Building materials atural stone was the most important building material. Volcanic tuff stone was found in different colours. Travertine, white limestone from the surroundings of Tivoli, was also popular. Many Roman buildings were built of stone, without the use of mortar or cement, and later covered with bricks. Before stone, wood was the most important building material. The discovery of lime mortar brought about a big change. In the north volcanic sand was found, which yielded a hard building material if it was mixed with lime. Lime mortar had the advantage that it was comparatively cheap and strong. Wooden frames were filled with a mixture of rocks and lime mortar, the so-called 'opus caementicium'. Stones in all shapes - 'opus incertum' - were put on top. Later pyramid-shaped stones - 'opus reticulatum' - were used for this purpose. Quadrangular bricks were used as coverage. Important buildings were covered with marble plates.
|
