You are essentially painting a concrete floor after all.
Damp proof membrane in concrete floor.
A damp proof membrane dpm is used to create a barrier between a concrete or screed subfloor and the floor covering that is laid on top such as wood ceramic or quartz tiles laminate or carpet.
Assuming that the damp proof membrane dpm under the concrete has failed in areas then yes you possibly would get the odd patch of dampness showing in the floor.
This barrier is intended to stop moisture passing from one to the other.
There are however two options for damp proofing concrete floors without needing to replace the floor itself.
Either a damp proof coating can be applied to the surface of the concrete or a damp proof membrane can be laid on top of the concrete.
The easiest solution for damp proofing concrete floors is to install a plastic membrane.
But it is an effective way to do it.
Essentially this is a plastic mesh sheet specially formulated to ensure that moisture cannot penetrate.
If there was no dpm i would suggest a uniformal distribution across the whole floor.
The epoxy dpm comes as a two component system.
You also mentioned that there are vinyl tiles over the floor.
A damp proof membrane dpm is a membrane material applied to prevent moisture transmission.
Once the liquid membrane has been applied to the concrete and it dries an extremely hard surface is created that is impenetrable for damp.
A liquid epoxy damp proof membrane dpm is often used as a remedial solution where an existing dpm has failed or was never installed.
A liquid applied dpm damp proof membrane is a simple solution and an excellent way to damp proof a concrete floor.
It might seem a bit unusual.
Typically a dpm is a polyethylene sheet laid under a concrete slab to prevent the concrete from gaining moisture through capillary action.
Inserted in between the hard core and concrete floor this impermeable layer will prevent rising damp.
If in budget you should look at getting a new concrete floor poured.
Damp proof membranes for concrete i know we re repeating ourselves but a damp proof membraneis one of the most fundamental methods of sealing a damp floor.