system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does a spinning drum of concrete keep it from hardening?
gpt
It doesn't.

If you're wondering why cement trucks rotate their drum it is to keep the contents well mixed. Continuous mixing helps delay setting by not allowing any one part to get drier than the whole mass. It will still harden eventually though no matter how much you mix it.