These add greatly to the stiffness and protect the ends from moisture and dings. It has no evidence of any damage from moisture or from being taken here and there on a regular basis. Since my father is V.P. of a local concrete company, I have some first-hand experience with the concrete form tubes. The can be made to work quite well as telescope tubes for instruments under 13 inches in aperture, providing certain things are done to them. Large gaps in the paper windings also should be sealed with a good filler.
Some people even use decorative adhesive wall paper material on the outside.
They are cheap and easy to work, so I can recommend them. Clear skies to you. However, it does make the scope take quite a bit longer to cool down. Back to Tallahassee Astronomical Society's home page.