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Are there any structural engineers on here?


BIGGUNDOCTOR

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I have a question about wall construction for a shop and nontraditional building techniques. 

At work we go through a mess of the "super sacks" they are 35" square and 52" tall when fully filled. We are averaging a couple dozen a day, so I could get a thousand in a short amount of time. I would like to build a shop space and got looking at these sacks. The ones we get are rated for 1,000kg and have a 5:1 safety factor. My thought is, fill them with the sand and gravel on my property and stack them. My general questions are ; rebar amounts, shotcrete thickness, how much side load does sand and gravel exert sideways in a berm or direct burial situation, is this a feasible idea? It gets pretty hot here for 3 months of the year (113F today) and I am thinking a 35"  minimum thickness wall would provide a good thermal mass to help block the heat, or for maximum barricading , go subterranean/berm the wall. I like to try and cut waste when possible, or find other uses for items headed to the landfill.  I'm not looking for a full report, as I know every area is different and local codes apply. Just some general guidelines that I can start with for researching this. 

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Interesting idea BGD, sort of a mud brick/ adobe method, the structural ability would be quite high given the large base area, but a couple of problems you might face are; while the filling is dry the bags will settle and "nest" together very well and become very stable, but full sealing of the joints, especially vertically will take a bit of thought. The other thing that comes to mind is are the bags uv resistant? Or can they be made uv and weather resistant? If not , depending on the material the sacks are made of, they will deteriorate pretty quickly and your dry mix will probably leak out, so you may need to add a binding agent and water to the mix, then that becomes a procedure issue, to either fill and cure the blocks in a uniform shape prior to installing, or filling and installing immediately and letting the bags nest and conform to each other as they cure. From there, the next issue would be how long to let the structure settle before shot creting, and you will need expert geo advice for that and if you have extreme weather/ temp changes, it could be a party stopper. This is by no means authoritative advice, just my thoughts from many years in construction, I hope you manage to sort it out as the idea itself is pretty sound, but you do need to get it right.

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I have seen construction where sand bags (smaller than yours) were filled with concrete and stacked which allowed them to droop and nest while the concrete was soft.  This locked them together.  after a few years the sand bags disintegrated from UV but the concrete remained solid.  I think the trick to constructing something like this would be to mix the concrete and fill the bags at the same rate as they would/could be placed in the construction.  Timing and synchronising of all the steps would be crucial.  Also, bags of the size you mention would be HEAVY when full of anything.  You would need machinery such as a back hoe or a good size fork lift to move them around.  It would not be hand work.

"By hammer and hand all arts do stand."

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Sounds like a better job for a hesco container or a Gaylord shipping container. Some chain link fencing may help stabilize the side load. Posts driven into the ground on the inside and outside of the wall might also work. I'm just brainstorming ideas though.  Years ago I built a structure from old tires filled with dirt and straw that sort of looked like a cartoon igloo. It stood for at least ten years that I know of but could be still there today for all I know. Good luck.

Pnut

 

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Should work. You'll need gravel that compacts hard and a little cement in the mix. You want concrete with almost zero slump.

High lift off road forklift to hold the bag open and in position while the concrete truck fills it. Repeat on the next in line and so on around the wall. Once set and cured repeat the procedure for the next layer.

Second layer and up will slump into the layer below and should make a darned tight seal, especially if you put a concrete vibrator to them. Place the bags a little closer together than they are wide and they'll slump into tight contact.

You could use compacted or cement stabilized & compacted soil but you'd have to fill and compact them in lifts. You might need something to hold the outsides of the sacks while you compact as well. I don't know if you could fill and compact the supers on the ground then lift them into position. If I had to bet on it I'd say not likely.

Gable ends would be cool, like step pyramids.

Frosty The Lucky.

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  • 4 weeks later...

For sand and gravel it is recommended to double bag (you still need to plaster the bags to protect them from UV. A meet trick is to have a foam roofing contractor spray and seal the bag wall. Tire Gambians work well as well, just cut out one side wall (a razor knife works well but a saws all with the blade sides ground down to remove the curf is faster) they can be packed with soil, sand or gravel. Us military flips shipping containers over (the floor is designed to carry a load) and sand bag (they do use special big bags too) around and on top. Tire Gambians keep the sides from collapsing) if you earth burm or beery. Many ways to skin this cat. 

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I wonder how I had missed these responses earlier....

 

Random thoughts.........

FIBC bags AKA; Super Sacks are made from woven polypropylene , and will last around 1 year in the weather, per manufacturer recommendations. They are not water tight.  The shotcrete, or possibly adobe like the natives here used, or some other coating,  would be put on to protect the bags from the harsh UV we have here.  We get more sun than anything, and only around 4" of rain a year. Snow is a very rare dusting.

I have an 8,000# Champ rough terrain forklift with a 25'-30' reach. A sack of gravel should weigh around 2,900#. if filled with one yard.

I have also looked into the shipping containers as walls - big LEGOS, and companies now build arched roofs to fit over spaced containers. It will get down to what I have more of in the way of time and money. I have 2ac of sand and gravel...  With the container walls I was looking to bury them so they don't become ovens in the summer. I have about a 25' drop in grade from the house to the side street, and to get to street level will take just 6'-8' of digging on the lower section as it was graded for a horse arena by the previous owner. My thoughts on stiffening the outer wall was to cut the inner wall out and weld it to the outer then filling the formed hollows with concrete to form pillars. I read that a container is designed to hold 192 metric tons (211 US tons) on top of it, well on the corner pillars, but the sides need bracing if buried. 40" containers are running around $3,000 from the dealers, a little less at auctions. I would like to use the 53' high cubes myself.

