Durability assessment of asphalt mixtures by anti stripping additives

This report summarizes research involving the comparison of new additive materials for binder to reduce water damage of asphalt concrete. The study was a cooperative effort between the Engineering and civil organization of Tehran municipality and Paral Kish and Tarahan Ghir Novin companies. Fabricated asphalt specimens, which were made by two kinds of anti stripping materials, one type of asphalt cement and three types of aggregate, were examined according to SHRP test method and evaluated by constructing asphalt mixtures in the laboratory. Moisture damage is a complex phenomenon that involves thermodynamic, chemical, physical and mechanical processes. The interaction between bitumen and aggregate is a primary determinant of asphalt mixture strength; not only is adhesion between bitumen and aggregate related to the aggregate, but it is also a bitumen property. To achieve this objective, 6 different HMA combinations using different mix parameters and different anti stripping agents (with acidic and basic basis) were evaluated for their resistance to moisture conditioning and using the modified Texas Boiling test. A laboratory investigation of stripping of asphalt mixtures has been performed using the Marshall - Immersion test. Marshall specimens were prepared at optimum asphalt contents were exposed to freezing–thawing conditioning according to AASHTO T283. The results indicate that aggregate type has a dominant influence on the bitumen aggregate bond. Nevertheless results revealed that anti stripping additives has improved stability and stiffness of bituminous mixtures, because the adhesive forces between asphalt and aggregate and the mechanical interlock between aggregate particles have been improved due to treatment.

Durability assessment of asphalt mixtures by anti stripping additives Keywords:

Modifier , Lottman procedure , Immersion-Compression , percent retained strength , antistripping additives or agents ,