I believe I have read that sandblasting is not a good thing to do to Portland
Cement. You may want to jump up on ferroboats and read up.
I know I saw some pretty bad results from someone who did that to a Ferro
boat several years back. I saw exposed mesh and numerous spots that had to be later faired again.
Apparently sandblasting is very abrasive and Portland
is not very resilient.
If you google
"sandblasting concrete" all the articles talk removing ingrained dirt and debris. That sounds pretty agressive.