History Lesson for all Concrete Contractors:
Do as the Romans do they say right? I guess now us Italians have some bragging rights considering the Romans were far beyond their years in engineering concrete.
How did the Romans build concrete structures in harbors along the central Italian coast that have lasted thousands of years, while today’s concrete rarely last more than a few decades? The reason is because the Romans invested heavily in designing concrete that could endure earthquakes, remain resilient to corrosive seawater and hold its form even without steel support. They designed the seawater concrete so successfully that it “can neither be dissolved in the waves, nor by the power of water”
Roman concrete is made of volcanic ash, seawater, lime and lumps of volcanic rock. When first laid, chemical reactions would occur between these ingredients and form new substances, including a rare mineral called tobermorite a 2017 study suggests. Intriguingly, whenever a crack appeared in the cement, more tobermorite crystals seem to form and patch the crack, which all of us sidewalk concrete contractors could definitely could use today (Haha)
The Roman concrete depended on rare volcanic ash, making widespread replication difficult. Even so, the finding offers us a new way of looking at concrete: whereas the modern stuff is designed to harden and never change, the Roman approach would produce concrete that effectively heals itself. By finding a material that imitates the Roman ash, we could build structures that would withstand the test of time.
The one con of Roman concrete is that it does takes time to develop strength from seawater, and features less compressive strength than typical Portland cement. For those reasons, it’s unlikely that Roman concrete could become widespread, but could be useful at specific locations and concrete structures.