We tend to imagine ancient materials as crude or primitive, but Roman concrete was more sophisticated than anything in use until the modern era. Our current concrete recipes use cement, sand, and coarse aggregates in varying proportion and are, by comparison, extremely carbon intensive. This is where Roman concrete becomes more than a historical curiosity. Roman concrete contains ubiquitous white crystals called lime clasts, formed by quicklime mixing at high temperatures. This is a rare positive feedback loop: more valourised waste, less aquatic pollution and reduced carbon footprints in construction.

Source: The Irish Times December 11, 2025 16:32 UTC