Study of aggregate-mastic bond properties in bituminous mixtures

Abstract

The durability of bituminous mixtures in the pavement depends on their characteristics (particularly, the voids content) and on weather conditions. In fact, the premature distress of pavements usually occurs in poorly compacted mixtures, especially in the presence of water. The intrusion of water in the bituminous mixtures strips the mastic binder from the aggregates, thus leading to the rupture of the aggregate-mastic bonds, which in the most severe cases is manifested by the disaggregation of the mixture in the surface layer of the pavement. Consequently, the main objective of this work is the study of the aggregate-mastic bond strength of different mixtures and the evaluation of the influence of water and aging on that bond strength. The bond between the mastic and the aggregates is evaluated by using two monotonic tests (tensile and shear). The influence of water and aging is evaluated by comparing the strength of conditioned and unconditioned samples. The main conclusions of this work result from the analysis of the aggregate-mastic bond strength under different test conditions. The influence of the mixtures composition, water and aging conditioning on the bonding properties is observed, as well as the main causes of the aggregate-mastic stripping in dense mixtures, usually applied in situ.