Waterproof polyurethane glue is used to bond outdoor stones together to create landscape features with small to medium-sized rocks. Polyurethane glue can bond concrete, glass, metal, stone, wood — ...
Polyurethane glue can bond concrete, glass, metal, stone, wood -- pretty much any sort of material you'd use outdoors. Plus, it's waterproof and won't break down when exposed to harsh weather.