Hi Jess1485 I'm going to suggest the use of a normal lime scale remover of the type in any supermarket - Viakal, Limelite, or similar. Just spray on and leave to work. Any product that works with scale should be able to soften cement to some degree, and must be worth a try. Another product that may work is distilled vinegar.
There are more powerful products out there, but their use may involve some danger.