Scott & Egon: What you are seeing with the concrete is a slow-moving chemical reaction called efflorescence. Water can migrate from one side of a slab to another. The water reacts with the lime in the cement, and ultimately moves through the concrete, molecule by molecule.
My lab at General Dynamics in San Diego was housed in concrete block buildings erected in about 1955. We had a severe problem with this effect, since the reaction would cause the interior latex wall paint to blister and flake off of the walls. Any exterior wall would create a little ridge of dust on the floor. I don't know what the effect of this constant process was regarding strength of the blocks, but the building did last for forty years. There's no way to stop this on the inside (drier side) of the wall. You have to seal the outside surface to prevent the water from getting at the concrete. I'm not a civil engineer either; indeed, my wife assures me that there are no civil engineers. :-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-) Ed Price [email protected] Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 619-505-2780 (Voice) 619-505-1502 (Fax) Military & Avionics EMC Services Is Our Specialty Shake-Bake-Shock - Metrology - Reliability Analysis :-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-) > -----Original Message----- > From: Egon H. Varju [SMTP:[email protected]] > Sent: Monday, August 23, 1999 10:25 AM > To: EMC-PSTC > Subject: RE: Concrete as an insulator??? > > > Scott, > > At 05:34 AM 23/08/1999 , you wrote: > >I would beg to differ on your comment that "Once the concrete is set, > there > >is very little, if any, water absorption". I have water wicking through > the > >concrete floor in my basement quite regularly. Having seen the salts that > >are washed out of the concrete by water wicking through tells me that > >concrete really does absorb (or pass) water. The only way to stop that is > >to seal it somehow. > > Well, maybe so, but what this tells me is that you should have found a > better contractor. And if there really is salt leaching out of the > concrete, then you have a major structural problem, since your rebar will > be completely rusted out by now. This is not a very unusual problem, > since > shady contractors can save a few buck by using beach sand for the concrete > mix. > > I seem to recall a building collapsing recently in Mexico because of cheap > > beach sand. > > Disclaimer: Like I said before, I'm not a snivel engineer. > > Regards, > Egon :-) > > __________________________________________ > > Egon H. Varju, PEng > E.H. Varju & Associates Ltd. > North Vancouver, Canada > > Tel: 1 604 985 5710 HAVE MODEM > Fax: 1 604 273 5815 WILL TRAVEL > > E-mail: [email protected] > [email protected] > __________________________________________ > > --------- > This message is coming from the emc-pstc discussion list. > To cancel your subscription, send mail to [email protected] > with the single line: "unsubscribe emc-pstc" (without the > quotes). For help, send mail to [email protected], > [email protected], [email protected], or > [email protected] (the list administrators). > --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
