Determination Of Compaction Temperatures For Warm Mix Asphalt Based On Air Voids

The use of WMA additives allow significant lowering of the production and paving temperature of Asphalt Mix by reducing the viscosity of asphalt binder and/or increasing the workability of mixture.Despite the promising benefits of WMA in comparison with HMA, due to the relative newness of these technologies, various concerns have not as yet been resolved. It is apparent that current mixture design procedures were developed for conventional asphalts, not for WMA. Durability concerns, WMA design procedures especially the determination of mixing and compacting temperatures should be taken into account to ensure equal or better performance of WMA than Hot Mix. In this research, a detailed literature review and laboratory tests including density tests, dynamic stability, and bending beam test were performed on WMA mixtures with two WMA additives to investigate the effectiveness of using air voids method to determinate the compaction temperature for WMA. This study evaluated the mechanical evaluated the effectiveness of determination of compaction temperature for WMA mixes based on air voids of Marshal hummer compacted mixtures, Binder-based tests such as penetration, softening point, ductility, viscosity, short-term and long-term tests were conducted, other measured properties include the complex shear modulus (G*), the phase angle (8), Stiffness of binders.Analysis of rheological properties test results showed that the Performance Grade (PG) of base asphalt is PG58-22.For mixture-based tests it was observed that the addition of WMA additives improved the compact ability of mixtures; air voids were significantly decreased when temperature increased and 125? temperature showed better air voids percentage.With air void method to determine WMA mixtures compaction temperature, the point at which mix will consolidate(compact) or flow can be determined.This method makes it possible to achieve the desired density for the compacted asphalt mix which is known to be related to the pavement performance,appropriate percentage of air voids can be design value for determining WMA compaction temperature. With compaction temperature determined by this method, analysis of mechanical properties of WMA showed that reduction of the compaction temperature for mixture with additive A is possible while maintaining low temperature performance and without having an increased susceptibility to permanent deformations.