I was recently on a site where a low retaining wall had been built from what appeared to be filled ready-mix bags. The paper had been cut away after the wall was dry and in place. This installation is at least ten years old and is in very good shape. Of course no one knows who built it.
I would like to use this technique, but maybe add some color to the mix. Does anyone have ideas on how this might have been accomplished?
Perhaps sand bags were filled with the ready-mix?
And would you need to wet the wall down after stacking the layers to improve hydration of the concrete?
Replies
I'd not speculate how that wall might have been accomplished if it actually holds back any soil presure, but I have seen short walls done the same way you describe. It looks like Sakcrete bags just got stacked up against the embankment with a bit of a backset to each course and let time and weather take care of the hydration. Who knows? Maybe they were hosed down.
Kinda scary to think that there is any real retention happening there -- probably decorative (?) erosion control more than anything.
Anyway, as far as color goes, I wouldn't add anything to the mix. Way too much work. The whole idea of this technique is you are just stacking bags, so it's cheap and easy.
You could, however, use Lithochrome or any of the many similar acid/iron salt based chemical stains. They're easy to use, and the ones I've used are supposed to be (according to my distributor) actually beneficial to the soil after it has been reacted and diluted.
DRC
More expensive than block, but easier, and probably stronger.
Stack the plain old bags in just the way you describe. With an offset to each row.
Along the way, drive 3 or 4 foot long pieces of rebar through the sacks. Into the ground at first, then through a couple bags at a time, into the ground.
Mother nature will take care of hydration, setting up, curing.... and eroding away the cardboard bags. If you buy the kind with the plastic in the bag, you'll have to either cut the bags away once everything has set up, or you have to wait longer for the sun to biodegrade the plastic they use.
With the rebar driven through them, often enough, the wall is no less strong than one set up out of blocks with rebar/mortar fill of a cavity, every so often. Maybe stronger, because each bag of crete will conform itself to it's surroundings and 'cast' that way. And because of the width of the bags, a wider wall results as well.
Even after the rebar rusts away in the ground, and starts to rust up into the 'blocks', the whole thing is going to stay interlocked. If the wall is built with the same attention to physical laws as any other retaining wall is, it will last longer than any of our lifetimes.
This is my own real-life experience. Call it an opinion if you wish, and find all the ways that it is wrong, according to code. But it still works in real life. And it works well.
This also works well for those short walls at the ends of a culvert in a driveway.
Quittin' Time
I'd say you're onto something there, Luka. What about an arch with a temporary center that you remove after the concrete hardens?
Buying concrete by the sack like that is pretty expensive though. What is a 60 lb sack, .44 cubic feet or something? 90 pounders are .66, aren't they? Even on sale that's pretty expensive for anything large.
But I can't imagine anything much easier for building a retaining wall. Gravel behind the wall and weep holes, like maybe some short pieces of 1" ABS, through the base of the wall, right?
Geez, now I have visions of retaining walls and arches all over the danged yard. Might have to dig a moat and built an arched bridge in the driveway (easier to defend, better lines of fire).
Brinkmann for president in '04
I saw a retaining wall once that was done like that, only using burlap bags. It was an ultra quick job, done during WWII for a shore gun. It would have been about 25 years old when I saw it, and it was holding up just fine. A house was built over that site and later torn down for airport expansion, so there's a chance that the wall is still there after 60 years.
-- J.S.
Thanks,
This is the type of encouragement I needed. What do you think the set-up time would be? How long before you would remove the bags?
OK, I'll scratch to color.
sparks
In La Jolla, CA (part of San Diego despite what the La Jollian's say) there is a house on the coast with a sea/retaining wall built like that. It is between PB Point and Bird Rock (just north of Hennaman's if you know the surf break). Anyway, it is quite an extensive structure, maybe 50' wide and sloped up the bluff maybe 12' to 15'. It's been there a long time and undoubtably sees some heavy abuse (like last Thanksgiving when the surf was so big almost no one went out anywhere in the county, and I did not see anyone in the LJ Reefs area).
Scott Owen
One year to full setup and cure. If you build it, then let it set with no other interference.
Get it built before the end of summer. The winter rains should hydrate it.
You don't want to oversoak it, but you can go out and spray it with water every once in a while, if you wish.
Leave the paper to degrade naturaly, for at least a full year. By that time, the 'blocks' should be cured well enough not to crumble when the paper and plastic is cut away.
I was given about 12 bags that had already begun to set up. They had been exposed to the weather for 2-4 months already. I put them all in as part of the retaining wall at the end of a culvert. Before the end of summer. By spring, they were all set, and the paper had begun to decay. It took about a year for the paper to really start to come away, and by that time, the 'blocks were solid as any rock.
What I really liked about this was the fact that since the area they were going into was very irregular, (parts shaped like a strong "V")... I just tossed the bag where I wanted it, then stomped and jumped on it to conform it to the place I wanted it to stay in. Ended up with solid blocks that were perfectly shaped to their surroundings. And locked into each other. No cutting of concrete blocks or bricks, or rock. No mortar to worry about. No form to build. Etc.
Yes, it takes patience. Just like growing hair. You may not like how it looks in the meantime, but when it is finished, you will be glad you waited.
I really kind of like the looks of a retaining wall built this way.
Quittin' Time
Sounds like a new franchise coming along...
LUKAWALLS'R'US
or would that be, 'Lookawalrus' pronunciation?
Excellence is its own reward!
I am.
Koo koo kachoo.Quittin' Time
So was it Sgt Pepper who built that wall originally?
No wonder it was leaning comfortably!
LOLExcellence is its own reward!