Investigation of effects of mixing temperature on the resistance to moisture-induced damage and fatigue life of hot mix asphalts

Investigation of Effects of Mixing Temperature on the Resistance to Moisture-Induced Damage and Fatigue Life of Hot Mix Asphalts Highway flexible pavements consist of subbase, base and pavement layers. Bituminous materials are used in the pavement and base layers as binder. Pavement layers can be constructed in various ways, but hot mix asphalts offer utmost durability. Hot mix asphalt pavements are attained through blending bitumen and aggregate at a certain high temperature in a stable plant, transporting the material to the application area and compacting the mixture at a proper temperature and compaction ratio. For the hot mix asphalt to perform well, it is essential to have proper materials, adequate design, efficient manufacture and application. Owing to technical reasons and labour defects, adequate temperature of bitumen and aggregate mixture may not be attained. In this study, mixture samples have been prepared at mixing temperature and 10°C, 15°C ve 20°C lower than the mixing temperature. Samples have been prepared with 5% styrene-butadiene-styrene (SBS) and 18% American Gilsonite (G) modified binders as well as pure binder. Marshall stability and flow, resistance to moisture-induced damage, indirect tensile stiffness modulus and indirect tensile fatigue tests were applied on the mixture samples. As a result of the tests, it was determined that Marshall stability, indirect tensile strength, resistance to moisture-induced damage, stiffness and fatigue lives of mixtures increased with additive usage. Meanwhile, as mixing temperature decreased, so did these levels. Key Words: Bituminous hot mixture, mixing temperature, styrene-butadiene-styrene, American Gilsonite, stiffness.