Composite materials in ancient structures

Mortars and concretes employed in ancient structures concern composite materials which have exhibited excellent durability through time. They were used as lining materials in cisterns, wells, aqueducts, shafts and duct drains, as supporting materials for pavements and mosaics, as plasters on external and internal walls, as supporting materials for frescoes and as joint mortars on masonry structures. They were comprised of various binding materials (or mix of them) and natural or artificial aggregates, along with natural or artificial pozzolanic additions, primarily of volcanic origin, that improved their performance and prolonged their longevity. Moreover, various types of organic substances were employed to increase plasticity and regulate setting rates, while fibrous materials were commonly used to obtain greater strengths or to avoid cracks due to the shrinkage during setting. The comprehension of the production procedures employed and of the physico-chemical and mechanical characteristics of such composite materials can be achieved by integrating properly the results of various analyses. Data obtained from tests performed on a large number of historic composites sampled from ancient structures in the Mediterranean Basin permitted the identification of physico-chemical and mechanical characteristics of the most typical mortars encountered in ancient structures.