This project is all about how well you prep your surface.
Is it newly poured cement?
Did you etch the cement first before applying the Paint?
What paint did you use? Is it specifically for cement?
What temperature was it outside when you did this? If it's too cool it will not dry.
If the temps are too hot and humid, it will take a really long time to dry.
Did you follow the product directions to the T?
All this will hugely impact your final result and without knowing this info, I can only guess at this point.
