Landscaping: how to stablise clay ?

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xcon

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#232017 26-Mar-2018 08:14

I am looking to prepare the front yard to be landscaped , the end finish is with white stones ideally instead of planting grass

Currently the ground is clay

What is the best way to stablise the clay in preparation for the white stones ?

Thanks

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#1983137 26-Mar-2018 08:33

Why do you need to stabilise it - clay won't move.

I suggest you'd want to put a barrier between the clay and the stones though... maybe a permeable mat to prevent clay silt and weeds coming up through the stones.

Bung

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#1983139 26-Mar-2018 08:40

You'll probably need less white stone if you compact cheap metal as you would if preparing for concrete or tar sealing. Assume that any any potential water problems have been dealt with.

xcon

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#1983147 26-Mar-2018 08:54

Currently clay area gets sloppy when it rains

The area is roughly 7m x 7m

The rain water does not stand as the is a small slope for water run off to the road drain

My fear of dropping white stones straight onto the clay , would the white stones start to sink into the clay when you walking on the stones ?

I was thinking of compacting the metal onto the clay then fill the white stones on top, what grade metal ? GAP20 or GAP40 or....

If I wanted to drive the car on the white stones on the odd occasion , what would be the best approach for the clay preparation ?

Should Geotexile be used ?

Dingbatt

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#1983149 26-Mar-2018 08:57

As above. Clay is massively affected by water, particularly if you are on sloping ground. We made the mistake of insufficient drainage with a driveway, which was eventually undermined.

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timmmay

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#1983159 26-Mar-2018 09:12

I would (have on my lawn) dig trenches, fill with that stone stuff that's maybe 1cm chunks and drainage coil. I put topsoil on top. It went from being a pond in winter to being a nicely draining lawn.

For tiling, that's interesting, I'd ask a professional. I might put in drainage then concrete it before tiles, or at least put in that stone stuff.

1eStar

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#1983180 26-Mar-2018 09:23

Hi. Geotech Engineer here. Without a site appraisal your approach is sounding ok, you should put down a layer of geotextile under the Aggregate. Something like a layer of bidim cloth, followed by a 150mm compacted GAP 40 then your white stones.

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#1983182 26-Mar-2018 09:25

We ended up concreting, but I looked into this a while back. Sort our your drainage issues first, either with metal-filled trenches (don't use standard builder's mix; the sand will just wash away) or with permeable pipe. You'd then need to level it out, ideally using coarser then finer grades of metal and a plate compactor. This will also help the drainage further. If you're using stones and especially if you might end up driving on them, a permeable hex mat will lock everything in place nicely.

Something like this (stocked at Bunnings, I believe): http://www.naturalpaving.co.nz/ There is a youtube video of a two tonne truck driving on this stuff.

All of that is pretty much why we ended up concreting.

xcon

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#1983225 26-Mar-2018 10:23

1eStar: Hi. Geotech Engineer here. Without a site appraisal your approach is sounding ok, you should put down a layer of geotextile under the Aggregate. Something like a layer of bidim cloth, followed by a 150mm compacted GAP 40 then your white stones.

Thanks 1eStar , When you say bidim cloth , would something like this work ? https://www.bunnings.co.nz/cirtex-3-9-x-5m-suretex-geotextile-pack_p00234054

xcon

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#1983228 26-Mar-2018 10:33

mdf:

We ended up concreting, but I looked into this a while back. Sort our your drainage issues first, either with metal-filled trenches (don't use standard builder's mix; the sand will just wash away) or with permeable pipe. You'd then need to level it out, ideally using coarser then finer grades of metal and a plate compactor. This will also help the drainage further. If you're using stones and especially if you might end up driving on them, a permeable hex mat will lock everything in place nicely.

Something like this (stocked at Bunnings, I believe): http://www.naturalpaving.co.nz/ There is a youtube video of a two tonne truck driving on this stuff.

All of that is pretty much why we ended up concreting.

Wow MDF, that looks like a nice product to finish it off :)

xcon

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#1983312 26-Mar-2018 11:23

1eStar: Hi. Geotech Engineer here. Without a site appraisal your approach is sounding ok, you should put down a layer of geotextile under the Aggregate. Something like a layer of bidim cloth, followed by a 150mm compacted GAP 40 then your white stones.

Something this maybe ?

https://www.advancelandscape.co.nz/shop/Erosion+Control+Systems/Bidim+Geotextile.html

neb

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#1983369 26-Mar-2018 12:00

If he's going to be driving on it, what about a pebble stabilising mat over 25/7 scoria? I've got paving stones laid over a massive bed of 25/7 (on top of an infinite depth of yellow clay) and it hasn't moved a millimetre no matter what the amount of rain.

In any case I'd go for the stabilising mat if you're going to be driving over it.

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#1983496 26-Mar-2018 14:39

mdf:

Sort our your drainage issues first, either with metal-filled trenches (don't use standard builder's mix; the sand will just wash away) or with permeable pipe.

If using permeable pipe consider trenches filled with coarse gravel, and/or the pipe you can buy with a textile cover.

Clay is a to drain. As water doesn't move through it very well, the drainage needs to be more closely spaced.

Mike

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#1983560 26-Mar-2018 15:29

Yeah any of those nonwoven cloths will do. As others have said, get your drainage sorted first. The fabric separation provides some strength, but ultimately the thicker you make your aggregagate the stronger it is and the more load it will take without deformation.
I was walking this morning on an area of that naturalpave plastic reinforcement. It appears to have been placed directly on clay, has only experienced foot traffic and has failed dramatically.

neb

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#1983571 26-Mar-2018 15:49

1eStar: Yeah any of those nonwoven cloths will do. As others have said, get your drainage sorted first. The fabric separation provides some strength, but ultimately the thicker you make your aggregagate the stronger it is and the more load it will take without deformation.

Another thing you can do, provided you don't plan to remove the whole lot again in the future, is to put down a base of the aggregate of your choice, run a plate compactor over it, and then lightly dust it with cement before it rains (or sprinkle it with a hose). That'll give you a pretty solid base to lay your drainage fill over, not actual concrete but more substantial than just compacted aggregate. That's how the steps down my garden were done, along with support piles concreted down to the earth's core, and the whole lot hasn't moved despite flooding amounts of rain.

xcon

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#1983968 27-Mar-2018 08:17

Thanks Team :)

Liking the idea/look of the naturalpave plastic

It seems that I will be needing to prep the ground the same if I were to go with white stones for the end result or if I were to end up with naturalpave plastic

Ground prep:

Dig trenchs

Fill trenchs with scoria and drain coil

Lay geotech fabric (bidim cloth) over work area

Build a huge box around work area

Fill huge box with GAP20 and compact over geotech fabric (bidim cloth)

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