Asphalt fumes released at high temperatures significantly impact human health and the natural environment. This study systematically investigated the microstructure and compositional characteristics of tea stalk biochar (TB) from pyrolysis at different temperatures (300℃, 400℃, 500℃, and 600℃) and its adsorption capacity for asphalt fumes. Scanning electron microscopy and Brunauer-Emmett-Teller analysis indicated that increasing pyrolysis temperatures enhanced the porosity and BET surface area of TB, transitioning its structure from dense and low-porosity to highly porous. Fourier-transform infrared spectroscopy and elemental analysis revealed that higher temperatures promoted biochar graphitization, reduced oxygen-containing functional groups, and increased hydrophobicity and aromaticity. Analysis of asphalt fumes demonstrated that adding 1 % TB significantly reduced asphalt fume emissions, including VOCs, H₂S, SO₂, and NOₓ. TB prepared at 500℃ (500TB) exhibited optimal adsorption, reducing VOCs by 68.6 % and H₂S by 87.5 %. GC-MS analysis further revealed that 1 % 500TB reduced aliphatic hydrocarbons, aromatic compounds, oxygen-containing compounds, and sulfur-containing compounds in asphalt VOCs by 63 %, 69 %, 67.2 %, and 63.3 %, respectively. The superior adsorption performance of 500TB was attributed to its larger surface area, diverse mesoporous structure, and high aromatic carbon content, enhancing its affinity for pollutants. Physical tests indicated that biochar enhances the thermal stability and deformation resistance of asphalt by increasing its softening point, viscosity, and penetration index, while maintaining acceptable ductility. These findings demonstrate the effectiveness of TB for mitigating asphalt fume emissions.

Despite biochar has a good ability in suppressing asphalt fumes, the relationship between the structure of biochar derived from different plant sources and its performance in adsorbing fumes has not yet been explored. In this study, biochar with varying structures and compositions was prepared from cellulose-rich (tea stalks and poplar sawdust) and lignin-rich (coconut shell fiber and loofah sponge) biomass and used as asphalt fume suppressants. Structural characterization revealed that all biochar developed abundant pore structures. Specifically, cellulose-rich biochar featured macro-/mesoporous structures with relatively oxygen-rich surfaces, while lignin-rich biochar exhibited micro-/mesoporous structures with enhanced π-conjugated graphitic frameworks. Asphalt fume adsorption tests showed that, cellulose-based biochar was more effective in adsorbing H₂S and NOₓ, whereas lignin-rich biochar exhibited superior adsorption of VOCs. GC-MS analysis confirmed that cellulose-rich biochar facilitates the adsorption of polar pollutants due to its higher oxygen-rich surfaces, while lignin-rich biochar enhances the adsorption of aromatic pollutants through π–π interactions. Physical property tests of asphalt showed that the macropores of cellulose-rich biochar absorbed more light fractions and promoted an increase in asphaltenes content, significantly enhancing high-temperature performance but having an adverse effect on asphalt ductility.

This research aims to investigate the aging resistance of asphalts from different crude oils based on molecular structure and rheological properties. The average molecular structure of five types of asphalt from different crude oils were analyzed with the element analyzer, nuclear magnetic resonance, gel permeation chromatograph, and the improved Brown–Ladner method. The rheological properties of the asphalts were tested by the dynamic shear rheometer before and after laboratory aging. The antiaging properties of the asphalts were evaluated by the rheological aging index (RAI). The findings indicate that there were significant differences in the molecular structures among the five types of asphalt. The asphalt with the least hydrogen–carbon ratio (H/C), the largest aromatic carbon ratio (f_A), and the largest condensation index (CI) had the lowest rate of decline in rheological properties and therefore, the best antiaging performance. The H/C, f_A, and CI had good correlations with RAI, which indicated that it was feasible to use these molecular structure parameters to evaluate the differences in the aging resistance of various asphalts.