I'm sure they can analyze a sample of 2000 years old concrete, but it's not going to look the same as when it was built and it'll probably not be a simple mix o

I'm sure they can analyze a sample of 2000 years old concrete, but it's not going to look the same as when it was built and it'll probably not be a simple mix of basic elements but very complex. The Romans might have used a mixture with actual lava or corals e.g. and it'd be hard to trace it back to such ingredients.