Since this is actually related to (what else?) the global warming hoax, it is only a matter of time before the Roman concrete ingredients are not only available, but required, all over the world.
Probably not for long, though-those same hoaxers will claim that the mining of the volcanic material-the tuff and ash-is somehow contributing to climate change and must stop.
Remember in the 70’s when they said we had to stop using paper bags because we were killing all the trees, so along came plastic ones-now they are insisting everyone use paper again, or those germ factory re-usable cloth ones.
Those people don’t know anything, so they just throw s*** at the wall to see what sticks...
Should be noted that the high energy component of Portland cement is expensive. Reducing it might make economic sense.
...and quintupled (at least) in price.