The low relative permeability of
advanced castables and the difficulty or increased care in baking out field
installations has led to the widespread and almost universal use of organic
bake-out fibers (OBOF) to increase permeability and aid in water release
especially in the critical dehydration range.
Figure 3 illustrates the trend of
low permeability of a low-cement castable and the increase achieved by the
use of an OBOF addition versus the normal permeability of a conventional
dense castable.