The rest of the drive area had approximately 5t of Type 1 spread on it but has never been compacted. This sub-base has been down for around a year now and seems quite stable and we're faced with the decision of what to do now. We are considering a block paved drive formed with the Marshall's Tegula sett or an imprinted concrete drive. In either case, should we remove all the sub-base, being somewhat unknown in quantity and depth, and start again, or perhaps leave the concrete cap and excavate the remaining drive as per normal for a new installation. Any advice is greatly appreciated.
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84-1093879891
You say that the sub-base is quite stable - is there any sign of "pumping", which is the phenomenon whereby the soft sub-grade material is 'squished-up' through the sub-base by repeated trafficking? The tell-tale indicator is smud on the surface of the sub-base material.
If none is evident, I'd suggest that what you have is worth hanging on to, and the best way to proceed would be to level out what's there now, lay down a decent geo-membrane such as one of the Terrams (1000 is fine) or TDP115, top that off with regulating sub-base material as required to get to formation level, compact the lot and then lay the paving of your choice.
The choice of paving will have an effect on the preparation of the sub-base. If you opt for PIC, you're going to have to bring in a specialist contractor and they should examine the sub-base to determine whether it needs tittivating or replacing, so that they can issue their standard guarantee. However, if you opt for the Drivesett paving and plan to DIY, then the decision regarding the sub-base is yours.
If none is evident, I'd suggest that what you have is worth hanging on to, and the best way to proceed would be to level out what's there now, lay down a decent geo-membrane such as one of the Terrams (1000 is fine) or TDP115, top that off with regulating sub-base material as required to get to formation level, compact the lot and then lay the paving of your choice.
The choice of paving will have an effect on the preparation of the sub-base. If you opt for PIC, you're going to have to bring in a specialist contractor and they should examine the sub-base to determine whether it needs tittivating or replacing, so that they can issue their standard guarantee. However, if you opt for the Drivesett paving and plan to DIY, then the decision regarding the sub-base is yours.
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66-1093879055
Thanks for the advice Tony. It's pretty much what our builder suggested. He employed the groundwork contractor before commencing the build. If we decide to go for the Drivesett we'll be employing a contractor to do the job. I guess they may want to excavate the sub-base again to comly with the Marshall's guarantee. Have you any recommendations for a contractor in the Warwickshire area? Those we've contacted so far (listed in the Marshall's approved register) have not been too inspiring.
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66-1093879055
CV12. E-mail sent
Edited - I had to remove my email address from your post otherwise the spambots would harvest it and one of the few spam-free addresses I have would be tainted.
A word of advice to you and every other iuser of this site - don't ever, ever post your own or anyone else's email address to any website unless you want to be inundated with spam. Inadvertent or naive posting of email addresses to websites is one of the major sources of valid addresses for the spammers.
I go to a lot of trouble to protect email addresses on this site. None of the addresses used to post to this forum can be harvested by spambots, and the few places where my own email address appears, it is protected by a piece of code that renders it illegible to non-human readers.
Spam is the curse of the internet - don't make it any easier for them to continue their nasty, selfish, corrupt trade.
Tony McCormack
Edited - I had to remove my email address from your post otherwise the spambots would harvest it and one of the few spam-free addresses I have would be tainted.
A word of advice to you and every other iuser of this site - don't ever, ever post your own or anyone else's email address to any website unless you want to be inundated with spam. Inadvertent or naive posting of email addresses to websites is one of the major sources of valid addresses for the spammers.
I go to a lot of trouble to protect email addresses on this site. None of the addresses used to post to this forum can be harvested by spambots, and the few places where my own email address appears, it is protected by a piece of code that renders it illegible to non-human readers.
Spam is the curse of the internet - don't make it any easier for them to continue their nasty, selfish, corrupt trade.
Tony McCormack
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84-1093879891
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66-1093879055
Hi Tony,
Thanks for your recommendations but I'm yet to decide who to engage as contractor for my drive. On a friends recommendation, I've just spoken with a local contractor who raised a couple of interesting points:
1. All domestic paving blocks will be manufactured in 50mm thickness to conform to a new BS. Know anything about this?
2. The concrete area I mentioned in my first posting will need to be removed and the ground excavated to get rid of the soft area, possibly with the addition of a membrane for stability, although I tend to agree with your comment that what we have is worth hanging on to. His reason for removing the concrete area is he will not be able to compact the blocks properly on top of it. Any thoughts?
Cheers
Mark Patrick
Warwickshire
Thanks for your recommendations but I'm yet to decide who to engage as contractor for my drive. On a friends recommendation, I've just spoken with a local contractor who raised a couple of interesting points:
1. All domestic paving blocks will be manufactured in 50mm thickness to conform to a new BS. Know anything about this?
2. The concrete area I mentioned in my first posting will need to be removed and the ground excavated to get rid of the soft area, possibly with the addition of a membrane for stability, although I tend to agree with your comment that what we have is worth hanging on to. His reason for removing the concrete area is he will not be able to compact the blocks properly on top of it. Any thoughts?
Cheers
Mark Patrick
Warwickshire
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84-1093879891
A colleague who works for one of the largest manufacturers in the UK told me some time ago that there were mutterings about bringing 50mm 'driveway' blocks within the scope of BS6717, but whether they ever will, I can't say. My understanding was that there were 'issues' with the tensile strength of 50mm blocks and making them strong enough to meet the test requirements would eliminate any cost saving made by reducing block thikness from 60mm to 50mm.
I can't see them introducing a wholly new BS purely for driveway blocks, so BS6717 would need to be amended, I suppose, but then, we are supposed to be moving towards a pan-European standard, and 50mm blocks are uncommon on the continent. To be honest, I don't think bringing 50mm blocks within the scope of a British or European Standard is all that important, but I'll ask around and see if anyone else is aware of this.
Turning to the issue of re-using the concrete base, laying block pavers over a concrete base is an accepted and approved methodology. If your contractor has a problem compacting blocks laid over a concrete base, it suggests their skills and experience are more limited than should be expected.
I can't see them introducing a wholly new BS purely for driveway blocks, so BS6717 would need to be amended, I suppose, but then, we are supposed to be moving towards a pan-European standard, and 50mm blocks are uncommon on the continent. To be honest, I don't think bringing 50mm blocks within the scope of a British or European Standard is all that important, but I'll ask around and see if anyone else is aware of this.
Turning to the issue of re-using the concrete base, laying block pavers over a concrete base is an accepted and approved methodology. If your contractor has a problem compacting blocks laid over a concrete base, it suggests their skills and experience are more limited than should be expected.