Study of the Influence of SBS and APDDR on the Low-Temperature Properties of Road Bitumen

A comparative assessment of the effect of two modifiers on the low-temperature properties of BND 90/130 bitumen was investigated using Asphalt Binder Cracking Device (ABCD test) and Dynamic Shear Rheometer (DSR 4-mm test). These modifiers are styrene-butadiene-styrene block copolymer (SBS) and active powder of discretely devulcanized rubber (APDDR) - powder elastomeric modifier obtained by high-temperature shear grinding of waste tire crumb rubber. ABCD results of RTFO-aged samples showed clear and gradual decrease of the ABCD cracking temperature (improvement) for all BC as the modifier concentration increases. It is noteworthy that the Bitumen Composites (modified bitumens) were cracking at higher strain and fracture stress values compared to neat bitumen. Results of DSR-4 mm test showed a decrease in the complex shear modulus (G*), storage modulus (G¢) and loss modulus (G²) BC compared to the neat bitumen. It is shown that bituminous composites have no maximum on the Cole-Cole diagram (dynamic vitrification) at T = -28°C which is observed in the neat bitumen.