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Posted: Mon Sep 17, 2012 5:04 pm
by oldboy
Firstly, let me say how helpful this site has been. I first started looking a few months ago to get some pointers as to what I should be looking for when getting someone round to look at repairing my drive but it now seems that I am going to be doing the job myself, but I want to run my thoughts past you experts and I also have some questions.

Part of our driveway is sinking. Information from the neighbours suggests the blocks were laid and part left as lawn. At a later date the lawn was lifted and block paved to join up with our existing blocks and the neighbours blocks. The part that is sinking is where the lawn was.

I have lifted some blocks to make a ‘test pit’ at a few places and find nothing but clay like earth underneath. So the plan is:

Lift the blocks on the strip – about 25m x 2m - and clean the blocks. I expect this to be a time consuming part of the job otherwise there will be problems when I come to lay them again, so any tips for the cleaning apart from ‘elbow grease’? I thought on using a wallpaper scrapper and hard bristled brush. Would a wire brush be ok?

Excavate to a depth of 230ish mm to allow for 150ish mm sub base, 35-40mm sand and then 50 mm for the block. Hopefully the blocks should be sitting 5 mm proud before compaction.
Is my sub base enough to take the weight of a 3 ton truck?
Is sitting 5mm proud enough/too much?
Should I do the 150mm in one compaction or in two lots of 75mm each?
Is there anything that I need to be watching out for at the edge that joins with my neighbour?

Use a geotextile under the base for separation purposes. I have looked at Terram 1000. Am I looking at the right thing? If so, the sites I have looked at seem to sell 100m rolls. Any ideas where I can buy the length I need rather than 100m?

Compacting down to match the level of the remaining block I understand from the web site is a case of trial and error. So what size of area should I use as my ‘trial’ and does that include using the jointing sand and then compacting?

I’m sure I’ll have more questions but I want to know if I’m on the right track so far. Any advice appreciated. Thanks.

Posted: Mon Sep 17, 2012 6:45 pm
by Carberry
Pressure wash the blocks whilst they are down, then lift them, rather than trying to wash each one by hand as you lift them.

Buy the 100m roll of terram, by the time you overlap it over 50m2 you will have used most of it.

150mm compacted in 2x75mm layers. That will be fine for 3T assuming the ground below that is fine. If the ground below it is soft dig down further.

Lay free edges on concrete and haunch.

Posted: Mon Sep 17, 2012 9:22 pm
by lutonlagerlout
Carberry wrote:Pressure wash the blocks whilst they are down, then lift them, rather than trying to wash each one by hand as you lift them.

Buy the 100m roll of terram, by the time you overlap it over 50m2 you will have used most of it.

150mm compacted in 2x75mm layers. That will be fine for 3T assuming the ground below that is fine. If the ground below it is soft dig down further.

Lay free edges on concrete and haunch.
pressure washing wont clean the sides of the blocks
just pick them up and clean them with a stiff scrubbing brush

also i dont like haunching,kerbs or edgings are a far better job
plus bear in mind that you are duty bound to install a linear drain to a suitable soakaway under the 2008 SUDS regulations
We do,many dont
all the best LLL

Posted: Tue Sep 18, 2012 6:04 pm
by oldboy
Thanks for the info. Need to read up on the SUD section now.