metalresearcher - 7-9-2014 at 05:29
I have been using this excellent construction material for high-temperature lab applications although not designed for this, including metal melting.
It withstands temperatures till 1350C for at least 10 re-uses.
https://en.wikipedia.org/wiki/Autoclaved_aerated_concrete
I am curious what is is made of. Al2O3 or CaO ?
careysub - 7-9-2014 at 16:17
Addressing aerated autoclaved cements generally, not that one product:
It no doubt has variable composition - like concretes/cemenets generally, since it is really a processing method rather than a formula.
Here is one vendor, and even for this one product the proporations at least seem variable:
http://www.csr.com.au/Our-Products/MSDS/Hebel%20Autoclaved%2...
Predominantly calcium silicate hydrate, with a substantial admixture of crystalline silica (aka sand), and goodly portion of portland cement, which is
itself a calcium silicate cement.
[Edited on 8-9-2014 by careysub]
markx - 8-9-2014 at 01:54
AAC is made by first mixing portland cement, gypsum, milled sand, hydrated lime and aluminium powder with water to form a liquid slurry. Depending on
formulation a number of other fillers, binders and modificators may be added (e.g flue ash, blast furnace slag, milled limestone, thickeners,
superplastisizers etc). This mixture will be cast into huge block type molds where the aluminium powder starts to react with the alkaline components
and releasing hydrogen gas. This process will expand the mixture and give it the porous bubbly structure that we all know. In about 40minutes the mix
has expanded and set to a preliminary strenght. The mold is dissassembled and the resulting slab is cut into blocks with wires. These heaps of blocks
will then be further cured in a steam autoclave at high temperature and pressure (I can't recall by heart but in the order of 200C and 10atm), this
steam treatment will cure the blocks and give them the final strength and durability.
PHILOU Zrealone - 8-9-2014 at 07:36
Other asset, aside from bad heat transfert (good insulation due to bubbles) is the resistance of the material to static or slow increasing pressure
(not to shock!) .