Building a retaining wall in the conventional ways (above) is not a trivial matter. So DIYers have come up with an interesting trick: Rather than messing around with mortar, they lay the walls down like Lego pieces, using concrete while it's still in the bag.
That's right, the idea is that you don't open the packaging. Once the bags are laid, you wet everything down thoroughly with a hose, saturating all of the bags.
Once the concrete sets up, you can either wait for the paper to biodegrade, peel it off, or burn it off.
Prior to wetting the concrete, you can easily drive rebar into the bags as reinforcement.
You can also use the technique to build sunken fire pits.
Once cured, you can tell that these were made using bags, but I don't find the effect unpleasing.
If you want to use "bricks" that are smaller in size than your standard concrete bags, you can put in some extra work and re-bag the concrete in smaller lunch bags. That's what the fellow below did to create a retaining wall, and even a short series of steps, to brick in this culvert:
I wonder if, as in the entry about fenceposts, you can simply wait for a thunderstorm and forgo the hose step.
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The last photo, right above the video, shows evidence for what I was trying to point out in my prior comment. You can see how weak the wetted bagged concrete is; its surface is flaking off. This is evidence of the concrete not curing correctly due to an incortect ratio of water to cement and lack of mixing. As I said before, you can't just hope that the water will wick through the cement correctly. The cement actually needs to be mixed thoroughly so that all of the minerals that need to be hydrated get properly hydrated at the correct level.
The Pantheon in Rome is all I have to say. Free standing poured concrete non reinforced dome. 18 centuries old.
It's entirely possible to build a retaining wall without reinforcing the concrete (though not advised as the reinforcing will allow you to use less material), so long as the concrete always works in compression, this is how the first concrete dams were built or indeed many roman buildings.
But, and this is the crutial point made by David and Austin, the Romans were only able to use concrete without reinforcing because they understood the chemical properties of the volcanic ash they used to make their concrete and the proportions of water and aggregate to allow it to solidify and last milliennia!
They most definitly did not pill it up in bags, through some buckets of water at it and hope for the best !!!
This is method is ignorant of how cement works. I just listened to an audiobook called "Stuff Matters" by Mark Miadownik, about the material science behind all the common materials that make our modern world—paper, concrete, steel, etc. and in it, the author explained that concrete doesn't dry when it hardens; it actually cures in a reaction with water such that it incorporates water at a precise ratio in order to become strong concrete. An incorrect ratio of water, whether too much or toot little, results in weak concrete. The water needs to be mixed into the concrete; you can't just hope for it to percolate through, otherwise you get the worst of both—too much water on the outside, insufficient water on the inside.
yooooo that's a good read
My Father-in-law told me that, back in the day in Italy, they used to build piers by putting concrete in plastic bags and placing them under water.
They did, for Freshwater and Saltwater, but do realize that in Saltwater Applications the Plastic Density to Porosity applications, works a Desalination, and that plastic Bag is usually in place per Layer, only until it Sets, not: Stacked Upon, 6 layers High, as this Crazy Collage Suggest. Which if you spray WD40 between these Photographed Installs, you got slippy slidey Blocks, that Fall on Toes and Feet and Infant Heads. Are these gonna pay for Security Personnel to Look out for those Dreaded Vandals with WD40? No. You'd be Better off Tapping a 39 cent Funnel or 6 inch of a Dowel in Each of the Bags, maybe with a Rubber Mallot Made of Duct Tape according to Directions from a Myth-busters episode than to 'Stack 'em as you buy 'em' as this crazy collage suggests...
I laughing at seismic catastrophe comment. if you're going to California and see what people stack one highway on top of another an earthquake zone is pewter freaking catastrophe and asinine as hell. Show me retaining wall that won't come down have an earthquake. Dumbest comment ever.
Sorry for the typos. Voice typing is below par.
This is a great technique for inexpensive landscape walls of finite lifespan. The criticisms that the concrete isn't wetted ideally are misguided. These are just simple gravity walls, basically the same as dry stacked blocks. The strength of the concrete is largely immaterial. Sure, there'll be some degradation like pointed out in one photo, but that's cosmetic and has little effect on performance. This is not the way to build a wall that you want 100 year life out of, but for more modest applications, it's a perfectly viable technique.
In Bulgaria we have one wisdom: “ Give the lazy man job, he’il give you brain”.
Great saying. I have Seen that inactivity in inaction.
You are not gonna get very strong concrete this way. Not that it matters too much for retaining g wall (which doesn’t require any where near the strength of a foundation). But your retaining wall made this way is not going to last anywhere near as long as if you do it the correct way. And really, how much time are you saving this way? Not very much.
Seems like there might be an opportunity to design a concrete package that is meant to do this.
Have you never heard of Corrugated Cardboard? Effect is Same, in 20 years or less, the Projection is, they who Look at the Expense of Doing this Twice Poorly, rather than Once Properly, end up saying: 'Next Time, we May as Well Pour Stepping Stones in Tupperware'.
Quikrete and Sakrete already do, among others. The third photo (the two-tiered wall) is actually from Sakrete's promo material.
Interesting, but I'm not sold. One thing I noticed about all of these is that none of them have a gravel footing or any drainage behind the wall. The one exception would be the terraced one (4th image down), but that one will probably fail as well since they didn't allow enough spacing between the 2 walls which multiplies the load on the lower wall.
