Phil Stevens wrote:Hi Trish -
Ash is one of the most common pozzolanic modifiers for lime. Adding wood ash to lime mortar or plaster makes it harder and more waterproof (hydraulic) than the lime on its own would be. Other additives that do similar things include volcanic ash, fired clay or brick dust, and silica. The famed Roman cements that have withstood weathering and even marine environments for 2000 years are made of lime and volcanic ash. I've done a fair bit of bricklaying and plastering with wood ash modified lime mortars and plasters, and I like the way they stiffen quickly, take a steel trowel finish for a tough "skin," and are able to handle exposure while they're still curing.
So, mixing lime putty with wood ash will definitely give you a trowelable mixture that will harden up nicely. I don't know how much insulation value it would have, but if you incorporate sawdust or straw,to give it tiny voids or air pockets, it could do what you want. Try some test mixes with varying proportions and see how they work...I'm curious too!
Glenn Herbert wrote:To get the best combination of properties, you might try a thick layer of the lime/ash/etc. mixture with lots of straw or sawdust, left rough for good tooth, and a finish coat without the insulating additive.
Glenn Herbert wrote:" All I can say is to try small sections of various combinations and see how they feel and hold up, before doing the whole floor.
Phil Stevens wrote:When I'm doing a lime plaster as an exterior finish, I add around 2-5% by volume to the mix of lime putty and sand and I may have tested up to 10 when I first experimented with pozzolans. "
Right, going to test with various loads of ash and try see what happens. Will keep you updated - plan on making some smallish tiles sort of thing to see what effects.
Lime putty is just hydrated lime that has been mixed with water and allowed to sit. The longer the better...if you've got a barrel that's been sitting around that's fantastic.
thomas rubino wrote:Hi Trish; I see what you mean about falling in love! That floor in the photo is OUTSTANDING! I hope that it works for you ! Keep us posted!
Glenn Herbert wrote:
You might be able to use strips of foam 10-20cm wide with a couple-few cm of solid grout between them, giving a rigid base so boards can't flex. That would be less insulating than continuous foam, but much better than none. In this case, I might use 2 or 3 cm thick foam. I would run the foam perpendicular to the topping boards so all boards have rigid support at close intervals.