When concrete "dries/hardens/cures" where does the water go?

Question

I don't think it just "drains out" but I would think it evaporates. If it does just evaporate, how, because of all the rest of the concrete? Maybe I'm just ignorant, but I would think if it does just evaporate, the outside edges would harden and seal the inside of the slab preventing it from drying/hardening/curing. Reason for asking is I have a complicated concrete project underway that I'm not going to go into details with and I need to figure out the best way to SLOWLY dry/cure it. Any concrete gurus please advise. Thanx!!

Answer 1

The water chemically reacts with the cement in a process called hydration - it stays in the product, and doesn't evaporate or drain away.  After the reaction, the cement "cures" into a hard substance.

After the concrete sets, keep it covered, especially in hot weather, to prevent water loss from evaporation.  Keeping the concrete wet by misting for a week after the pour will help ensure that adequate water is present for the chemical reaction to complete. Actually, the hydration process can continue for years, continuing to create a harder more durable product.

Answer 2

The water is absorbed through the chemical reaction.  It does not evaporate and the slab or whatever you are pouring will cure evenly.  If you are pouring in extreme heat you can use type 4 cement.  It has a low heat of hydration to resist premature curing from outside heat.

Answer 3

you are correct in the assumption that it evaporates...however it does not seal the water on the inside when the outside hardens.  despite the way it looks, concrete is actually a fairly porous substance...meaning it has many tiny tiny holes in it.  although the inside of the concrete does take much longer to dry, it does eventually completely dry out. I'd try to help you on the specifics..but i can't really do that without the details, sry

Good Luck with your project!

Answer 4

Concrete is porous and during the curing process, the excess water does evaporate off. To slow the water loss (will lessen shrinkage cracking), cure your concrete under water. Usually a curing compound is sprayed onto the concrete surface to seal it and slow the evaporation. You can also cure with water, either wetting burlap material laid over the surface, or by actually setting up a sprinkler system over the surface.