To end the confusion it should be made clear that ZONOLITE like QUIKRETE is a huge line of products sold around the world.

They have many vermiculites and perlites designed as concrete additives.

The one Paws wants to try however is a bit special and completely different from the vermiculite you buy from the garden centers.

Block filler ZONOLITE is treated to resist absorbing water so it could make an extreme light weight tufa and be more resistant to frost.

ZONOLITE brand vermiculite comes in fine grades specially designed for adding to concrete.

I ordered several all different to see how well they work for me.

If you are serious about making long lasting light weight Tufacrete products ZONOLITE is a line of products you should be considering.

PLUS they are generally cheaper than the ungraded lower quality garden grade products.:)

Here is a link that might be useful: Zonolite products