This is a kinda how long is a piece of string question, but...
we regularly make large precast concrete pieces and move them the next day, PSI after 1 day is around 3000.
However we treat these pieces very carefully, and chipping corners is a big concern. We use lots of polystyrene foam to...
Im also leaning toward restraint/thermal (restraint cracking is partly due to thermal change)
Was your mix design hot? by that I mean did you design it to reduce thermal issues? (slag,silica fume, cold water?)
Johnny at cast stone and precast concrete http://premier-stoneworks.com
