Titebond III is a PVA wood glue and has nothing to do with concrete. It is water resistant when dry not water proof. It should not be used as part of a water feature where it will be in constant contact with water.
If you want to properly seal something that will be in or around water constantly you should use drylok as it is actually waterproof.
Originally Posted by FrogTim
Most people use TB3 to coat GS in the portions of their water feature. It is similar to a concrete paste. It is great for sealing/texture, but not so great to create 3D shapes like Great Stuff. You can also coat other areas of the hardscape you want to seal or add texture to like branches, pvc pipes, rock waterfalls, etc.
If you are using GS I too recommend the black 'pond' great stuff because it doesn't show through like the yellow normal kind.