– How does leftover cement in cement trucks not harden and slowly accumulate in the mixer, essentially clogging it?

Question

Title says it all; I’m sure a thin layer of cement will be left over after they poor it all, and I would imagine that thin layer would harden and then the next time they use the mixer another thin layer would be leftover and so on and so forth. After a while I would imagine it would accumulate to the point where it renders the mixer unusable.

Why is this not the case?

In: Engineering

Answer 1

You’re on a clock from the second you add water to cement or concrete.

The answer is they get it all out before that happens and then wash out the drum.