Any soft or medium density limestone can suffer from frost heave when used externally. This is a process that occurs over time. When rainwater collects on the top of the stone it can perforate into small cracks / features in the stone tile. When this water freezes it expands and therefore can cause pieces of the stone to flake away from the surface.
Choose frost resistant stone for outside
Therefore it is very important to only use a frost-resistant stone externally. Granite and slate are frost-resistant. Hard limestones such as Yorkstone, Belgian Blue, several of the Egyptian limestones (Dijon Tumbled, Aged Melbury and Brushed Wilton) and the hard Indian limestones (Aged Chalgrave, Aged Farley, Aged Lambourne and Aged Chalgrave Blue) are all good choices.
Terracotta and Travertine are not frost resistant and should not be used externally.