I spent about ten hours the other week creating a gabion wall for the first time. I certainly have plenty of learning ahead of me, but I wanted to share some of my experiences thus far.
It’s a tremendous amount of rocks.
We have a shockingly high amount of rocks in our area. You literally can’t sink a shovel more than an inch in our “soil” without hitting granite. Most of our rocks are backpack-sized or smaller, where a sturdy human can move them about. Some are the size of a small car, but that’s a topic for another day.
Amongst other things we’re building a 154 foot long retaining wall that’s 30″ high and 18″ wide. I’m guessing it’s about 500 pounds of rock per foot, which comes out to about 38 tons in total.
Filling them “now” vs using them for unwanted rocks.
If you look on pinterest or other click-baity sites you’ll see some very perfect gabions, some with super elaborate brick stacking. Or perhaps it’s fairly uniform rocks, especially the kind with flat-faced ones up front. If you want to go that route, you’ll need a bunch of empty baskets ready, and then a loader will show up and in goes the material.
If you want surgical looking baskets and uniform fill, that’s the way to go about it.
That’s not really the case with us, where we’re trying to hit multiple birds with one stone.
- First, we need some retaining walls built that look good.
- Second, we have a lot of rocks in roads that pop up from frost heave.
- Third, we have a lot of rocks that are on the sides of the road either from the tractor or the dozer pushing a road clearing.
- Fourth, we want to minimize the amount of materials we bring in, especially ones that have less-than-optimal environmental impacts (ie: concrete).
Unfortunately rocks of all sizes can show up at random times and they belong in different parts of the baskets. So in my case, I have open baskets ready for whatever shows up and an understanding that the retaining wall, and any other gabions, will be filled over time.
These things are super spikey and will rip your clothes, skin, and gloves.
I purchased rather high quality gabion baskets from gabion1, but there’s a lot of snags and sharp points that will grab and do some damage. It’s not the end of the world, but it’s not smoothed timber. In short, don’t wear your nice clothes when working around these. Don’t even wear your nice clothes if you brush up against them. When all is said and done a metal file may need to be carried around for a bit, taking down some of the worst offenders.
To contrast this to railroad ties, they suffer a similar fate. Bathed in creosote and notorious for splinters, you don’t want to brush up against those in your Sunday best.
Rocks are heavy and therefore dangerous.
I have a really cool Gorilla super-duty utility cart with a weight rating of 1,500 pounds. However, imagine having even half of that in a cart that builds up even a small amount of speed and is now aimed at you.
Or, think about how you’re going to get a 70 pound rock into a gabion basket without hitting and therefore destroying the metal on the sides. Never mind leaning over a ~30″ wire edge and tilting, with your back, to set the same stone inside.
However, if you have rocks that you’re trying to clear from your property the mechanics of heavy objects is something you’ll deal with regardless. But give it some thought because while it’s fun to just go ham and work your face off, your body is breakable and you being busted laying on the couch won’t help a project at all.
Future: using these for anchoring.
One place I’m really interested in using this is for anchoring. Typically if you build a structure a goal is to keep that building on the ground and not let it blow away. This is normally handled by foundations and footings, almost entirely via concrete.
Buttressing isn’t done much in timber frame construction but it does still apply to mass-heavy structures like adobe and stone.
I’m pretty interested in trying to tie these things together via gabions. If you can imagine a small outbuilding, with steel horizontal members extending into gabion cages that are buttressed up against the structure: something like that.
They gabion cages are heavy, certainly heavier than most concrete footings. They’re also inspectable, impervious to water, self draining, can be modified once in service, above ground, other gabions can be simply stacked on top, and circumvent many of the shortcomings of concrete.
That’s not to say they’re not without their challenges, primarily (I’m guessing) around the idea that the rocks are loose and can “jiggle” about, potentially. We’ll start with some out buildings (like a solar panel mount) and see how things progress.
Even when they fail, it’s still better than railroad ties.
The vast majority of the work with gabion cages is moving the rocks from their original home and into the wall. Even the very cool Galvan finish of Gabion1’s product will eventually corrode and fail but you know what’s left? The rocks.
Our location is rated C1 since we’re “rural desert”, giving the cages a 100+ year life expectancy. Railroad ties would have turned to dust several times over again in that century, but before they did the retaining wall would have failed, the rebar would have rusted away, and you’d have a pile of materials you would need to discard.
Not so much with the gabion. The steel can be recycled, and even as it rusts that rust isn’t so bad, destroying other environmental pollutants. There’s the environmental impact of creating the steel and galvanizing it in the first place, but something has to function as a retaining wall and I think gabion, if you can handle the look and have available rocks, gets the blue ribbon. Again, compared to timber, those are trees being chopped down, milled, and transported. Nevermind the creosote bath.