When I was moving here I looked into all kinds of alternative construction techniques. The rammed earth using the tires was particularly interesting as you can get the tires for free, but they are labor intensive. Also looked into straw bale.

I was doing some quick figuring and we go through around 5,200 sacks a year.

Concrete tilt ups are nice, but very expensive, concrete isn't $50 a yard anymore. My neighbor put up a 40'x60' metal building and the foundation alone was $27,000, with a total of $60,000.

Thanks for the input!

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One thing that you need to make sure of when using alternative building materials and/or techniques is that there aren't any local or state building codes of which you could run afoul.  Where I live it is unincorporated county with no building codes and I could do any darn fool thing I want to.  Be it on my head.  However, in other states and counties there may county building permits and codes.  In some states there may be state level requirements.  For example, in Colorado the building codes are adopted and enforced by counties but the electrical and plumbing codes are state level.  In rural Nevada I suspect that you are OK, as I am in Wyoming, but it is worth a phone call or two to make sure that you don't get yourself wrapped around the axle and waste a bunch of time and money.

"By hammer and hand all arts do stand."

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Thanks John.

shipping containers sub grade require Gambions (adaptive text defaults to the other spelling) are required to prevent bowing of the side walls due to creep. Tho I imagine one could shot creat the sides. I have considered stacking three containers so as to have a central bay spanned buy one container (seemed a better use of material than three side buy side) a light steel frame to support steel roofing would go pretty fast. The corner posts are strong (in  fact you only need foundation posts at the corners, tho you will probably need an engineer to get past an ignorant code official) but the roof is only rated to be self sorting with a snow load (the reason that the military flips them over to make Correa for sand bag bunkers. 

The Folks working with earth bags recommend dubble bagging for lose fill like sand and gravel, wile the points of the barbed wire prevent lateral movement. You might want to experiment a bit to see how much the bags deform so that you can place them without putting to much force on your containers. If you need stabilizers I would recommend fly ash, for a project using that volume of soil it’s much cheaper than cement (tho much weaker) and your nearest coal fired power plant will be happy to see it gone.fly ash is in fact used to extend cement and to stabilize foundation and road bed soils regularly. 

As to tires, cutting out one side wall (drop it inside) and use an air or hydronic tapper (designed for the tamping in power poles) greatly reduces labor. Not that sand and gravel will take much to reach 99% compaction. 

Earth bags, tires and shipping containers are fairly easy to get approved as they have been used before, have engineering specs available and actualy been codified in the latest UBC (not that ignorance, predudice and stubbornness can’t be a problem with code officials). 

 

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Even if the latest edition of the Uniform Residential Building Code provides for something that does not mean that the code adopted by the local jurisdiction provides for that.  A local jurisdiction has to adopt a specific edition of the code with local amendments.  These do not automatically update when the national code committee makes a change.  Some places are pretty good about updating their local codes when a new edition comes out (every 2 years IIRC) and others can go for years without changing anything.

"By hammer and hand all arts do stand." 

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They just decommissioned the local coal plant and they are almost done tearing it down. Fly ash was one of the main reasons they closed it. It was the cleanest, or second cleanest coal plant in the nation, and recently had millions spent on scrubbers and other equipment.  I asked a guy who worked there why didn't they convert to natural gas?  He chuckled and said politics, the gas pipeline was already run out there, and it would have been an easy swap. But Harry Reid got it shut down for good for brownie points.

Yes, local codes will have to be addressed , and unfortunately Clark County can be a big B to deal with on some items.

 

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If a person runs into a problem with building, etc. codes there is usually a variance process to get around the problem.  The standard for granting a variance is usually that the strict application of the code provision would cause "undue hardship" for the property owner.  Much higher costs, impossibility due to natural features, extreme difficulty in being able to find contractors or specific materials, etc. could be undue hardship.  Just, "I want to do this because it is slightly cheaper." isn't going to be undue enough.  Also, the issue of safety and how what you want to do may impact the neighbors are significant issues.

Some places are pretty reasonable about granting variances and in some it is a practical impossibility.  Sometimes the cost of getting a variance is more than the cost of complying with the code.

Finally, it is worth knowing at what point a particular code kicks in.  For example, something less than 100 square feet may not invoke the local building code and something that is not going to be used for residential purposes or retail or have employees may be outside the jurisdiction of the code.

"By hammer and hand all arts do stand."

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If I had to recommend what to stress when requesting a variance I would say safety and compatibility with the neighborhood.  For safety you would need to show that what you want to do is at least as durable as something conventional and code compliant.  There are also regional issues such as how things will interact with a high water table e.g. will a steel shipping container rust out over time?, wind load resistance (an issue in tornado or hurricane areas), or snow load (important in northern or mountain states).  Also, does what you want go along with how the neighborhood looks at present.  If you are rural there may not be many neighbors to compare with but if you are in a more settled area the county or whoever will want to see more compatibility.  Even a large metal shop building may look out of place in a neighborhood or Arts and Crafts bungalows.

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