The message
from Stuart Noble contains these words:

Maybe you could spray it with soda water to accelerate the initial set.

Joke not - It has been done! It works fine but the clients start
lookig suspicious

How about dry ice?

Supercritical CO2 has been used for hardening concrete. It's expensive,
so guess who gets to use it? Yup, the military!

--
Skipweasel
Pay no attention to that man behind the curtain.