Vermiculite/Mortar mixing formula for insulation?

[bimmerFAITH]

Anyone know proper vermiculite/mortar mixture for flue liner insulation? $67 seems high for a 45# bag. I can't imagine vermiculite is very expensive by itself and would rather just mix this stuff up rather than pay someone else to do it.

 

[super3]

6:1 was what I found for chimney insulation. Mix it together dry then add water. 4 cu/ft bag at the local lumber yard or brick supply was $9.95 but, it was very fine.If you wanted the large expanded you would have to buy a whole skid.

 

[MrA]

plant nurseries use it.

 

[Chris-PA]

Good info - I generally mix my own mortars but I have not tried that yet.

 

[blackdogon57]

Ask a local pool installer. They use a ton of vermiculite for pool bottoms.

 

[freemind]

I poured fireproof concrete, when I made my forced air OWB.

It required portland cement, vermiculite, and perlite.

50% portland cement to 50% verm./perlite mix (80% vermic to 20 perlite)

Mix dry, then add water SLOWLY.