engleski

Rheological properties of styrene butadiene styrene modified road bitumen

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, 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 can not clearly define the consistency of bitumen and rheological behavior in a wide temperature range, especially when bitumen characterization of different temperature sensitivity. Rheological properties complex modulus, G*, complex viscosity, * and phase angle,  are followed with dynamic shear rheometer, DSR in linear viscoelastic range, LVN in broad temperature range at traffic frequency. The critical temperatures are determined at which PmBs satisfies the conditions without permanent deformation, according to SHRP Program. Conventional tests (penetration, ring and ball temperature, ductility, elastic recovery, Frass breaking point) where also determined. Results of the investigations indicate the great influence of both polymers and its contents on the rheological properties of polymer modified bitumen. SBS block copolymers increase the elasticity of the bitumen at hight 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.

polymer modified bitumen; rheological properties; DSR; SBS-L; SBS-R

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