This site gives some volume/weight conversions. http://www.diydata.com/materials/cement/cement.htm ----- Original Message ----- From: "Amanda Peck" <ap615 at hotmail.com> <snip> > I'm NOT a structural engineer. Someone who is MAY be able to tell you > easily. (Does anybody know off-hand about relative weights--concrete, > stone, cob? I know there's a lot of "it all depends" in there.) <snip>