lovely work Chris... I've a thing for things n concrete.. havng helped a few guys build their 45' salboats from it.. and dong a bunch of fero concrete things.. like a non distructable playground for kids @ a NJ ..YM & YW HA
[ like a YMCA ] closet cacoon shower. and lots of free form sculptural things.. and lots with uses.. sinks.. showers..stairs. tubs... Any way.. there's a concrete mix called leak stop concrete @ HD & Lowes and sets up in a few mnutes.. [ not that it's of much use.. but it also expands a bit when it sets up.. rather than shrinking some... as the others do.. ] so.. give it a test run.. for something where settng up real fast is a help