NOMADOMO
Nomadomo blog January 2020
I want to make liftable buildings. December 2019 this website went online. This section of the website deals with time-ordered matters, such as changes to this website, and new thoughts and events. Have fun! [Bert Frederiks]
2020-01-22 Self-supporting and/or flexible?
After an initial conversation with a structural engineer, I have a lot to consider. My idea that our structure should be "self-supporting" is unusual - with a reason.
Most things people make are "self-supporting" in the sense that they don't need to be supported to keep their shape. One of the few things I can think of that aren't is a loaf of bread or cake that hasn't been in the oven yet. They are limp or fragile. But houses and buildings are usually fragile too - a kind of dried dough that has to lie on a concrete floor or stand on poles.
If you build on piles, then I can understand this, because why not use the free strength of the earth for your house? But if you build on the ground then I understand it less. Isn't it better to put the strength of a foam-concrete slab, or something like that, in the house itself? I think that would be much better with strong winds, earthquakes and hailstorms. (Of course, there are other reasons to foundation than whether or not your house is self-supporting. For example, if you build a multi-story house and that is not a pyramid. And of course also if your house has to stand for hundreds of years and cannot be taken apart. Or if the ground is really very weak).
The forces on the beams of a self-supporting house are quite significant. If you don't make a foundation, you might look at it like this: if the house sinks at one corner, the opposite corner will hang in the air - an ordinary, fragile house would tear and break. With a real self-supporting house it will be a little less bad, because in this situation you would push away some ground in the middle. Also you would deliberately not build a foundation in the middle. Furthermore, unlike an ordinary house, our house is lightweight. But laying a layer of earth on the roof to grow vegetables is really a challenge.
Sufficiently strong beams are easy to find - but perhaps not really liftable. What is especially challenging is the coupling of the beams, especially at the ends. In my idea of the partly foldable floor, for example, some beams are mounted together at their ends. This can't be done just like that, because then the beam splits too easily.
Instead of making our house like a rock, we can also let it be water. The wall parts don't have to be mounted stiff together. We can allow them to sink, but there may not be openings. We accomplish that if from ground to roof a wall section is a stand-alone tower. Suppose this tower is 600mm wide. Couple them together with two or more connecting rods (or cables or ties) of 560mm length. This connecting rod is fastened on each side with one bolt and can therefore rotate around these bolts. If the wall sections then sag 45mm in relation to each other, they will be about 1.8mm closer together over the entire height - 560x(1-cos(arcsin(560/45)). This can be compensated with flexible filling such as compressed rockwool or rubber. In addition, this filling can "push back" so that less pressure is put on the ground below the subsiding wall section and a balance situation is created.
We can put each wall tower on adjustable feet. That's an old idea of mine, but contrary to what I thought at first, they cannot be at the corners of multiple wall sections, because then they can't sag independently. A levelling foot can stand on (or be formed by) an old car tire filled with foam glass granules (unfortunately not plastic-free). If a wall section sags too much, it can be adjusted, possibly with the help of a jack.
The floor has to be more or less one whole, otherwise you would trip over sagged parts. This is not such a problem, because the floor only carries itself and what is standing or walking on it. The floor can share its foundation (filled car tires) with wall parts. Where they sag, the floor hangs in the air. If the floor is flexible enough, you can also let it sink with it. Then you get a wavy floor.
It is better not to lay roof parts loose on rafters, because then they will not contribute to the strength of the roof. Think of the roof as consisting of strips that run from a wall tower on one side of the room to a wall tower on the other side of the room. Such a strip has two rafters on which boxes that form the roof are placed. Fasten them well on the rafters so that the boxes can absorb pressure forces at the top. The rafters take care of the tensile forces. The sealing between the strips must be flexible.
By the way - a completely different subject - now that I have read some more from Mike Oehler (see also) I guess that an earthen floor is also quite nice. His ideal was an earth floor with polyethylene and carpet on top - after all, our feet are made to walk on earth. In the Netherlands a piece of plastic always has to be somewhere under the earth because the house has to be gas-tight at the bottom - among other things because of possible radioactive radon gas. Thermal insulation (and gauze against vermin) only needs to be buried on the sides, under the walls. Make sure that the sun can come on the floor in the cold seasons and you have a heat buffer.
