Caliche: calcium carbonate formed in the soils of semiarid regions.
“I sifted the caliche through a chicken wire sieve to get rid of the larger material. This leaves a good size aggregate for a 4-5inch think pour, thicker floor better against moisture too (when the pour is too thin less ,than 3″, the mix will crack more, when setting). I used string lines leveled with a bubble level for strings to keep the floor level (you can see it in one of the pictures). It starts drying very fast so its good to go by sections that are at arms length to burnish with a trowel as it hardens. This gives it a nice smooth finish, though a little rustic since it is not floated first with wood guide rails the way you would a concrete pavement. (this was easier for me since I was working on a round floor plan). As it dries keep an eye on it as it will develop cracks, just proceed to burnish over the cracks constantly and it will all even out as it sets completely. The caliche mixed with cement is not grainy like sand and is easy and smooth to burnish as if it was pure hydrated lime. Finally, I sealed it after a few weeks with a clear cement sealer (boiled linseed oil, is too expensive here). No rebars. The ratio is 4 five gallon buckets of sifted caliche to 1/2 bag (a 50kilo bag) portland cement to 1-1/4 five gallon bucket of water. The mix sets better if poured not clumpy but soft to very soft. Old edges blending into newly poured edges takes a little extra burnishing. All in all was SO EASY, no ramming.
Keep in mind this floor is set on a base of filled tires that is topped off with compacted gravel [you don’t need the tires], then a thin layer of caliche ramped then the poured floor. This gives me about 14″ above grade. One floor in the smaller dome is only 2 months old. We are already in our rainy season and the floor is damp free. Caliche all around is better than anything here in the tropics against moisture problems. I built a 15′ diameter dome with clay and found it to be terrible with cracks. I then switched to road base then caliche and caliche unstabilized in the poly bags are superior in ramming and moisture retardation.
Things i would recommend.
1. A vibrater [plate tamper?]. This would get rid of the cracks when setting.
2. A bull float for burnishing instead of a trowel. This is a metalic float attached to an extremely long arm used in floating large areas.
3. Cement coloring [iron oxide pigment]added at the mixing stage. It would work well as caliche absorbs the powdered color and would give a nice worn look.
3. Wooden guide rails to give an even leveling when pouring.
4. Tile pattern could work with this if you have the forms as described in one of Owen’s earthen floor solutions.” See Eleven Earth Floor Methods