“How Long Will It Take My Cement To Dry?”
“Only…. one slight snag, cement is not used on its own, and is only a part of two materials we might use. One is Mortar and the other is concrete.”
“OK then, how long will it take my concrete to dry?”
“Only…. one slight snag, concrete doesn’t dry. Not in the sense that you mean it.”
“OK then, how long will it take for my concrete to go hard then ?”
“Once you have mixed cement and sand, or cement, sand and stones with water, and the contents are thoroughly mixed together, something unexpected happens.
A chemical reaction takes place which causes the cement to crystalize. And as it does so the water component of the mixture becomes a part of the overall structure, and helps bind the sand and the stones together. This ultimately results in a solid mass. Interestingly, this chemical reaction generates heat. Freshly laid concrete can often be seen giving off steam on a cool day.”
“Yes, but…. HOW LONG DOES IT TAKE ?”
“Freshly mixed mortar or concrete goes into its initial set after 20 minutes, after which it should not be re-positioned, and into its final set after 40 minutes.
It can still be easily broken apart at this point, and should be allowed to rest as it is for up to 24 hours undisturbed so that there is no risk of weaken its structure.
It’s important for this reason not to walk upon freshly placed paving slabs or lean against freshly placed bricks or blocks. Slabs which have just been placed generally only sink because they have been walked upon much too soon.”
“OK…. I was just curious ……”