2020-01-15 3D-image of a floor
After a long time of trial and error I decided to create separate pages for 3D drawings. Browsers sometimes seem to crash on these and then people would not be able to read anything. I also think it would be nice to make a page with only references to drawings, with links to the text from there. It will looks somewhat like a photobook.
As a first example a part of a possible floor construction
. The more red coloured beams are link beams. If you remove them, the rest is foldable when the boxes are the same size - which is not so here.
Loading the drawing may take a while. The files are small, but your computer needs calculation time. If you click on the top-left image, you just get a big jpeg. This is for when the 3D drawing doesn't work on your computer. Clicking on the flags will take you to a corresponding text, like the one you are reading now.
2020-01-06 Concrete polution
"The cement sector is the third largest industrial source of pollution, emitting more than 500,000 tons per year of sulfur dioxide, nitrogen oxide, and carbon monoxide."(EPA) "Concrete is the second most consumed substance on Earth after water. On average, each year, three tons of concrete are consumed by every person on the planet."(2012) Concrete uses almost a 10th of the world's industrial water. "Wash-out water with high pH is the number one environmental issue for the ready mix concrete industry."(Morris)
Jonathan Watts wrote an article in 2019 for The Guardian and he says "the problem is bigger than plastic." "The dust from wind-blown stocks and mixers contributes as much as 10% of the coarse particulate matter that chokes Delhi". Yet, according to Phil Purnell, a professor of materials and structures at Leeds University, "the raw materials are virtually limitless and [b]y almost any measure it's the least energy-hungry of all materials." I guess this has to do with the durability of concrete. "Steel, asphalt and plasterboard are more energy intensive than concrete", Jonathan Watts writes.
To minimize environmental impact, therefore, we should try to reduce the quantity of concrete used in buildings, and use alternative types of concrete (with fly ash, for example). Woodfibers bonded in concrete is a good option. Only a few millimetres thick it gives a strong and fireproof material. Unfortunately it is expensive and it needs finnishing.
2020-01-02 Plastic, trees, micro-plastic, foodchain
Yesterday I read on the NOS news site: "Spain is planting forests again, and the polluters are paying." The trees are planted in square green polypropylene tubes. Thus, in a few decades, a forest of 450,000 pieces of plastic will disintegrate into trillions of trillions of plastic molecules that will stay with us for thousands of years.
Plastic cannot biodegrade; it breaks down into smaller and smaller pieces. Polypropylene is quite OK: "Leaching of additives and residual monomers from plastic pellets has been shown in a laboratory experiment where virgin plastic pellets made of polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC) and high-density polyethylene (HDPE) were kept in artificial seawater for 24 hours. Leachable components were found in all of the plastics except polypropylene."(Blastic) But what happens after 100 years? Also polypropylene attracts POPs (persistent organic pollutants), so it becomes dirty anyway. Maybe someday we can use it to clean the oceans from POPs?!
I didn't expect HDPE to leak. "HDPE resins are expected to be inert in the environment. They float on water and are not biodegradable. They are not expected to bioconcentrate (accumulate in the food chain) due to their high molecular weight." (The Dow Chemical Company) That's nonsense, of course: Eventually, after thousands of years, the HDPE molecules will get smaller. If not, they will be here forever - so are stones, but HDPE gets dusty.
Most plastic particles comes into the environment from car tires and clothing. 24% is dust from cities. "City Dust includes losses from the abrasion of objects (synthetic soles of footwear, synthetic cooking utensils), the abrasion of infrastructure (household dust, city dust, artificial turfs, harbours and marina, building coatings) as well as from the blasting of abrasives and intentional pouring (detergents)."(pdf) This is the category we do not want to be in.
What can we do to the earth without losing it? Not polluting at all is impossible. The earth is my home and the home of my great-great-grandchildren. Every decision has consequences somewhere and will in my head have to go in a scale. A layer of polyethylene or polypropylene half a millimetre thick enables the use of all kinds of (locally available) green materials, and the building remains edible. Sheltered from the sun this may be quite acceptable. But MUF binder (melamine-urea-formaldehyde) in so-called ecological OSB-boards? Read this summary of an EPA (Environmental performance assessment). I don't want it.