Roman concrete gets stronger in seawater, ours doesn't

Roman concrete gets stronger in seawater, modern concrete crumbles. Ancient Romans mixed volcanic ash, lime, and seawater, creating a reaction that forms rare minerals Al-tobermorite and phillipsite over time. University of Utah analysis of 2,000-year-old breakwaters at Pozzuoli showed the concrete still hardening. Our Portland cement needs steel reinforcement and fails in 50 years in salt. Roman harbors are still intact. Scientists at MIT and Berkeley are now copying the recipe to make greener, longer-lasting concrete that actually heals cracks by growing new crystals when exposed to water.