set in concrete

set (something) in concrete

To establish something firmly or permanently; to make something unalterable or not subject to change. The healthcare law looks promising, but we'll have to wait until Congress sets it in concrete before we know exactly what it will do.
See also: concrete, set
Farlex Dictionary of Idioms.

set in concrete

If a plan is set in concrete, it is fixed and cannot be changed. With expenditure plans now set in concrete for three years, slower growth would mean higher taxes. Note: You can also say that a plan is cast in concrete. But the sale conditions must be cast in concrete.
See also: concrete, set
Collins COBUILD Idioms Dictionary, 3rd ed.
See also:
  • (I) wouldn't (do something) if I were you
  • a/the feel of (something)
  • a straw will show which way the wind blows
  • a crack at (someone or something)
  • a fast talker
  • all right
  • (you) wanna make something of it?
  • all for the best
  • (you've) got to get up pretty early in the morning to (do something)
  • a thing of the past
References in periodicals archive
In fact, memories and perceptions seemingly set in concrete can prove surprisingly malleable.