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Abstract
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Owing to climate conditions, heavy traffic loads, and increasing axial loads, conventional
bitumen/asphalt should be modified. Bituminous materials are also vulnerable to aging during
construction and service time of pavement, which will seriously affect the service
performance/life of bitumen pavement. To this end, bitumen was modified using styrenebutadiene-
styrene (SBS), ZnO, TiO2 and ethylene vinylacelate (EVA). Applied methodology
was Mixture Design and contents of SBS, ZnO, TiO2 and EVA were considered as
independent variables. Response variables followed as: G*/sin OB, G*/sin RTFO, G*/sin
PAV, RV, penetration (PEN), softening, ductility, m-value and stiffness. Results of
experiments of penetration degree, softening point, and ductility performed on basic bitumen
without any additives were 89, 49 °C, and 137, respectively. Effects of independent variables
were investigated on response variables using mathematic models and optimized
compositions. SBS, ZnO, TiO2 and EVA precursors positively affected the PEN parameter.
Manipulated samples possessed penetration range of 48–62 (1/10mm). Maximum softening
was reached at the highest EVA and the minimum softening was detected at the largest ZnO
and TiO2. Softening point ranged in 59–71 °C. SBS, ZnO, TiO2 and EVA components
positively increased ductility and the largest positive effect belonged to SBS. SBS and EVA
positively affected G*/sin OB response, whereas ZnO and TiO2 variables negatively
decreased it. Dynamic shear rheometric (DSR) data for aged bitumens within short term
periods decreased from 52 to 76 °C for all investigated samples. All mentioned modifications
were performed to optimize performance of ultimate bitumen from perspectives of softening,
ductility, strength, m-value, stiffness, etc.
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