How are structures that are constantly in contact with water repaired or maintained? I imagine there has to be some sort of preparation or specific process for this?
In: Engineering
Some common, but incorrect/misleading ideas about concrete here.
1. Concrete needs water to cure. The water is already in the concrete when it’s poured. This is all the water the concrete needs. When you cure concrete you mostly need to make sure none of the water already in it evaporates from the surface during curing or you’ll get cracking. There are several ways of accomplishing this – some involve keeping the concrete wet, others involve putting a waterproof membrane over it to stop evaporation.
2. More water in the mix =/= stronger concrete. The exact opposite. When you look at concrete mix designs there is typically a straight line of strength loss as you add more water to any given mix. If you want strong concrete you (simplified somewhat) put as little water in as possible while maintaining workability (more water = more flowable concrete = easier to pump, place and compact, but weaker compared to an otherwise equal mix)
3. U/timster1 is correct about the crystalline waterproofing admixture. This works pretty much as they describe. There are some other admixtures they can use also when there’s reinforcement in the concrete. They can also work with other aspects of the mix design – cement content, air entrainment (tiny microscopic air bubbles that allow stress relief to prevent damage from freeze thaw cycles)
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