Influence of lateral confining pressure on flow number tests

The study described in this paper aimed to investigate the rutting resistance of bituminous mixtures by means of flow number tests, with a particular emphasis placed on the analysis of the effects produced by var-iations of lateral confinement. Two wearing course mixtures, one standard dense-graded and one rubberized gap-graded, were employed in the experimental investigation in order to highlight the influence of confining pressure on materials with significantly different bulk structure and rheological properties of the binder phase. Flow number tests were carried out at a single test temperature and in three confinement conditions on cylindrical samples compacted at two air void contents. Obtained results suggest that confining pressure can significantly affect flow number values to an extent that depends on mixture type and composition, indi-cating the importance of selecting proper testing conditions in order to achieve a reliable performance-based ranking of materials.