These are insulating castables
with some bulk density which is generally lower than 1.6 g.cm-3.
By using light weight aggregates such
as Perlite, Vermiculite, Expanded
Clay, light weight chamotte
and Bubble Alumina, concretes with low thermal conductivity
for insulation applications
either in hot faces or back up linings are formulated.
In these castables, binding is
based on calcium aluminate cement hydration.