Yo, listen to me.
You can't fill the PVC with cement because when you put pressure on PVC it is meant to absorb the pressure and flex a little.
It if it is filled with cement there will be no flex so it will create aton of resistance against the cement therefore breaking it 3x faster than normal. I've rollerbladed on my PVC rail for 2 months and it hasnt broken once, skiing itll work fine. Don't fill it with anything, itll break.
cement is retarded just screw it in.