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+--- Thread: Lava-Cement to replace Ferro-Cement? (/showthread.php?tid=8328)
Lava-Cement to replace Ferro-Cement? - OpenD - 02-24-2011
I'm a big fan of Monolithic ferro-cement domes. They're earthquake proof, can withstand a direct hit from a Force 5 storm without structural damage, are very economical of materials as well as inherently energy efficient. And they use sprayed-on or troweled-on concrete, kind of like an inside-out swimming pool.
Now they've adapted their Ecoshell design to replace the iron rebar with basalt roving. Basalt... you know, we call it lava.
It handles like fiberglass but is stronger, won't rust, Pele should be pleased... http://www.monolithic.com/stories/monolithic-ecoshell-built-with-basalt-roving
RE: Lava-Cement to replace Ferro-Cement? - mikewj - 02-24-2011
The video to my mind is somewhat disingenuous when it speaks about the 'base cost' of basalt used to make the roving. Obviously there is a considerable cost in energy to convert solid rock into flexible roving, and this cost seems to have been conveniently overlooked. Also, when hurricane resistance is discussed, there was no mention of the cost of foundations and anchoring to keep the structure in place. Without a solid foundation, the structure may not shatter, but it certainly could move quite a long way! Almost like a one -piece small tent improperly staked, which blows away like a balloon in a high wind.
On the whole a good idea, but full disclosure as to actual cost would be nice.
RE: Lava-Cement to replace Ferro-Cement? - OpenD - 02-24-2011
Yeah, I thought the material cost mentioned was a bit goofy... but I also know David B. South is a straight shooter, and he's genuinely interested in providing low cost housing in third world countries like Haiti. I think that Hawai'i is as much in need of this kinda housing solution as Haiti.
Anyway, I'm familiar with the Ecoshell process. Basically it's a rebar reinforced ring beam foundation, with a poured slab floor, then the dome is built on top, with the shell tied to the base with rebar stubs. It's incredibly strong. FEMA is using the method to build above-ground tornado shelters in the midWest.
The one residual objection I've heard to the Monolithic approach for use in Hawai'i is the use of iron rebar, which potentially could degrade under long exposure to wet weather. Replacing the iron with basalt fiber answers that issue.
Funniest moment in the video to me is David saying "I'm so excited about this," with no visible sign that he is excited, but then again, he's an engineer. :d
RE: Lava-Cement to replace Ferro-Cement? - Seeb - 02-24-2011
I would take anything Dave South says with a grain of salt ( or a truckload ). I’ve been to Italy Texas after one of their crappy mud pumps fractured my skull. Thin shell domes are a good idea, but all the monolithic people want to do is sell those plastic bag forms.
RE: Lava-Cement to replace Ferro-Cement? - Peter Epperson - 02-24-2011
When I was researching ferrocement techniques before I started my tank business I had planned on using an inflatable dome balloon to simplify construction. I figured you could simply inflate a balloon and spray it with a steel fiber reinforced gunite. Actually it works fine, even spraying on the outside of the balloon which is not how it's usually done. The trouble was the massive concrete footing required to support the balloon before during construction. I was able to convince, by phone, a balloon manufacturer and a pump manufacturer and the fiber reinforcement manufacturer to all get their respective products combined at one of their plants to test the feasibility of the idea. It worked fine on the 6' diameter balloon but like I said the footing required nuked the idea in the end. We went to our current design and discovered that it's not that hard to make domes with a steel armature instead of the inflatable balloon. It also allows way more design options.
RE: Lava-Cement to replace Ferro-Cement? - OpenD - 02-24-2011
quote:
Originally posted by Peter Epperson
We went to our current design and discovered that it's not that hard to make domes with a steel armature instead of the inflatable balloon. It also allows way more design options.
What is the size range you're talking about? For water tanks I'm guessing maybe 12' - 20'? I could see an armature arrangement working there.
For larger buildings, a 150' church building, say, I think the airform is a great technique. I've been in a number of churches, schools, and private dwellings made the Monolithic way and found them brilliant.
RE: Lava-Cement to replace Ferro-Cement? - OpenD - 02-24-2011
quote:
Originally posted by Seeb
I would take anything Dave South says with a grain of salt ( or a truckload ). I’ve been to Italy Texas after one of their crappy mud pumps fractured my skull. Thin shell domes are a good idea, but all the monolithic people want to do is sell those plastic bag forms.
Sorry you had a bad experience. Monolithic is in the business of selling airforms, yes, so I'm not clear what your complaint is. There are maybe 100 residences in Texas already built using the Monolithic system, and they typically require 50% the energy of conventional construction. There are also a number of large school and church buildings built that way .
I've always found the Monolithic people to be great to deal with.
RE: Lava-Cement to replace Ferro-Cement? - dmbwest - 02-25-2011
A good write up on Glass vs. Basalt.
http://www.compositesworld.com/articles/basalt-fibers-alternative-to-glass
Tried and re-tried it a couple times over the past 12 years. Don't like it as much as glass or carbon. Side note to this, as badly as I wanted the bamboo cloth to work, it failed miserably as well.
aloha,
pog
RE: Lava-Cement to replace Ferro-Cement? - Jay Bondesen - 02-26-2011
I partnered in a polyurethane foam company, Foambuilders Corp., in Colorado in the late 70's. The South family at that time was starting out doing potato storage buildings in Idaho using inflatable airforms along with foam and gunite for large span structures. We had actualy moved to Boulder after working with foam in California for several years so we could work with a couple of architects that designed dome structures. It was a fun five years but we just couldn't support the business doing a few custom dome houses. The early domes of 35' diameter or less were self-supporting at about 4"-5" of foam with 1/2" of plaster or another cementacious interior coating. You end up with a strong insulated building that first shows up at the jobsite in drums and bags.
When the diameter gets bigger the polyurethane needs to be too thick to be cost-effective so the foam then becomes a form to apply the gunite onto and you end up with an insulated thin shell dome. The engineering for structural concrete is pretty clear so these newer concrete domes are easier to get through the building department. The insulated dome, with all of the work going on inside an inflatable, was a good fit for building in the midwest.
Anyway, I'm a fan too.
Jay
RE: Lava-Cement to replace Ferro-Cement? - dobanion - 02-27-2011
All the rebar and the difficulty of wrapping/bending/wiring it was what turned me off of monolithic domes previously.
This is fantastic.
And, you can use the same airform over and over, when built "Ecoshell" style like above.