Sientists have long puzzled over the elusive recipe for ancient Roman concrete, which has withstood the test of time better than any of the concrete that’s been poured in the 20th century. Now, Time reports that Maria Jackson from the University of Utah claims to have unravelled the mystery, and furthermore believes that the ancient Roman process could influence modern-day construction.

Jackson’s findings, published in American Mineralogist, claim the unbreakable strength of ancient Roman concrete is due to a rare chemical reaction that takes place when the mineral aluminium tobermorite is exposed to sea water. The reaction strengthens the mortar and prevents cracks from forming or widening.