Laboratory Evaluation of Asphalt Mixtures that Contain Biobinder Technologies

Abstract

The use of biobinder as a replacement for petroleum-based asphalt binders has received considerable attention in recent years. The objective of the study reported in this paper was to conduct a comprehensive laboratory evaluation of asphalt mixtures that contained biobinder technology at a content of 20%, 25.5%, 30%, and 50%. To achieve this objective, Superpave® performance grade (PG) of the modified blends was compared with the unmodified binder. In addition, laboratory tests were conducted to capture the mechanistic behavior of the mixtures against major distresses. Laboratory testing evaluated the rutting performance, moisture resistance, and fracture resistance of the produced mixtures with the use of the Hamburg loaded-wheel tester, the modified Lottman test, the semicircular bending test, and the thermal stress restrained specimen test. Results of the experimental program showed that the use of biobinder did not influence the final PG of the binder with the exception of one blend, which dropped one grade at low temperature. Mixtures modified with biobinder had rutting performances that were similar to, or improved, compared with those of the conventional mixes. With respect to moisture susceptibility, all mixtures, except the mixes prepared with PG 67-22, exceeded the 80% tensile strength ratio. However, when an antistripping agent was added, the tensile strength ratio of the mix with 50% biobinder exceeded 80%. At intermediate temperatures, the mixes that contained biobinder exhibited less fracture resistance than the conventional mixes did. Biobinder modification improved the low-temperature fracture performance of the mixtures compared with that of the conventional mixtures of similar PG.