eli5: why you need to water concrete for first couple of days?

Question

Why do they say to water walls of newly constructed buildings? This is mostly for the brick walls constructed by using cement for first few days.

EDIT: they say it increases the strength but I never understood how does it happen.

In: 1

Answer 1

Concrete does not “dry”, it “sets” via a chemical reaction that uses up water and binds it into a new chemical compound. That reaction is even called “hydration”. If there is not enough water, the reaction will not go through, and concrete will be weaker.