I have a particular problem with a damp basement in a new home. The floor seems to change color and darken in the center of the room and toward the walls.
The Housing and Cement Products Bureau of the Portland Cement Association, Old Orchard Road, Skokie, Illinois 60076, has published information on "Repairing Damp or Leaky Basements in Homes," which offers excellent advice on remedial measures that can be taken.