engleski

Rheological evaluation of bitumen modified with styrene butadiene styrene block copolymer

Polymers are the most common modifier currently being used to improve bitumen, BIT, rheological properties. The use of bitumen as an asphalt binder is known for many years. There are a number of properties that BIT must satisfy as a binder and these are: good rheological properties, resistant to deformation at the oscillating frequency of the load due to traffic and temperature resistance. The use of polymer modifiers contributes to the improvement of its properties. In this paper styrene-butadiene-styrene block copolymer, SBS is used as modifier. Two types of SBS polymers are used: linear SBS, SBS-L and radial, SBS-R. The polymers modified bitumen ; PmBs are prepared with various content of SBS-L and SBS-R polymers. The aim of this research is to put the emphasis on testing of rheological properties, because the standard methods of testing bitumen are empirical methods that cannot clearly define the bitumen characterization of different temperature sensitivity. Rheological properties complex modulus, G*, complex viscosity, ni* and phase angle, delta are followed with dynamic shear rheometer, DSR in linear viscoelastic range, LVE in broad temperature range at traffic frequency. The critical temperatures are determined at which PmBs satisfiers the conditions without permanent deformation, accorsing to SHRP program. Conventional tests (penetration, ring and ball temperature, ductility, elastic recovery, Frass breaking point) were also determined. All investigations are done before and after ageing in the condition of thermooxidative degradation. Results of the investigation indicate the great influence of both polymers and ity contents on the rheological properties of polymer modified bitumen. SBS block copolymers increse the elasticity of the bitumen at high temperatures and contributing to a better flexibility at low temperatures. PmBs have higher critical temperature what means the higher resistance to permanent deformation. The determined rheological properties are in agreement with the results of conventional tests. After ageing the hardening of BIT and PmBs occurs.

Bitumen; Polymer modified bitumen; Rheological properties; Dynamic shear rheometer (DSR); SBS-L; SBS-R; Thermooxidative degradation; Styrene Butadiene Styrene (SBS); Stability

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