Evaluation of Different Additives on Mechanical Properties and Performance of Hot Mix Asphalt Using Marshall Stability and ITSM Tests

Abstract

This study comprehensively evaluated the mechanical performance of hot mix asphalt (HMA)mixtures prepared with neat and modified binders using Marshall stability and Indirect Tensile StiffnessModulus (ITSM) tests. Marshall stability test results revealed that the incorporation of polymeric and reactiveadditives increased the stability values of the mixtures compared to those produced with neat binder. Among the additives investigated, the 611 elastomer demonstrated the highest improvement in stability, achieving up to1.80 times higher values than the neat mixture. Other additives, such as 701, SBS, and CR, also enhanced stability, albeit to varying extents. The ITSM test results indicated that the stiffness modulus of the mixtures increased with higher elastomer content. The 611 elastomer exhibited the most significant impact on stiffness among the tested elastomers, while 701 and SBS showed comparable performance. Furthermore, higher ITSM test temperatures resulted in decreased stiffness values across all mixtures. The number of load repetitionsrequired to initiate cracking was found to be lowest in the mixtures containing neat binder and highest in mixtures containing 4% of the 611 elastomer, indicating superior fatigue resistance. Overall, both Marshall and ITSM tests confirmed that modified binders, particularly those incorporating the 611 elastomer, significantly enhance the mechanical properties of HMA mixtures, improving their resistance to deformation and crackingunder load.