Hi Alex!

What a coincidence, I just finished writing about Roman concrete in my newsletter! It'll be published next week!

As far as the carbon dating of puma punku stones go, I don't think there's been any conclusive results. At least not that I've seen.

All I've found is this paper from 2013 that carbon dated the "layer of blackened earth at the top of the massive clay-fill layer that was laid down early in the Pumapunku's construction history, [which] yielded a calibrated one-sigma range of AD 542–593."

Here's a link to it if you're interested: https://www.academia.edu/36448246/A_Radiocarbon_Chronology_of_the_Pumapunku_Complex_and_A_Reassessment_of_the_Development_of_Tiwanaku_Bolivia

I hope it helps!