Funny just the other day I watched “ancient impossible” on cable, episode 8 was mega builds and they showed Roman concrete made with blood for water builds like piers and the aquaduct. The hosts were surprised that that concrete stood up to a a compression test to 400 psi when a good mark for modern concrete is 300 psi
It starts at about 4 minutes 30 seconds and I think they are at the CEMEX plant in Austin Texas
Those numbers are off by an order of magnitude. American Concrete Institute (ACI) cutoff for needing compressive strength testing for concrete is 2500 psi.
Side note- Cemex makes really good concrete, I’ve had several jobs of late where their product approaches or exceeds design strength on 7 day breaks (design strength is based on 3 sample breaks at 28 days averaged).
Corporately, I’m irked that they recently made to shut down the sand quarry down in Monterey. It’s a source of fine #3 sand with little need for processing and it was on patented land IIRC, so the state couldn’t shut it down on an eco-whim...