Les mortiers hydrauliques : synthèse bibliographique et premiers résultats sur des mortiers de Gaule romaine

Abstract

This article is a bearing «state of the art» on the mortars containing hydraulic lime and the air lime-based mortars with reactive aggregates : natural and artificial pozzolanas. The analyses of these last years on the Gallo-Roman lime mortars show a systematic use of air lime, which supposes a selection of the purest limestone in the geological environment. The field of the Gallo-Roman hydraulic mortars consist mainly in lime mortars with brick dust, natural pozzolanas being not very abundant in Gaule. In the terra cotta, the heat treatment of clays involves the formation of reactive glass, as well as that of pozzolanas. It is considered that only the mortars with fine brick dust make possible to obtain mortars rich in pozzolanic compounds. But the mechanical resistance of many concretes with large fragments of brick and tile proves, following the example junctions between sandy mortars and bricks of a masonry, that the contact reactions between lime and the terra cotta reinforce considerably the mechanical properties of the material. The multispectral image processing allows the study of these edge phenomena.