Diagram of layers of the Roman via: 1. leveled earth, 2. statumen, or stones, 3. audits, or rubble, 4. nucleus, or bedding of fine cement made of potshards and lime, 5. dorsum or agger viae, the crown of the road made with polygonal blocks, 6. raised sidewalk, 7. edge stones. Image: Wikimedia. [Click to enlarge
Concrete