Gabion fill

[mangers]

Hello,

 

Need to create a gabion retaining wall, circa 30m in length, 1m in depth and 1m, 1.5m, and 2m high stepped in various places. The question I have concerns the gabion fill. Everywhere I look I see that gabion fill stone should be angled and range from 100mm-200mm for your typical mesh aperture 76mm (3 inch). Where I'm living, getting that size stone costs about 150 quid a jumbo bag. I'd need about 50 bags! Dump truck from quarry is not an option unfortunately. Have no access to rubble either in case anyone asks ?

 

The front of the gabions aren't public facing at all. I was thinking of stacking concrete soap bars 440mm x 140mm x 100mm to the front of each gabion and the 2 sides at either end of wall. I'd have a 10mm gap between each soap bar for drainage. As the soap bars are acting as a barrier, theoretically it could allow me fill baskets then with much smaller and cheaper drainage stone or even 12mm decorative stone (25 quid a jumbo bag). Huge saving!

 

Each m3 will be braced at the usual 1/3 and 2/3 front-and-back (4) and at least 1 brace left-to-right. So 5 braces per m3 at least. Gabion wire will be 3mm except the front which will be 4mm.

 

Would it work? I understand the larger angled stone will lock thus preventing bulging, but hoping the lovely flat surface of the soap bar and bracing would work equally as well.

[markc]

Gabions are fantastic and dangerous at the same time. You are correct in that they need large angular fill in order to interlock and become stable. Using very small free moving material behind the face can cause catastrophic landslide situations if and when the gaboon fails. The gaboon itself should be considered a building guide as opposed to a structural component. Do you have any possibility of demolition brick / concrete infill?

I have seen some fantastic retaining/feature gaboon walls done with concrete.

[nod]

When we installed our Gabions We found similar prices for stone 

Going directly to the quarry for loose 20 ton load worked out about £30 per ton delivered 

[markc]

Gabion not gaboon. Stupid auto correct ?

[Haylingbilly]

If the front of the Gabions aren't visible, why are you using gabions? Could you not use another solution?

150 bulk bags of material is a lot to move - I take it you can use machinery for it otherwise will be very time consuming to manhandle?

 

 

[mangers]

4 hours ago, markc said:

when the gaboon fails

Gaboon in this scenario sounds about right ?

I never considered a failed gabion and the ramifications that could follow. Point taken. Smaller stone would have much more difficulty holding back a landslide should the gabion fail in comparison to larger heavier stone. In fact it would be useless. Thanks for pointing that out.

I ventured to the local quarry early this morning. I knew a 20 ton tipper lorry delivering all that stone on my relatively small driveway wouldn't go down well my neighbours... and come to think of it my wife. Moving all that by hand would take many weekends just to clear the driveway! Turns out the quarry put me in touch with a local lad who does 5 ton deliveries. Obviously he'll charge his own delivery rate. What really surprised me though was the price of stone. They had 6inch clean limestone for collection at about 9 pounds per ton. That works out at 360 pounds for 40 ton! Plus the surcharge for delivery from the local lad which I've yet to find out. 

It's looking like batches of 5 ton a go might work out very well.

I am though getting mixed comments about the suitability of limestone for gabions. Is it OK or should I be looking for sandstone or granite?

 

[mangers]

50 minutes ago, Andy brown said:

Could you not use another solution?

Every thing needs to brought in from front to back. Zero direct access in the back. Concrete lego blocks would be perfect but they'd break my back carrying them in from the front.  ?
In addition to retaining wall, the 2m high gabions will allow me to level out the garden with back fill. Had thought of raised decking but i'd still need something to retain the bank. Here's a picture from a few weeks ago... have since dug/pickaxed more since. 

I honestly don't mind the carrying of stone from front to back, wheelbarrow at a time. I could spend 1 hour in the gym or get a great weekend workout this way.

 

[Haylingbilly]

I had 10 tonnes to shift about 30meters distance but 5m incline. My structural engineer recommended a lightweight solution as was worried about the weight of gabions on the back of the house. Thank god he did, the lightweight solution nearly broke me!

 

Do you even need a retaining wall there - looks like it is for landscaping and is the bank stable enough as it is? If you do a sleeper wall would be so much easier to move - probably 100kg of material to move per linear meter vs 3 tonnes!

 

I really would test moving a tonne of stone before you commit to moving 300 odd tonnes. That is a massive undertaking, really is. I had the same view as you regarding an alternative to the Gym but my solution ended up being a tonne but it was still no laughing matter!

[mangers]

2 minutes ago, Andy brown said:

moving 300 odd tonnes

Well that would kill me, I only need (only says he) about 40t. I was thinking of making a small investment in one of these if the going gets too tough... it'll squeeze nicely down the side of house to the back.

That bank you see in picture has been like that since I tackled it in our first lockdown. Hasn't budged. Not to say it won't budge. It might some day. Not a gamble I'm willing to take.  Not even with a sleeper retaining wall. I'd just feel happier with something a bit more solid and weighty down there.

One option is to just retain this bank with 1m3 of retaining gabion. Then instead of going another 1m course higher in gabion,  just have a raised decking to level garden. Anyway, this digresses from main thread title. I'll start another thread on that if I get that far.

[Dave Jones]

if the gabions need facing you can buy them with an inner mesh that holds 100mm of gabion stone, the rest behind it you can fill with anything that wont fall through the mesh that is clean, ie no dust.

[mangers]

56 minutes ago, Dave Jones said:

if the gabions need facing

...they don't in my case. Anything goes, as long as it's cheap and structurally sound.

