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Cheaper, easier rammed earth technique.  RSS feed

 
Amedean Messan
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I was browsing the internet and spotted this image of workers toiling on this hand carried device. I had ponderings in the past of a device similar to this but I had not seen evidence of such a device until today. It is only an image, but the principle is basic and the simplicity of the design is incredibly easy to reverse engineer. I can see myself working on something like this in the future.

http://www.ruralhousingnetwork.in/technical/rammed-earth/Construction


 
R Scott
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It is called slipforming. It is an old technique that lost favor as mechanic tampers and skidloaders took over for weighted sticks and buckets. There are references on the internet of using it in the past many places.
 
Amedean Messan
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R Scott wrote:It is called slipforming.


Thank you very much for clarifying that to me, I will look this up.
 
Dale Hodgins
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This guy has a DVD for sale concerning slip form stone work. The long preview gives a pretty good idea of how it's done. --- http://www.youtube.com/watch?v=IIuVcvXzlZA

The Nearings were a couple who built their stone house with slip forms. Any search of their name will turn up something.
 
Kelly Smith
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there is a couple in my area with a rammed earth home, built using slipforms.

the home is earth bermed and passive solar. they have a ~2k PV array and are net zero with the utilities. pretty cool place.

the walls are ~18 in thick and the guy said he was using a "whacker" to compact the dirt once in the form.
he used a skidsteer to get the material into the form, and had a few high school laborers to help him.

i would love to replicate this design, as i think its a good mix between eco building and mechanized building.
 
Dale Hodgins
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I love the simplicity of this slip form. He foot stomps only. If more braces were used, a similar form could be rammed with a tamper. Steel pipe could be used as well. Cob could be formed like this.

This is in the Indian Himalayas. The man doing the work looks Tibetan. The film people are speaking slowly to him, so I assume that they are from further South and they speak different languages. ---

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I've asked one of our members for a translation of anything regarding this process. It's late at night on the west coast, so I don't expect she will see this tonight.
 
R Scott
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Dale Hodgins wrote:I love the simplicity of this slip form. He foot stomps only. If more braces were used, a similar form could be rammed with a tamper. Steel pipe could be used as well. Cob could be formed like this.

This is in the Indian Himalayas. The man doing the work looks Tibetan. The film people are speaking slowly to him, so I assume that they are from further South and they speak different languages. ---

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I've asked one of our members for a translation of anything regarding this process. It's late at night on the west coast, so I don't expect she will see this tonight.


This video was an inspiration to do rammed earth this way, but with a jumping jack tamper (can be had cheap used). But my foundation needs meant I would have had more concrete in the foundation and stem wall than doing the whole thing in block.
 
Rebecca Norman
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Hi Dale,
I couldn't download the whole video yet, but the title says it's in Spiti, where the language is just different enough from Ladakhi that I probably won't be able to follow it. It's like Spanish and French.

We've been doing lots of low-tech rammed earth here in Ladakh, though, where the ancient rammed earth technique is similar to Spiti. I think in Spiti it has been used for houses all along, and I know it has in Bhutan. But here in Ladakh though the ancient castles are made of it, modern houses use only adobe bricks, and this rammed earth was only used for rough fencing.

So we resurrected local rammed earth 20 years ago, and have built about 10 solar heated buildings using it, some of them large.

Our forms are as long as walls or planks. The head builder sets up the forms and gets it plumb. You can move the frames after a day in hot weather or two in autumn, and then build on top of it after several more days. We use a cement mixer for the mud. We stamp by hand with a wooden or metal stamper. Laurie Baker's classic book My Name is Mud has wonderful simple hand tests to find the right mix of your local materials -- he was talking about all kinds of earthen building.

I'm enjoying the coziness of our first big solar rammed earth building right now as I write -- it's below freezing outside and we have no backup heating, only solar.

My internet access is slow today and I've had trouble opening Permies pages or clicking reply, so I won't try to upload photos right now. We've got a few on our website, www.secmol.org, but I've recently scanned our old slides from the 90s when we were building this building.

More recently, Sonam Wangchuk, the brains and energy behind our whole thing, has been instead initiating modern style rammed earth with two local companies that do solar heated earth buildings, his protoges. He learned it at Craterre in France, David Easton in California, and in Australia. It uses big smooth forms a whole storey high, pneumatic ramming, and often some percentage of cement. Maybe it's stronger or more earthquake safe, but I really love our old cob-like hand rammed earth buildings. These walls are cozy. The modern system is more mechanised and maybe that's a big advantage as wages in this country are rising fast. I'm not sure if the jury has decided on that, though, since the modern system is more picky -- you aren't going to plaster so you have to get everything perfect inside the form.

 
Rebecca Norman
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This was a solar heated building we built for a client. Hand stamped with a tamper.
Building-Construction-5-copy.JPG
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Low tech rammed earth in Ladakh approx 2000
 
Rebecca Norman
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Sometimes it got a little funky.
Building-Construction-29-cropped.JPG
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Rebecca Norman
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On the north wall of our office, which can't be bermed, we made a thin cavity wall and stuffed it with clean(ish) garbage. Since it doesn't have any passages or connections with the interior space (ie that smoke could move through) we used plastic. The cavity wall is only 6 inches thick while the main wall to the right is 18 inches. The sticks go through to help support the skinny wall. The stones are often jammed in one course of rammed earth to bond it to the next.

