Experimental investigation on the preparation and surface treatment of biomass fibers for stone mastic asphalt mixtures modification.

• The preparation and surface treatment methods for producing bamboo and corn straw biomass fibers were proposed. • The enhancement effects of proposed biomass fibers on the road performance of SMA mixtures were validated. • The micromorphology evaluation demonstrated the mechanism of biomass fiber reinforcement in SMA mixtures. With the sustainable development of infrastructure construction materials, the use of renewable biomass resources in asphalt mixtures could contribute to better sustainability. The bamboo fibers and corn straw fibers with lengths ranging from 1.5 to 12 mm were produced in the laboratory through the proposed crushing, steaming, and grinding processes. A surface treatment with the phenolic resin copolymer modifier was utilized to reconstruct the micro-surface of biomass fibers. The surface treatment effectively reduced the oil absorption multiplier and mass loss of proposed biomass fibers by about 0.6 and 2 %, respectively. The FI-IR absorption peak and change of micromorphology also validated the effective surface reconstructive. Afterward, the virgin asphalt (70#) mixtures and SBS-modified asphalt mixtures with/without biomass fibers were produced for road performance tests and fatigue resistance tests. The results showed that the proposed biomass fibers contributed to about 20 % to 30 % improvement in the high-temperature performance, while the low-temperature cracking resistance was also obviously increased. In addition, the moisture damage resistance and fatigue life were also improved after the addition of biomass fiber modifier, in which the residual stability and tensile strength ratio were increased by about 9 % and 6 % by comparing that with fibreless mixtures, respectively. By comparing the effect of different types and lengths of fiber modifiers, the long bamboo fiber with surface treatment represented the optimized strengthening efficiency. The enhancement mechanism of proposed biomass fiber modifiers was revealed through the microstructure observation. The feasibility of using proposed biomass fibers with surface treatment for producing high-performance SMA has been verified, which can be utilized in the field application for replacing the lignin fiber modifiers for achieving better sustainability. [ABSTRACT FROM AUTHOR]