Ancient Roman concrete outperforms our own, and science only just worked out why

The Roman Empire may be long gone, but its architecture has stood the test of time — most notably, its insanely durable concrete, which has been hailed as the world’s strongest. The building material, which still remains intact and stronger than ever in many places, has long puzzled scientists who couldn’t fully explain why it was so remarkably strong, or why modern efforts to duplicate its strength have fallen flat. Now, new research suggests that the ancient concrete’s