I live in PA. We had the coping bricks around our pool repaired 3 years ago. After the first winter we had cracks in many of the bricks. After the second winter small pieces were chipped off. And this year the whole front of some of the tiles were broken off. Is this normal?? And yes we have mastic in the joint. What else can we use? This has been an ongoing issue since the pool was installed 9 years ago.