Re: Concrete subs?

[John Brownlee <jonnie@chronic.lpl.arizona.edu>]

	This is an interesting idea for sure. The concrete used in this
application is not exactly stock; I remember something about the addition
of microspheres to decrease the density. Also, the permeability/porosity
of concrete was supposedly a limiting factor, particularly under high
hydrostatic load. Remember, it isn't just how porous a material is, but
how well connected those pores are. Much effort has gone into developing
concrete mixtures which overcome this, I am sure several commercial
mixtures are available for the truly interested.
	Although for subs specifically concrete may not be an answer, I
would guess that for submarine habitats it might be really ideal,
providing some of the formentioned unfavorable qualities of the material
can be overcome. 

							John

John Brownlee
Lunar and Planetary Lab
University of Arizona
jonnie @ lpl . arizona . edu