The recent events and flooding of Texas and Louisiana coasts are further evidence that sea levels rise and shorelines erode and our shores and coastal regions are continuously impacted by water. Two thousand years ago, Romans constructed vast sea walls and harbor piers. The concrete they used outlasted the Roman Empire and we still see evidence of that around us.
Today, the modern concrete that we use in our buildings could corrode within decades but the materials that the Romans used was a marvel of engineering according to experts and engineers. DuPont engineers have examined the material and believe that what the Romans built has been the most durable building material in human history according to an article published last month (July 2017) in the Washington Post and several other news outlets.
Therefore, the mystery is what the Romans made the ancient concrete from (what is the recipe) and how they made it. According to a scientific paper published in the Journal of American Mineralogists, a team of University of Utah scientists have examined the concrete and believe that the rocklike concrete behaves very much like volcanic deposits. Roman concrete is filled with tiny growing crystals. The crystals, like tiny armor plates, may keep the concrete from fracturing as the scientists report. The scientists subjected the concrete samples to a battery of advanced imaging techniques and spectroscopic tests. The tests revealed a rare chemical reaction, with aluminous tobermorite crystals growing out of another mineral called phillipsite. However, the big surprise was that the recipe needed a key ingredient and that proved to be sea water. The experts believe that as the seawater percolated within the tiny cracks in the Roman concrete, it reacted with the phillipsite naturally found in the volcanic rock and created the tobermorite crystals.
The question now is if we can learn from this study and what we have learned about the ancient Roman concrete and build better future concrete to protect our cities and shorelines.