Ancient Roman structures have survived for thousands of years.

Some have endured earthquakes, storms, seawater, and centuries of weathering.

Yet researchers have discovered something even more surprising:

Some Roman concrete appears capable of repairing its own cracks.

In How Ancient Concrete Heals Its Own Cracks, we explore the chemistry behind one of the most remarkable building materials of the ancient world.

Roman concrete was made differently from modern Portland cement concrete.

One important ingredient was lime.

When water reaches the lime clasts, chemical reactions can produce calcium-rich solutions.

Those materials can move through cracks and eventually form new mineral deposits that help seal them.

The process isn't biological healin ...