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Posted: Wed Oct 09, 2019 8:05 pm
by Djcatfood
Advise needed .. I want to extend my driveway. I dug the footings down 200mm put a textile membrane down and 100mm of grade one and whacked it down. The problem is that it’s on wet clay and it’s spongy. What are my options??
Posted: Thu Oct 10, 2019 8:45 pm
by Djcatfood
I’m going to dig up a section and see how dry it is? if it’s wet is it advisable to add more mot 1 or something larger ie brick rubble underneath?
Any help would be much appreciated 
Posted: Fri Oct 11, 2019 8:03 pm
by Djcatfood
Anyone?
Posted: Sat Oct 12, 2019 11:55 am
by Bob_A
In my experience you will get an answer, they are a very helpful lot on here but they are also busy making a living. Sometimes you get an answer straight away, sometimes you have to wait, just the way it goes
Posted: Sun Oct 13, 2019 10:00 am
by Tony McC
I do try to check the Brew Cabin every day, but sometimes it's just not possible for all of the reasons Bob mentions and a whole host more!
Brick rubble will do nothing but make matters worse. You need to get the sub-base to dry out.
A properly constructed sub-base will rid itself of excess water, either by draining to ground (assuming the sub-grade is suitably permeable), or via buried land-drainage which provides an escape route from the sub-base to some suitable outfall point for those times when conditions are bad. Once the paving is in place, far less surface water will find its way into the sub-base, so it becomes much less of a problem.
For now, find the lowest point within the sub-base area and dig a sump, which is essentially a deepr hole where all the excess water will collect. From that you either bale out or pump out the excess and get rid. It usually needs around 24-48 hrs without heavy rain for a sodden sub-base to drain and firm-up sufficiently to allow paving to be installed.
Posted: Sun Oct 13, 2019 8:45 pm
by Djcatfood
Thankyou so much for the detailed reply and sorry for being impatient I can breath now lol.I had a look underneath the membrane and there is a layer of clay silt underneath. And the mot is sodden wet like you said. A friend offered to bring his mini digger over and scrape the mud out and go to 6 inches of grade one instead of 4.Do you think this is a better option or just leave it to dry out. I was going to chuck some lime in too to speed up the process.
Posted: Mon Oct 14, 2019 7:55 am
by Tony McC
The 'scraping out' and adding more Type 1 will certainly improve matters, but adding lime will lead you towards disaster. A sub-base is intende to be flexible: lime will stiffen it and reduce its long-term effectiveness, so don't do it!
Posted: Mon Oct 14, 2019 4:03 pm
by Djcatfood
Thanks tony your a legend!