Looking for thoughts on a subject we can't seem to find much clarity on.
We're building a small-ish adobe in northern new mexico. 800 sq feet, two stories. We've dug a rubble trench foundation and per New Mexico code are looking at options for the 6" continuous/monolithic stem wall that will sit at grade on top of the tamped gravel fill. Most folks we've polled on this are quickly in favor of a concrete pour. We'd dearly love to avoid the concrete if possible but are hard pressed to find good info on other possible solutions. We do know stone to be the other natural-lovin' alternative, but for various reasons isn't viable for us here.
So, our idea is this:
We're already been working with some lime-stabilized mud (NM code again: the 4" above floor grade must be constructed of stabilized adobe) and have been very pleased with the strength and durability of the bricks so far. Is there any reasoning or considerations that should keep us from simply pouring our 6" stem wall from the stabilized lime mix we're already familiar with? [For ref, it's the traditional 70/30 sand/clay mix with about 7% hydrated lime, per volume.] We like that option for a few reasons. One, it keeps us from the concrete we're so loathe to use. Two, if it's good enough water-resistance to qualify as a stabilized brick, shouldn't it stand to reason it's also suitable for stem wall?
We'd love thoughts on a couple fronts:
Anything major we're missing in our understanding of the uses of lime? We've definitely read some fine work from IOM involving poured lime foundations, though here they're using quick-lime, and we're only familiar with standard Type-S hydrated lime. To our understanding, hydraulic (and quicklime applications) tend to be recommended for below-grade work, whereas hydrated lime seems to acceptable in all above grade applications.
We'd also love thoughts/direction more toward the logistics of a slab pour (lime mix or otherwise). Basically, whats a better approach for our form work: should we go for long, thin layers building upon each other until we've reach six inches in height OR working in small, short run sections, pouring the entire 6" height at once and then moving down the line. We know lime cures more slowly than natural adobe, but not sure precisely how long to expect this "slab" approach to the material to take.
We would love to hear thoughts from anyone who's used this method, for better or worse.
The advantage of concrete in the situation is that it works under all conditions. It meets all the needs required of it.
What is the objection to concrete?
Adobe, are you using it in brick form?
As for the slab, a mixture called 'limecrete' as used in Australia, and I believe elsewhere is a good material for the slab, it is best poured in one pour, no joins or layers.
An alternative is an earthen floor, and there is plenty of material about them around.
Good luck with the job.
John Daley Bendigo, Australia
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