Does concrete need water to further harden in the years after it is poured?

concrete is said to gain it's 90% strength in the first 28 days itself.it might continue to strengthen for decades to come after that.but the water that is already mixed with it previously dries up and is not present.so i think the moisture from the atmosphere must help in the hardening.
correct me if i am wrong 😀

it will set-up better when kept wet, i work in a lab testing concrete cubes and we keep them under water for seven days to cure for a strength test,, this is suppose to get them to max. strength

The procedure for concreting is exothermic reaction as it exerts heat energy continuously water is just play a role to maintain the moisture content of concrete, water using for curing is just maintain the moisture of the concrete to acquire its ultimate strength in the given time period to make the structure strong.
we can also say that water is the major factor which accelerates the hardening of the concrete by providing required moisture to hydration process, which is exothermic. Concrete exposed to water contact periodically will have more detrimental effect to its life.If you take a sample of the 6 or 7th year and 10 or 12th year concrete core you
will find only fractions of difference which is again very negligible.