I agree that they’re certainly much more expensive than a Hexayurt. The question is whether they can last and be comfortable for 5 years or more, over the course of a long reconstruction process -and with these medieval structures restoration could be really protracted -especially if the government can’t stay focused. In the early 70s German engineers provided earthquake victims in a mountain region of Turkey with a unique emergency housing solution; polyurethane foam domes made by mixing the chemicals in a membrane form and letting it foam up into the dome shape. They could then peel away the form for reuse, cut the openings they wanted for doors and windows, and a few people could carry the whole thing to the final location. It was designed so they could bring all the materials and tools in on mules or by air. For emergency housing, it was pretty good, even though the polyurethane formulas of the time were hazardous and highly flammable. But it was only intended to be used for about a year. Thanks to regional poverty -leaving people with no option to go anywhere else- and a grossly negligent government, some people ended up living in these for 10 years or more -though most of them burned down or disintegrated by then into a powder that was blamed for some chronic respiratory ailments. A few were still standing, though, some 20 years later. Instead of waiting on the government, occupants scrounged for materials and built permanent homes around them.

I hadn’t heard about this shotcrete variant of the Hexayurt before. This sounds like it has some much longer duration use potential. Reminds me of Dante Bini’s Minishell system -something long before the Hexayurt and far more labor intensive that I recommended to Columbians when there was a series of massive floods there some years ago. They were specifically looking for something based on concrete that they could use for fast-build low-cost permanent housing in these rural areas where equipment was hard to bring in due to the lack of or destroyed infrastructure. There really was no pre-existing architecture left to restore as whole communities had to be moved out of the flood zones. So they wanted quick permanent dwellings that would let them remake whole villages. The Binisystem (http://www.binisystems.com/) was originally intended for large scale concrete dome construction. You would build a slab foundation then lay down this deflated pneumatic form. A rebar mesh would then be constructed on top of that and a slab of slow curing concrete would be poured. At just the right point in the curing, the form would be inflated to make a huge dome shape -we’re talking 40 meters in some cases- and then it would harden into the finished permanent dome. The Minishell system was a miniature version of this. It worked the same way but was designed to make square-base domes with two or four arched open sides that could be linked up into larger complexes. Not unlike the Monolithic Dome concept, but supposedly faster and with the form balloons reusable. What was good with this was that you could easily use conventional by-hand ferrocement later to expand or modify structures, though it had the downside of being a bit too permanent. This is a tough material to expand or modify. I never did find out the results of that project in Columbia. A more modern version of this emerged a couple of years ago in the form of a concrete-impregnated canvas. (http://www.concretecanvas.co.uk/index.html) You inflate a structure then hose it down with water and it cures into a fiber-reinforced concrete shell, though it has the down-side of being combined with an inner lining of architectural vinyl which people shouldn’t really be living in. Was intended particularly for field hospitals where the interior remained sealed and sterile throughout the construction. I can’t recall if this ever got to mass production. Seemed to have some great possibilities, such as instant ponds and pools and tension-formed structures where you just tension the fabric into a hypoid or conic form with some cables like a tent, then harden it into a rigid shell. Maybe just a simpler variant of the Minishell; just put down a spherical balloon, cover with the concrete cloth anchored to four points, inflate, hose it down, instant free-standing pavilion.

Bini had some clever self-erecting structural systems you might also find interesting. He’s had a particular obsession with the concept of pneumatic lifting systems which started with the Binistar System, a method of erecting large span space frame structures using automatically locking joints. So the frames would be assembled flat and then this big balloon would lift it into shape and they would automatically lock in place. This has actually been implemented. It was used in Italy for erecting World Cup facilities in 1990 and in Spain in 1991. He came up with a relief housing concept based on this same concept called BiniShelter. It was a simple pre-fabbed conventional stick frame or SIP panel cottage where the panels were shipped folded and then, on delivery, you would activate this little pump to inflate a balloon that would lift the structure into shape and then special joints would lock everything together. A bit elaborate, but clever. He also had this clever relief tent concept called the Autotent -a tetrahedron shaped tent whose struts had spring joints so you could drop these out of a plane and they would pop open as they fluttered down, ready to use. They were a bit small, but could be combined into octet complexes to make a larger dwellings. Of course, similar tents exist now based on tensioned carbon fiber struts.

Getting back to the shotcrete, have you explored the use of Tridipanel (http://www.tridipanel.com/) and its related products for this? Was wondering about how it compared in cost and labor. Tridipanel (known also by a host of other names) is a pre-made wire rebar panel with integral foam insulation. Very efficient for making insulated foundation slabs but has a great variety of other uses. You build things by cutting the panels into a desired shape just like SIPs, then you tie them together with wire, pre-install utilities conduits and plumbing if you need them, and apply shotcrete to both sides. Gets a lot of use in commercial building and lesser use for low cost housing projects. Because it’s flexible enough to bend into gently curved forms, some architects like to use it to explore more organic shapes without going to the more intricate use of open mesh free-form ferrocement, which tends to be tricky to add insulation to. It should easily accommodate the Hexayurt panel shapes -though would be a lot thicker. But you could integrate a floor/foundation slab into the structure and make that at the same time as everything else. It would also be tough enough to make an upper floor deck as a loft or could support a hammock loft -a big six-point tensioned hammock. Whether it offers any practical advantages in the intended Hexayurt context is an open question, but it would be an interesting experiment. So many things I which I could try out myself…

Eric Hunting
[email protected]

Containers are incredibly expensive.

A hexayurt is, what, $130 in plywood if you do it Marcin-style. Add shotcrete and you have 15 square meters / 166 square feet for less than a dollar a square foot. If you want more flexibility or more insulation, costs go up, but the basic case is very very cheap. Think of it as a modular room.

Folding version means you can move it with the affected population, or when you change your mind.

What’s the problem you’re hoping to solve?

Vinay

—
Vinay Gupta
Free Science and Engineering in the Global Public Interest

http://guptaoption.com/map – social project connection map

http://hexayurt.com – free/open next generation human sheltering
http://hexayurt.com/plan – the whole systems, big picture vision