The exterior got soaked in a flood in 2010 so we stripped off the cavity wall and insulation, and actually the building is still warm enough so we didn't put it back.
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Cavity wall to be filled with clean garbage for insulation
 
Rebecca Norman
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The frames were really simple, planks tied with pipes with holes in them, and stoppers made of rebar to keep the spacing regular. After the layer dries for a day or two and is hard enough, pop the stoppers out, tap the pipes out, and move the frame to a new spot. After a few more days, the next course can be added on top of this spot.
rammed-earth-frame.JPG
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Dale Hodgins
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Thank You Rebecca. Your explanations and photos go way beyond the translation request. It's great that you're reviving this building method. Do you have a thread that tells all about the history of what you've been doing in India for 20+ years ?
 
Rebecca Norman
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Location: Ladakh, Indian Himalayas at 10,500 feet, zone 5
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I'M SORRY I HIJACKED THIS THREAD!! I'LL STOP NOW.

Because it is going to be plastered, and can be chipped and shaped, and it's easy to make odd shaped forms such as arches, this style of building has some of the charm of cob.

And because it's not as densely rammed as modern rammed earth, I find it warmer. It's not as dense because the mix is wetter, so there is water in the pores so it can't be as compacted as a drier mix, and because the modern rammed earth uses mechanical ramming. The water dries out from the pores leaving pores, yay! (Warm)

I try to understand the insulation debate, but all I can say, is from decades living in Northeast US in balloon frame houses with insulation and central heating at 68F, I prefer living in these houses here with 18 to 24 inch earth walls that provide both thermal mass and some sort of insulation, even though they're down around 60 from mid-Dec to mid-Feb. I'm not sure R value is really relevant to such structures.
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Dale Hodgins
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It's not highjacking when you have first hand knowledge that relates to the topic at hand. I'd be happy to view 100 photos of the school and other buildings. Thanks again.

Do they do anything to deal with the risk of earthquake ? Are today's buildings substantially different from what was built historically ?
 
Rebecca Norman
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Ah, earthquakes. There have been no notable earthquakes in Ladakh in recorded history, but it certainly is a risk, and this mountain chain is rising of course. So in our earlier buildings we always had a strong wooden tie beam embedded under the floor or roof beams at each level, so that in the event of a section of wall coming down or cracking, the beams wouldn't fall on your head. My brother in law, a green architect in California, said he thought our walls were thick enough that in most earthquakes the center of gravity or whatever it's called wouldn't move out of the space occupied by the wall, so it should be good except in a really Big One.

Still, some sections of our school building had too much glass, ie the entire south wall of some rooms was 2x4 frame with glass, wrapped around about 6 feet on the east and west. These were not earthquake safe, and were also thermally too extreme -- too hot on a sunny autumn or spring day, and too cold on a winter night or morning, so finally we rebuilt the south end of the central bay of our big hall last year using the modern pneumatically rammed denser stuff, with a load bearing south wall behind glass, wrapped solidly around the corners.

In the new system, Wangchuk uses concrete tie beams not only between each story but at the level of door and window lintels, for more earthquake safety. He also ties sections together by embedding a piece of that superstrong green plastic mesh in adjacent sections. Since we first built this school, there was a destructive earthquake a few hundred miles away in Kashmir. It was barely felt here, didn't make windows rattle, but it did shake us into more awareness. Also, in those years, he went and did a masters in Grenoble at Craterre, where the more technical and risk preventive western ways of thinking prevailed.

Some of the differences with historical buildings we look at... Well, they are often 4 feet thick at the base and fairly steeply tapered, and go up several stories. We haven't gone above two plus a skylight/clerestory with ours, and we don't taper except sometimes doing 24 inches for the ground floor and 18 inches for the upstairs, with the difference on the interior. They had very shallow courses, maybe because of the limited forest in Ladakh, whereas we can get nice big planks from Kashmir. A very encouraging thing about the historical buildings, for example the ruins of forts on hilltops, is that the rammed earth walls are standing untended for centuries, surrounded by rubble of stone structures. They often have had the wooden lintels torn out (wood is REALLY scarce here) but this leaves either a fabulous flat earthen surface hanging there above an empty doorway, or a bit crumbles out and then it stabilizes in a rough arch shape and just stays. A few have large cracks like an inch wide or more, perhaps from settling foundations, but the cracks are eroded enough to make you think they've been cracked and standing happily for centuries. Some of these abandoned hilltop forts have not been used or maintained in historical memory, several hundred years.

Of course a huge difference between even our earlier buildings and the traditional ones is glass! The implications of that are huge.
 
Abe Connally
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We did slipform adobe in a similar way. Small, interlocking forms worked best. We tried a variety of different forms. One was the T brick form:


When you line these forms up on the wall, the space that is created where the forms meet creates a gap in the mud. So, for the next level, you shift the forms 1/2 a brick over, and the gap is right in the middle of the brick above it, forming a T. We put the adobe in the form, waited about 10 minutes, and then gently pulled the form straight up. You can then set up the next few forms, and pour again. We were able to do 2 levels of brick in a day in our dry climate.



Here's a bit of information about T bricks

We expanded this concept to make the bricks taller and just filled the gap by hand:




The brick forms here had bolts and nuts, so came apart from the sides. Again, wait about 10-15 minutes, then take the forms off and move along the wall.

We put bottles and special niche forms in the mud to give the wall a bit of character:


Here's some more information on how we build with adobe
 
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