TIP: Mixing Vermiculite Concrete Tools, Tips and Techniques Discuss TIP: Mixing Vermiculite Concrete in the Pizza Oven Design and Installation forums; Wiley, I had so many bags of vermiculite that I wasn't really keeping count when making the oven complex, but ...

[cvdukes]

Wiley,
I had so many bags of vermiculite that I wasn't really keeping count when making the oven complex, but I starting getting concerned about quantity when doing the pool bottom. About Halfway through, I figured I was getting about 3 cubic feet out of a bag and had to adjust my depth accordingly to make sure that what I had covered the area. Then at the end, I ended up with 7 bags left over, so thought that maybe they were about 3 & 1/2 feet.

I noticed they were actually packed by weight and not by volume... I think there is a lot of settling, plus the act of mixing compresses out the air spaces...

[Padilley]

Wiley,

I just mad concrete using 4 cubic feet of vermiculite and .6 cubic feet of portland and filled 16 sq. ft. 3" deep. That works out to 4 cu.ft.

[Neil2]

"For the pool vermicrete, I could have borrowed a neighbor’s concrete mixer"

I found that using my concrete mixer tended to "break down" the vermiculite particles. This made for a higher density - not as good for insulating. I now mix it by hand using a small garden shovel and wheelbarrow.

Also consider adding perlite (large granules). This seems to improve the workability if you are using a screed to archive the dome shape.