Yurt Platform

I am learning all about yurt platforms. They are always exactly the size of the yurt – that's critical. When you see decks around a yurt, they are a separate deck from the circle that is the yurt platform. That circle generally is raised above the deck a bit to keep rain/snow out. Yurt platforms can be made from SIPs panels, composite material, lumber, or concrete. Now, if you can make them from concrete, then you should be able to make them from concrete alternatives, right? Right!

(A wooden deck or SIPS panel deck would be easier, but a lot more expensive.  So, we're going with sweat equity here!)

We are looking at making a concrete alternative floor/platform for our yurt. Brent is currently experimenting with the soil from the property (seems to have a decent amount of clay for concrete alternative floors). It is something we had already been thinking about for our house, so why not try it out with the yurt first?

Some options are soil concrete, stabilized adobe, poured adobe and tamped/rammed earthen floor (may or may not have a stabilizer added). He is currently trying out different “recipes” for these flooring options.

Fortress Yurts is very supportive of our thinking in this direction. They want us to let them know if we go this route as they will change the bracket type they use for attaching the lattice to the platform so it will be easier for us and they will shorten the walls a bit to fit the type of platform we'll be making. So nice to have such eager support.

Brent did a couple of very basic soil tests to find out the percent of sand, clay and silt in our soil. The first one, he didn't really dig down deep enough. The second one, he dug down into the yurt site 6-12 inches. He put this dirt in a half gallon mason jar and did the “jar test”. So, the jar was about half full of soil, then you add a tablespoon or two of dish detergent and then water until the half gallon jar is about three quarters full. Then you shake for 5 minutes. Let the jar sit for one day. Then you measure the height of the settled soil in the jar. Then shake for 5 minutes. Next, measure the height of the soil that settles in 30 seconds. This is your amount of sand. Then, after 30 minutes you measure the height of settled soil and that minus the height of sand is your amount of silt. The difference between that number and your total amount is the amount of clay.

Our results: Clay Loam. This is considered a good type for making adobe. (Yay!)

So, Brent's recipes:

1. Full on Adobe: Soil mixed with water to a wet cement sort of consistency.
2. Stabilized Adobe tamped earth style: 2.5% Portand cement, 2.5% hydrated lime and 95% soil. Lightly dampened while tamping.
3. Stabilized Adobe Brick: 5% Portland cement, 5 % hydrated lime and 90% soil. Mixed like concrete.
4. Soil Cement: Same as a cement mix, but use soil instead of aggregate. Brent also added the hydrated lime and cut the Portland cement in half (so 12.5% of each of these).
    

(In the picture, it is #1 to #4 left to right.  #3 and #4 have been linseed oiled in this picture.)

All mixtures were put into a “form” which happened to be a plastic drawer. #3 and #4 cured in two days, though they were removed from the forms after about 6 hours. #1 and #2 were set on their sides out of the forms after two days and cured for another 5 and 3 days respectively. Once cured he has added three coats of boiled linseed oil (couldn't find raw in town) to the top of each “brick”. So, as of today, each brick has had a total of 3 coats of boiled linseed oil. The oil is to seal the material so that you can sweep and mop your floor and it is protected from stains.

#4 was puddling and sticky, so it really wasn't absorbing the boiled linseed oil from that 3^rd coat well. Brent notes that as the cement decreases the amount of linseed oil absorbed goes up. In another week, he will do the dreaded “drop test” where each brick will be dropped from chest height onto a corner on the ground. The result (cracking, breaking, shattering, etc) will offer insight into which recipe to use. We will go with the lowest cement content that offers acceptable results.

Our ideas for the details are evolving as we dig.