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Concrete does have capillaries, and a good example of this is older bridge deck designs, whereas the deformed metal bars(rebar) placed in the concrete slabs, were not coated with epoxy, stainless steel, or negatively charged, ( there was actually a design that involved something along those lines to mitigate corrosion, I forget the specifics on how it functioned). The rebar years ago was often placed too close to the surface and the salt used in the winters would be absorbed into the concrete, react with the unprotected steel and corrode. The rebar would corrode and expand like 6 times it's diameter and spall the concrete apart. It was a big problem in NY years ago. The expansion properties of rusting steel is amazing, the building I was working on today is 1940's era masonry, with heavy steel lintels spanning the piers that create the old storefront, the lintels look like someone went along with a big pry bar, some are rippled, deformed, all due to the rust flakes putting pressure, point loaded and noticeably expanded small humps in the steel flange that was once straight. Poor design, the soldier course of brick above and the steel creates a joint, one that was never sealed or caulked, 60 years later, it's a mess and will eventually require some serious remdial work to correct. Concrete finish products like Lapidolith and Euclid chemical company are used for many applications, I think they manufacture sealers as well, I used to review quite a bit of contractor submissions of concrete accessories, for job approval or rejection, according to project specifications. Most of these and other products require the concrete to have cured the full 28 days prior to applying, something to remember. Pharmaceutical manufacturing facilities are one example where I would think that would have stringent finish requirements for concrete slabs, and or industrial type flooring like epoxy bonded to concrete, due to the nature of what they do in these buildings.
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