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Posted: Tue Jun 26, 2007 7:12 pm
by NickR
I've put 10 tons of Type 1 onto the drive which has run out and am left with about 1m.sq that is short. It has about 10cm of Type 1 already but needs topping up. So would it be OK to put on some spare ballast I have mixed in a 10-1 with cement? The other thing to point out is that the patch is very wet because it is a the bottom of a slope which is why I left it to last. It's drained over the last couple of days (less rain in the south!). Once block paving is on the drainage will be onto the road below and it will dry out fully over time so the ballast and cement maybe no bad thing in the short term. I don't particularly want to buy another ton of Type 1 because I won't use it.
Any thoughts appreciated?!
By the way the drive has been done following Tony's book which is excellent.
Posted: Wed Jun 27, 2007 1:01 am
by slimdotjim
Have you laid the edgings yet?
Posted: Wed Jun 27, 2007 5:01 am
by NickR
Yes the edging is in place and the rest of the area whacked down.
Posted: Wed Jun 27, 2007 10:20 am
by Tony McC
The ballast should be fine. Normally I wouldn't sanction using a cement-bound material within a flexible sub-base, but this just happens to be the one instance when I think it's OK - at the threshold of a driveway.
Because of physics, the stresses imposed on a surface at a boundary are often more significant than those exerted within the body of the pavement. If you look at constructions such as speed ramps, you often notice that the paving has worlked loose at, or close to, the interface between two types of paving/surfacing.
A significant part of this looseness stems from problems with the sub-base, so anything that toughens-up the sub-base at a threshold should be a "good thing" ... within reason. Using, for example, a 150mm slab of 30 Newton concrete in place of flexible sub-base at a threshold would probably not be such a good idea, as it would create a second threshold (this time within the sub-base) beneath the paving and so exacerbate the problem.
However, a square metre or so of weakly-bound all-in ballast should be fine.
Posted: Wed Jun 27, 2007 9:05 pm
by Dave_L
Phew!!! I think that was the reply Nick wanted! 
Posted: Mon Jul 02, 2007 9:54 am
by NickR
Thanks for the advice, I completed the drive over the weekend and the ballast solution worked great. Now I'll just have to complete the finishing off!