MEDELMA@CMS.CC.WAYNE.EDU (Michael Edelman) (02/08/91)
From: Michael Edelman <MEDELMA@CMS.CC.WAYNE.EDU>
Thos Cohen asks "how long does it take for 36m of concrete to cure?",
with regards to Iraqi shelters. The answer: No longer than it takes
1m to cure.
Concrete doesn't harden through drying, but through a process best
compared to the production of rock candy :) . Kept wet, the crushed
minerals in cement (the portion of concrete which binds the mix) form
a number of interlocking crystals.
The difficulty in pouring really large structures- like dams- has more
to do with stresses set up in the uneven shrinkage and expansion in the
mix. A friend of mine who made his living as a rod-buster (that is, one
who built steel reinforcing structures used in concrete pouring) tells
me that this is dealt with via a combination of techniques involving
siad steel reinforcing, different concrete mixes and the like; it seems
his experience pouring nuclear reactor containment vessels employs
techniques similar to those needed in building underground shelters.
--mike edelman medelma@cms.cc.wayne.edu
hoover dam fan club medelma@waynest1