Evaluation of rheological behavior of asphalt mixtures modified with triblock polymers grafted maleic anhydride and montmorillonite clay

Abstract

AbstractThis work presents an investigation of the incorporation of maleic anhydride (MAH)‐grafted triblock copolymers and montmorillonite clay (Mt) as modifiers of asphalt. A series of unmodified copolymers styrene‐butadiene‐styrene (SBS), styrene‐isoprene‐styrene (SIS), or styrene‐ethylene/butylene‐styrene (SEBS) with clay were prepared by direct mixing of all components. Subsequently, they were compared with their grafted‐MAH copolymer counterparts. The asphalt blends were characterized with respect to their rheological, morphological, and physical properties. Experimental results revealed that SBS and SIS grafted‐copolymer composites increase the softening point by 1.5%–7%, while the penetration decreases by 2%–15% in comparison to the homologous nongrafted polymers. The improvement can be directly linked to the continuous network polymer in the asphalt blends. The combined use of styrene‐isoprene‐styrene‐g‐MAH (SIS‐g‐MAH) copolymer and clay impart higher elastic behavior than that of the other blends. G′ increases about 95% in comparison to that of SIS/Mt, while the complex viscosity is three decades larger in the low frequencies region. Elevated rutting resistance temperature (>100°C), tanδ <5, reveals a solid‐like behavior with no Newtonian plateau. SEBS‐g‐MAH/Mt presents diminished rheological properties with respect to those of SEBS/Mt due to poor dispersion and agglomeration of clay particles in the polymer and asphalt matrix.