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tel jetson
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anybody know if sodium silicate qualifies as a pozzolan for making hydraulic lime out of regular slaked lime?
 
Gary Olsen
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My limited knowledge about pozzolans does not address your question.

A pozzolan, from my experience, is something which will aid the cementitious chemical process. Fly ash, sodium silicate and kaolin clay are pozzolans and will strengthen concrete while reducing the portland ratio to aggregate.

Hydrated lime is used in plaster. IIRC, it delays the set up time.

What are you trying to do? Are you just trying to make hydrated lime?
I don't know much at all about plaster.
I say play with it. Give it a try.
Gary
 
tel jetson
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I'm wanting to use hydrated lime to stabilize rammed earth walls. I was told a while back that hydraulic lime would work better than hydrated lime, but my attempts at getting the local supplier to sell me less than a pallet of hydraulic lime failed miserably.

these walls won't be bearing much load (if any), so failure wouldn't really be a huge disaster. all the same, I would like them to last. they will also be in contact with moisture, which also suggests to me that hydraulic lime might work better.

some of the literature I've read suggests that the clay in the rammed earth mixture might act as a pozzolan, but I'm not at all sure about that. might, as you suggest, just be a matter of trying things out.
 
Gary Olsen
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You want to use hydraulic lime to stabilize rammed earth walls! Are the walls already in place? If so, I don't think the lime will stabilize the whole wall. My first instinct is that it would need to be mixed with the rammed earth prior to ramming.
 
tel jetson
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Gary Olsen wrote:You want to use hydraulic lime to stabilize rammed earth walls! Are the walls already in place? If so, I don't think the lime will stabilize the whole wall. My first instinct is that it would need to be mixed with the rammed earth prior to ramming.


haven't built them yet. I will certainly be mixing the lime in before ramming. I may lime wash the exterior, too, but this particular query is about mixing in lime before ramming.
 
Eric Thomas
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Location: Northeast Oklahoma, Formerly Zone 6b, Now Officially Zone 7
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No, a pozzolan is a supplemental cementitious material, something that will hydrate in the presence of calcium hydroxide and act pretty much like Portland cement. Fly ash, pulverized slag, pumice are all pozzolans. Sodium silicate will react with the unhydrated cement in concrete and form a crystal that will fill the gel pores, effectively sealing the concrete. That's typically what it's used for after the placement of the concrete and initial cure, as a sealer and densifier.
 
tel jetson
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Eric Thomas wrote:Fly ash, pulverized slag, pumice are all pozzolans.


these are all largely silicon, which is why I wondered if sodium silicate would also work as a pozzolan. I've gathered by now that it will not.

after reading a bit more, I'm no longer convinced that I need to approximate hydraulic lime for this project. I think hydrated lime could work just fine. or no stabilizer at all, as the walls in question will be fairly low and not load-bearing.
 
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