Aspects particuliers du comportement mecanique des tufs calcaires de Setif (Algerie) en assises de chaussees

In Algeria, the lack of high-quality aggregates in many regions represents the major challenge for the development of road infrastructures. The calcretes found in abundance are often the only alternative. Their use, adopted since the 1950s, is well mastered to date. However, their high sensitivity to water and their poor mechanical characteristics are increasingly limit their use in the face of traffic that has become heavy and dense. In this paper, the work carried out emphasizes the specific nature of these materials by evoking different aspects of their behaviour in base layers, which differs from traditional gravel layers. Thus, we discuss the problems related to the compaction operations, the origin of hardening and the often-negative influence of water on the mechanical characteristics of these materials. The study also made it possible to demonstrate the aptitude of the Setif calcretes for extrusion. This mechanical behaviour, hitherto unknown for this type of material, will deeply modify their structure and seriously affect their resistance to the effects of water and therefore reduce their mechanical performance. This phenomenon is probably responsible for the rapid emergence of severe damage due to significant permanent deformations on certain sections subjected to heavy and dense traffic during the winter period.