TIL Roman concrete recipes vary by region after digging through a site in Bath

So I was volunteering on a dig near Bath last summer, and we hit a section of what looked like a Roman bathhouse foundation. The concrete there was super different from what I'd seen in textbooks for Pompeii layers. I got curious and started comparing samples from a few sites across the UK and Italy. Turns out, local materials like volcanic ash or crushed pottery changed the mix a lot depending on what was available. I even noticed some spots had lime mixed in weird ratios compared to others. It made me rethink how standardized Roman building really was. Has anyone else run into regional variations in ancient concrete or mortar from different excavation sites?

2 comments

2 Comments

william_henderson18d ago

Heard a similar story from my buddy who was on a dig in Turkey, said the Roman concrete there had crushed seashells mixed in instead of the volcanic stuff you see in Italy. Totally changed the color and the way it crumbled over time.

allen.ivan18d ago

Nah, seashells were just cheap filler, volcanic stuff held way better.