چكيده به لاتين
The overall objectives of this study is to evaluate the application of Coarse Recycled Concrete Aggregate (CRCA) as an alternative for coarse natural aggregate and to evaluate the use of black liquor as an alternative for part of pure bitumen in asphalt mixtures within Iran specifications and to assess also the physical properties of recycled concrete aggregate treated with hydrated lime slurry compared to untreated CRCA and also to study SMA asphalt mixture containing treated CRCA. For this purpose asphalt mixtures with 0% (control), treated and untreated 50% and 100% of CRCA and also 0% and 20% black liquor were produced. Marshal staility, draindown, resistance of SMA mixture to moisture-induced damage, indirect tension stress (ITS), resilient modulus (MR), dynamic creep and indirect tensile fatigue (ITF) were analysed. The results indicate that as the percentage of CRCA in SMA asphalt mixtuer, the stiffness of SMA asphalt mixture (ITS, resilient modulus, dynamic creep and ITF) decreased. The two advantages of SMA mixture were containing CRCA, increasing Marshall stability and moisture sensitivity to the control mixture. Compared to Natural Aggregate (NA), the obtained results indicated that CRCA has inferior physical and mechanical properties. CRCA has a lower Bulk Relative Density (BRD), higher water absorption, and higher porosity than NA. With respect to the mechanical properties, CRCA has a higher abrasion loss than NA. The amount of adhered mortar and the original source of CRCA have a considerable effect on these properties. The pre-soaking method involved the use of hydrated lime slurry which results in lower absorption with an approximate decrease of 32% and decreased abrassion loss with an with an approximate reduction of 2%. The results of the experiments also show that black liqueur, in addition to replacing part of the bitumen, also improves the performance of the asphalt mixture. But the use of 20% black liquor which results in lower resistance of mixture to moisture-induced damage with an approximate decrease of 14%. The results of SMA asphalt mixture with 100% modified CRCA and 20% black liquor had acceptable and almost close results to the control mixture in the modulus of robustness, dynamic creep and diagonal fatigue tests.
