Rethink Your Life! Finance, health, lifestyle, environment, philosophy |
The Work of Art and The Art of Work Kiko Denzer on Art |
|
|
[Cob] WebsoilsurveyMom mon.pro at gmail.comSat May 9 16:41:31 CDT 2009
I am so glad someone brought this site up. This is a fantastic website, not only when trying to figure out what is the probable clay content of your soil (for cobbing) but is an essential resource when looking at property (to buy or rent), for building sites and growing food. There is all kinds if info for builders (drainage, foundation depth below frost line, watertable depth, hardpans, for supporting your building structure,etc). They can fairly accurately name the soil ok your site, but the thing to remember is that it is accuracy depends on how many holes they dug, so yes, things can change a few feet away. But anyone building anything, especially a cob structure, should really "dig" this site (sorry, couldn't resist). I agree that it isn't very user friendly, patience is key. There is a tutorial, I was just too lazy/impatient to invest the time. The more time you spend on it, the better you get at using it, and the more valuable it becomes, it is a veritable supermarket of information (it also tells you where stone outcroppings are, and if your soil has rocks), it is an addictive site. Also want to weigh in on the clay thing, all clays aren't created equal. The white clay mentioned is probably a kaolin (very old weathered clay, not much plasticity to it, low shrink swell ratio and not good for cob). The technical definition of clay particle is that it is smaller than .002 mm across, and some clay particles are flat (there are names for clay types too). Flat particled clays have great plasticity (are very slippery and probably generally better for cob in the right ratio) and will have higher shrink swell ratio, which locks sand grains together but you will need less of it (or you get too many cracks). To trst fpr clay content amd quality, take a small kneaded lump of clay about the size of a shooter marble between thumb and curled forefinger and try to extrude or push a ribbon out. The longer you can get it before it breaks the better and higher your clay content is (you can look up on web, I can't remember measurements but think two inches is a good high clay soil). Jar test is good but less reliable than extrusion methods supposedly, as some clay particles are so small that they take forever to settle out. I also agree test bricks are the way to go. We made some cob bricks with what I thought was too silty of a Western state soil, but they held up amazingly well out in the weather after a year (though we didn't get too much rain). Really good clay seals out water, which is why certain kinds are used to line landfills. Ok I will shut up now, soil is one of my favorite topics to discuss, and hardly anyone in my family wants to talk about it anymore. Monica Anyone looking for a good summer read could pick up "Hope, Human and Wild", by Bill McKibben on topic of resource conservation, voluntary simplicity, "less is more", etc. Example of Curitiba, Brazil, gives hope that urban areas can be more sustainable places
|