Laboratory Investigations of Mechanical Performance of Foamed Bitumen Mixes that Use Half-Warm Aggregates

For several years, as environmental criteria have become stricter and stricter, new moderated-temperature mixing technologies–warm or even half-warm (less than 100°C)–have appeared. This study, realized in Laboratoire Central des Ponts et Chaussées (LCPC) in Nantes, France, within the framework of the partnership between Eiffage Travaux Publics and LCPC, aimed at determining the influence of mixing parameters (such as temperature and initial water content of the mix aggregates) on the quality of mixing and the mechanical properties of the half-warm foamed bitumen mixes compared with the traditional cold-foamed bitumen mix and hot-mix asphalt, both of which acted as reference materials. It was also a way to understand better the role of water and its influence on asphalt quality. This study highlights the influence of the increase in the aggregate temperature to elaborate mix treated with foam bitumen. This coating process allows many benefits: an increase in coating quality, compactibility, and water resistance. As a consequence, mechanical performances are improved.