Eifel Aqueduct - Architectural Aspects

Architectural Aspects

To protect against frost, most of the aqueduct ran about 1 m below the Earth's surface. Archaeological excavations show that, at the lowest level, the Roman engineers had placed a loose layer of stones. On this base, they set a concrete or stone U-shaped groove for the water and, over this, cut stones and mortar were used to build a protective arch.

For the concrete work and the arch, the engineers used boards to build the form. Impressions of the wood grain remain in the concrete 2,000 years later. The aqueduct had an inner width of 70 centimetres (28 in) and a height of 1 metre (3.3 ft), so a worker could enter the tube when necessary. The outside of the aqueduct was plastered to keep dirty water out. At several locations, a drainage system was set up alongside the aqueduct to keep ground water away. Smaller streams crossed the aqueduct through culverts: one, very near the source, is still well-preserved.

The inside of the aqueduct was also plastered with a reddish mixture called opus signinum. This mixture contained lime as well as crushed bricks. This material hardened under water and prevented leakages to the outside. Small cracks were sealed with wood ash, which was strewn over them the first time the aqueduct was set in operation.