Researchers have unlocked the chemistry of Roman concrete which has resisted the elements for thousands of years.
Ancient sea walls built by the Romans used a concrete made from lime and volcanic ash to bind with rocks.
Now scientists have discovered that elements within the volcanic material reacted with sea water to strengthen the construction.
They believe the discovery could lead to more environmentally friendly building materials.
Unlike the modern concrete mixture which erodes over time, the Roman substance has long puzzled researchers.
Rather than eroding, particularly in the presence of sea water, the material seems to gain strength from the exposure. Read more.