I'm starting to think I should use this method for my biz at Retaining Walls Dallas. I'm just not sure if it's a long-lasting approach? Let me know, thanks!
I've never seen this before, but it's pretty genius. I'm kinda surprised by this retaining wall approach but you're right, even though it looks like bags it's not too bad. Besides, it seems way easier to stack. But I do have a question, is it strong? Does the concrete set well with this method, or is there a risk of it not being structurally integrable?
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As I said everyone of you can point out flaws in the wall and I can tell you the exact reason and solution for each one. I'm willing to do a friendly wager with one or all of you. The butt ugly one comment was pretty funny but there is a solution to butt ugly also. I'll just explain it and if you aren't a believer after that we'll then I'll post the URL to the video then that will shut you up. 1 when laying the bags in starting with the very first layer. We use a gasoline powered asphalt tamper. Compacts and makes a uniform shape inside the bag. Prevents cracking and chipping. Very layer down and back. 2 every 3 layers we backfill with gravel after installing a perforated 4 inch drain pipe. Every 4th layer we install our rebar depending on height we use 3/8 or 1/2 steel. We install it vertically at an angle every other bag down then every other bag up creating an x pattern so the concrete is tied together on either side. 😁 Make sense? We also install dead man bags every 10 feet with steel running horizontally. Okay so we repeat this process until the desired height is reached. Watering as we go . Who says watering concrete doesn't have a benefit ? So anyways we are all backfilled,tamped, reinforced,and now the cool part. We usually wait a minimum of 20 days we check the wall by removing some.of the paper. See how light the concrete is and how hard the bag is by testing it with a core drill. Wow genuis right? 10 holes we can evaluate the wall or section that may need more time. It's called diligence. After the tests we decide whether to move forward. The butt ugly comment solution . We burn the paper off. And repair any little imperfections along the wall.we then pull out to backpack sprayers one five gallon and another five gallon we mix her base color in the first one then we mix the overlay and the second one. See where this is going. We sprayed the first base coat on while the first one still wet. We splatter the second one and let it run through the first base color for a marble effect when it dries we seal it guess what. Butt ugly fixed. Now you still want to doubt it I'll post a video. I catch you out use my patent I'll put you in the courthouse. Just kidding there is a correct way to do it even though I was being sarcastic.
Wait in have one last question for Austin since he's a resident expert on the bag walls. Have you ever seen one done with my patented process? I bet you haven't. My email is email@example.com email me I'll be happy to show anybody here that what he says is not factual in any since of the word. I can prove what I'm saying.
There is a correct way to do the bag wall. There's is also a certain company that manufacturers a bag that helps the curing process. And if a wall is chipping or crumbling it's fair to say the bag was taken off way to early. 1 I have been doing these walls for 30 years. 2 I have tested several types of bags. 3 that video above with the guy putting steel in the bags is my video. 4 I can disprove your theory that the concrete will not set up correct due to water ratios. 5 I'm not pouring a pad where curing to a certain strength is absolute. 6 after it's cured and prepped for small imperfections i stain it and cure just like it's a flat sidewalk. 7 regular 16 inch estate blocks at home improvement stores don't even have steel in them and move individually. My wall well it's all tied together with 3/8 or 1/2 reinforced steel you tell me. 8 if the water percentage for concrete has to be so precised why is their a variation in that percentage called a "SLUMP" . seems if it was absolutely imperitive on the water percentage based on the strength seems there would only be one "Slump variation. Don't judge something based on people's lack of knowledge on how you install a wall made from bags. 9 and I'm off soapbox. I do have an in depth instructional video on how to and the formula for calculating all the materials anyone would need. Anyways I'm not bashing anybodies opinion if it is fair and educted. I have walls that's been standing 30 years with the same process. Perfected and tweeked over the years and still improving it as it progresses.
Why not to do this:
1. Concrete will be very weak. (Look at second to last photo.)
2. This will be a seismic disaster.
3. It is butt-ugly.
4. It is very expensive to buy concrete by the bag. That's fine for small projects - I do it - but not for huge ones like this. You also might notice that they make these walls massive to counteract points 1 and 2. That raises the price a lot more. Of course stack blocks are not cheap, either, but did you do the total cost analysis? I bet a nice stack-block wall isn't that much more expensive, if any.
5. It makes my back hurt just to think about moving and positioning all those bags of concrete. Even those little 50 and 60 pound bags. (And they are a lot more expensive per pound/ton than the 90 pound bags.)
I buy bulk prices and I get the bags for $1.87 per bag theory debunked . Have the receipts.
I forgot number six:
6. That paper is plastic lined. Where does all that plastic go? Seems like a lot of it will be around your yard for years as it comes loose or works out of the cracks.
There is a commercial available product called Rip Rap made by a few concrete manufactures (the 4th image in the post features it). It's only used for erosion control.
Mike Haduck knows what he's talking about. https://www.youtube.com/watch?v=5fndKimsWnE
This is bad and lazy. It does not take much looking to find cement blocks for what it costs per bag of
quickrete. OR, Rent a damn mixer for $50 a day and mix and pour a wall. You would probably use less by doing so because; you could pour a rise and distribute gravel in the center. Then pour your next 6"... behind the wall needs a french drain preferably leading out to daylight and a layer of gravel and on top of that, straw or silt barrier. And about halfway up the wall, a piece of geogrid to be backfilled over.