• KairuByte@lemmy.world
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    18 hours ago

    I feel like none of these things will actually weaken concrete, unless it’s being added to the concrete mix itself.

    • FiniteBanjo@feddit.online
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      17 hours ago

      The concrete is actually highly acidic but the outer layer cures to become alkaline and the two layers together end up becoming water resistant, so by adding acid to the surface it can lose its water repellent capability and weaken faster.

      If the concrete were sealed with a wax or an acrylic then Acetone would also be effective.

      • fullsquare@awful.systems
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        13 hours ago

        concrete is calcium carbonate and silicate, both are basic. it’s also slightly porous but mostly waterproof by itself, doesn’t matter that hard in this application since there will be AC removing water from the inside 24/7 anyway

        • FiniteBanjo@feddit.online
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          7 hours ago

          Carbonation causes acidity and the traditional methods of creating concrete involves furnaces which introduce various forms of carbonation. The Calcium Carbonate once dissolved in water will start to form the Calcium Hydroxide layer on the surface, thats the alkaline layer, and deeper in the carbonation creates acidity.

          • fullsquare@awful.systems
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            6 hours ago

            calcium carbonate is still basic and even hydrogen carbonate is basic enough to be protective against steel corrosion

            The Calcium Carbonate once dissolved in water will start to form the Calcium Hydroxide layer on the surface, thats the alkaline layer, and deeper in the carbonation creates acidity.

            100% wrong, how come there’s more carbon dioxide inside than outside, you’re starting from calcium hydroxide and silicate. on the surface there’s some carbonate formation from carbon dioxide, but when it can’t get there calcium silicate forms instead. either way both are basic

            • FiniteBanjo@feddit.online
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              2 hours ago

              Well, now you’re contradicting yourself from earlier when you stated we were discussing Calcium Carbonate and Silicate.

              The Calcium Carbonate degrades into Calcium Oxide. Calcium Oxide will form Calcium Hydroxide on the cured surface.

              The only reliable way to seperate the Calcium from the oxidation afaik would be the introduction of Chlorine, so you’re definitely not seeing the reverse happening regardless of how much carbon dioxide there is.

      • KairuByte@lemmy.world
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        17 hours ago

        Oh really? I honestly never considered that possibility and always thought of concrete as a kind of inert “stone,” I find this legitimately interesting.

        • Rioting Pacifist@lemmy.world
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          14 hours ago

          My understanding is that the genius of such attacks is they don’t actually have to do the damage but if there’s the fear of chemical damage you don’t want to build the rest of a building on top of it.

          • CADmonkey@lemmy.world
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            6 hours ago

            This right here is the answer. The possibility that the concrete cure was all or partially disrupted can mean the concrete has to go away and be re-poured.