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Posted: Mon Mar 23, 2009 4:53 pm
by loudog
Hi to everyone, Quick question, I have to block pave a 70sqm drive for a client, drive is currently tarmac. When i take up the tarmac, do i need to bother with the Geotex or can i lay my grit sand straight on top the original scalpings. Thanks for any help.
Posted: Mon Mar 23, 2009 5:20 pm
by msh paving
First thing is you need to find out the falls for drainage,
60mm for block, 40mm compacted grit sand,100-150mm mot type 1 sub-base so will the existing be deep enough? do some trial holes to find the scalping depth and work out if it will work out deep enough,
when you say geotex are you talking about geotextile such as terram or lotrax? there is no need for terram under the laying sand as long as it a close texture base
http://www.pavingexpert.com/screeding.htm#screed
MSH 
Posted: Mon Mar 23, 2009 5:29 pm
by loudog
Thanks Msh, yeah when i remove tarmac will have to see what depth i have for blocks and grit sand to go on, just wanted to know that when i remove tarmac and there is enough depth is there any need for Geotex, as extra work to remove type 1 and then lay Geotex and put type one back again, but if thats what has to be done then that is what will happen, Thanks for your reply.
Posted: Mon Mar 23, 2009 7:38 pm
by GB_Groundworks
your taking a chance using the existing subbase unless your are sure its perfectly sound and sufficient depth. if it goes wrong and your blocks sink then its down to you, i'd be relaying it all.
Posted: Mon Mar 23, 2009 8:16 pm
by Tony McC
Ask yourself what function this "Geotex" would perform if you lay it where proposed.
Posted: Mon Mar 23, 2009 9:05 pm
by loudog
Well i guess it seperates the type one going into the soil, the truth is the guy called me in to tarmac the drive about 6 years ago, he layed all the type one and the drive is totally sound, no sinking, but if your advise would be to take it up and start again then that is what i shall do, many thanks for your replys
Posted: Tue Mar 24, 2009 8:12 am
by Mikey_C
Having re read your original post you were implying that you planned to put the geo-textile in between the the existing subase and the grit sand bedding layer, which is pointless. Others were concerned that you were staking your reputation on an unknown/unproven subase. As you have now eluded to the fact that the subase has pedigree and was also laid by the customer chances are it will be fine and does not need ripping up just to have the geo-textile installed. However, leaving the subase should be discussed with the customer and then should be detailed in your quote/invoice/guarantee as not you liability.
Regards.
Posted: Tue Mar 24, 2009 10:23 am
by Tony McC
loudog wrote:Well i guess it seperates the type one going into the soil
As Mikey-C says, you plan to re-use the existing sub-base, so how would you get the "Geotex" into position between the Type 1 and the sub-grade (what you refer to as 'soil')?
Posted: Wed Mar 25, 2009 5:19 pm
by loudog
well i would excavate the whole lot to the correct depth and lay the Geotex and then the type one on top, basically start from scratch