At 14:17 -0400 6/5/2003, Brent Walston wrote:
Perlite is the most common replacement for rock for lightweight concrete
(tufa?). However, and it is a big however, it greatly decreases the
structural integrity. So, you will want to incorporate some sort of fabric
or wire reinforcement and use a lot more support members.

I built lightweight concrete tops for my propagation tables about ten years
ago. They were fine until the wooden supports began to sag and rot, then
the tops collapsed.

I remember in the 70s there was a big fad on concrete hi fi speakers
enclosures (I kid you not!). The construction was based on small
gauge chicken wire as reinforcement and styro-foam beads as aggregate
(we all had bean bags, so they were freely available ;-) I'm not sure
how it would go as a material for flat sheets that laid horizontally
- they wouldn't take a lot of weight, I would guess. But as material
for hollow uprights? Hmm ...

Cheers

Rob

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