Bendy roads disaster

If the Tuzkhur valley game is to be four tables in length (that was my initial plan) I'll need at least 24 feet (7.3m) of roads.  So I decided to do some roads made from foamcore.  I can get quite a lot from work (design companies tend to use it for mounting proposals and after you've decided which set of designs you like you're left with acres of the stuff).

I cut 12 feet of road sections with chamfered edges and then painted them with textured exterior masonry paint for that gritty, tarmac effect.



Sadly, they all warped, turning into attractive, but useless, smily shapes.  

I shall persevere for a bit - it's worth getting some experience with the materials and I might be able to save them but it looks like I may be on the scrounge for road sections as the day grows nearer.