Got call back from delivery guy... here's break down so far:

40t clean limestone (150mm) @ £9 per t = £360
£40 delivery for every 5 ton, 8 deliveries   = £320
Total delivered                                               = £680 (inc. vat)
- works out at £17/t delivered.

All I need to know now is if (clean) limestone is suitable and if it is I think I got myself a bargain considering I can get it delivered incrementally like above in 5 ton batches.

Edited September 29, 2021 by mangers

[Cpd]

1 hour ago, Andy brown said:

Do you even need a retaining wall there - looks like it is for landscaping and is the bank stable enough as it is?

I would second this, it looks like where you have already cut the bank back it’s already greening up which is a good sign it’s fairly stable, obviously I can’t see in detail but the solution your looking at seems a bit over the top. I have a very similar bank I cut back 10 years ago with the information of putting gabions in and it’s still not done and still not fallen down and it’s right behind my house ! I am just put of by the cost of the actual gabions….. and I cannot get more than 2 tons of stone at a time. I have still not come up with a cheap solution so can’t help on that front but I have moved hundreds if not thousands  of tons of stone by hand over my life (stonemason) and it’s really a pig of a job when it’s a situation like your explaining. Just make sure you really do need to (or really want to) go down the gabion solution before committing! For another job I made my own out of fencing wire ! The volume of stone it took was catastrophic but it had up to 1m behind it fully filled with stone as well. 

[markc]

Got to agree with the above, gabions (still trying to auto correct) are intended in place of cast in situ walls/abutments or sheet piling etc.

if the bank is well established then the root systems will hold it

Edited September 29, 2021 by markc

[Mr Punter]

You may be able to use some sort of geomesh system to prevent erosion and stabilise the bank.

[saveasteading]

17 minutes ago, Mr Punter said:

geomesh system to prevent erosion and stabilise the bank.

 

1. The simple solution if it appears reasonably stable.

2. Build a block wall with hollow blocks and reinforcement up through it, and put drain holes through it

(or a special block as below right if you so choose.

It is possible to tie the wall back into the hillside with anchors (platipus) and cables. i saw them in a fencing shop even.

Backfill with rubble, as loose as you like (not gravel as it will move if the bank does)

 

what is the worst if the bank slipped significantly? What is on and above it?

 

 

 

 

[mangers]

Thanks everyone for your feedback. Food for thought. Here's another angle. The bottom of trench is around 4m below the house level and 8m horizontally away from the house. Gabions was my preferred option as 
1. Solid
2. I wanted to extend and raise the back of garden up by 2 metres and back fill with soil. Though 2m won't level the garden it would make a huge difference.

 

[Cpd]

This picture put it into context, gabions will be perfect ! 
pictures speak a thousand words and all that…..

[Haylingbilly]

36 minutes ago, Cpd said:

This picture put it into context, gabions will be perfect ! 
pictures speak a thousand words and all that…..

Doesn't it just? Now it makes sense...

Gabions would work but I would not underestimate how hard it will be to move 50 tonnes by hand

I would look at Criblock Retaining Walls - @mangersyou have the perfect space for them.

 

[saveasteading]

Rubble is usually free if you can collect it, and if you have trailer and towbar.

[Bramco]

5 hours ago, Dave Jones said:

the rest behind it you can fill with anything

 

indeed - ours are filled with old bricks, set so they are interlaced as much as possible and therefore very stable - and a lot cheaper than filling the backs of the gambions (as they are known in our house) with expansive stone.   Mind you, you need a source of cheap old bricks....

 

Simon

[mangers]

CPD and Andy. Thanks for the gabion reassurance. Thought I figured it out all wrong. Andy, those criblocks look really interesting. The tiny bit I read I think I'd nearly prefer them than the gabion solution. Looking forward to a quiet house later once everyone is in bed to do further research and costs.

1 hour ago, Bramco said:

expansive stone

If I could source rubble or demolition brick I would, though I thought 40t of stone delivered for £680 was a decent price.

 

Plans might all change if those criblocks are cost effective.

 

Thanks folks.

[Dave Jones]

7 hours ago, mangers said:

...they don't in my case. Anything goes, as long as it's cheap and structurally sound.

Got call back from delivery guy... here's break down so far:

40t clean limestone (150mm) @ £9 per t = £360
£40 delivery for every 5 ton, 8 deliveries   = £320
Total delivered                                               = £680 (inc. vat)
- works out at £17/t delivered.

All I need to know now is if (clean) limestone is suitable and if it is I think I got myself a bargain considering I can get it delivered incrementally like above in 5 ton batches.

 

well if its not seen, then i would use 75mm-150mm mixed clean. will be easier to fill. Also the 3mm gabions tend to bulge easily the 5mm are much better. Dont forget to put the tensioner wire in the middle when half filled.

[Dave Jones]

1 hour ago, mangers said:

CPD and Andy. Thanks for the gabion reassurance. Thought I figured it out all wrong. Andy, those criblocks look really interesting. The tiny bit I read I think I'd nearly prefer them than the gabion solution. Looking forward to a quiet house later once everyone is in bed to do further research and costs.

If I could source rubble or demolition brick I would, though I thought 40t of stone delivered for £680 was a decent price.

 

Plans might all change if those criblocks are cost effective.

 

Thanks folks.

 

£680 for 40 ton is not too bad, its 2 loads on an 8 wheeler. 

[CotswoldDoItUpper]

Justly throw another idea out there…. What about using something like ICF and rebar? 
 

no idea if it would work, or what an SE would say, but lightweight to carry and you can pump the concrete in? Prob more expensive, but might be less back breaking!! 

[Dave Jones]

could use concrete lego blocks but they need kit to install along with drainage and are expensive compared to stone and wire.