Lingyun Kong

High-internal-phase emulsified asphalt (HIPEA), characterized by a high asphalt volume fraction, may reduce water demand relative to conventional emulsified asphalt. However, the relationship between polyethylene glycol (PEG) molecular structure, asphalt–water interfacial organization, and laboratory stability remains incompletely quantified. This study compared four model systems containing octadecyltrimethylammonium chloride (STAC) alone or STAC combined with PEG with ethylene oxide (EO) numbers of 22, 45, and 55 (P22, P45, and P55). Molecular dynamics (MD) simulations were combined with dispersion observations, fluorescence microscopy, storage monitoring, centrifugation, differential scanning calorimetry (DSC), and exploratory Pearson correlation analysis. The results showed that STAC alone did not produce a uniform emulsion under the tested preparation conditions, whereas the PEG-containing formulations formed oil-in-water structures. The initial mean droplet diameter decreased from 4.20 μm for P22 to 2.57 μm for P55. After 22 days, the mean diameters were 6.70, 6.20, and 5.42 μm for P22, P45, and P55, respectively, indicating less pronounced droplet growth for the longer PEG formulations under the tested storage conditions. Under the same centrifugation protocol, the reported separated continuous-phase mass decreased from 0.233 g for P22 to 0.059 g for P55, corresponding to a 74.7% reduction based on these mass values. The characteristic DSC peak temperature increased from 49.853 °C for P22 to 61.105 °C for P55; this shift indicates a change in thermal response but does not, by itself, establish improved overall thermal stability. The MD results suggested differences in interfacial organization among the constructed systems. Pearson analysis identified exploratory associations between molecular descriptors and macroscopic indicators, but its interpretation is limited by the four-system dataset and the lack of strict compositional normalization. Overall, the findings provide molecular-level insights into the tested STAC/PEG systems and their laboratory stability. Further composition-controlled simulations and pavement-related testing are required before drawing conclusions about field performance.

1 According to statistics, early-built expressways, under the combined effects of heavy traffic and harsh environments, have an effective service life of only 60% to 70% of the designed service lif...

Interfacial coating loss in bitumen-coated aggregates is difficult to quantify because the exposed aggregate regions are spatially heterogeneous, visually subtle, and sensitive to illumination and background conditions. This study develops a fluorescence-based optical nondestructive evaluation (NDE) framework for quantitative assessment of bitumen–aggregate stripping under standardized laboratory imaging conditions. A dataset of 5760 fluorescence images was collected from 120 physical BAP specimens representing 20 bitumen–aggregate combinations, with six viewing directions recorded for each specimen under eight acquisition environments. A lightweight no-reference image quality assessment model (LAR-IQA), together with visual inspection of shadow suppression and segmentation robustness, was used to select a reference acquisition protocol. The black-background, UV plus natural-light, glass-enclosure configuration provided stable contrast while reducing shadow interference. Three candidate segmentation methods were benchmarked against manually annotated reference masks, and the HSVSC algorithm achieved the best overall performance, with the highest mean Dice coefficient of 0.73. Using the standardized sensing–processing workflow, the image-derived stripping ratio distinguished material-dependent coating-loss behavior and revealed significant sensitivity to acquisition parameters. Aggregate type dominated the measured response under the tested conditions, with the mean stripping level ranked as limestone (3.94%) < quartz fine sandstone (4.17%) < basalt (4.95%) < granite (15.56%). ANOVA based on the 20 combination-level mean stripping ratios derived from 120 specimens, together with grey relational analysis, further indicated that, within the tested material set, aggregate-related descriptors were more strongly associated with the measured stripping variation than the selected bitumen descriptors. The proposed framework provides a repeatable, non-contact optical NDE route for converting subjective visual stripping assessment into image-derived quantitative measurement.

1. Asphalt pavements are the predominant form of road engineering on a global scale, owing to their superior performance characteristics (Luo et al., 2022; Tarsi et al., 2020; Yaro et al., 2023). H...

1. Asphalt pavement, as the predominant form of modern transportation infrastructure, carries over 90% of global highway traffic (Bitumen, 2003; Yao et al., 2013). With the rapid expansion of highw...

The anti-slip performance of road surfaces directly affects traffic safety, yet existing evaluation methods based on texture features often suffer from limited interpretability and low accuracy. To overcome these limitations, a portable 3D laser surface analyzer was used to acquire road texture data, while a dynamic friction coefficient tester provided friction measurements. A multi-view fractal dimension index was developed to comprehensively describe the complexity of texture across spatial, cross-sectional, and depth dimensions. Combined with road surface temperature, this index was integrated into an XGBoost-based prediction model to evaluate friction at driving speeds of 10 km/h and 70 km/h. Comparative analysis with linear regression, decision tree, support vector machine, random forest, and backpropagation (BP) neural network models confirmed the superior predictive performance of the proposed approach. The model achieved backpropagation (R²) values of 0.80 and 0.82, with root mean square errors (RMSEs) of 0.05 and 0.04, respectively. Feature importance analysis indicated that fractal characteristics from multiple texture perspectives, together with temperature, significantly influence anti-slip performance. The results demonstrate the feasibility of using non-contact texture-based methods to replace traditional contact-based friction testing. Compared with traditional statistical indices and alternative machine learning algorithms, the proposed model achieved improvements in R² (up to 0.82) and reduced RMSE (as low as 0.04). This study provides a robust indicator system and predictive model to advance road surface safety assessment technologies.

UV radiation can change the internal molecular composition, macroscopic rheological properties, and microscopic chemical composition of asphalt. To study the effect of ultraviolet aging on asphalt and its structure–activity relationship, its rheological properties were measured by dynamic shear rheology and multiple stress recovery creep tests, its chemical compositions were measured by component composition, elemental composition, and infrared spectrum tests, and its molecular weight, distribution, and molecular structure were determined by gel permeation chromatography and nuclear magnetic resonance tests. Then, the molecular weight and molecular structure, rheological properties, and microchemical aging behavior of asphalt after UV aging were characterized by correlation analysis, and the structure–activity relationship was analyzed. The results show that the deformation resistance and elastic recovery ability of asphalt after UV aging are enhanced, and the flow performance is decreased. The ultraviolet radiation caused the aromatic hydrocarbons containing naphthenes and long alkyl chains in the asphalt to break and connect with asphaltenes with a ring structure. The asphaltene content in each bitumen sample exceeded 46%, and that in KL reached 55%, indicating that the bitumen changed into a gel structure. UV aging causes the aggregation of asphalt molecules, and the aggregation of molecules narrows the molecular distribution boundary and moves in the direction of macromolecules, resulting in the reduction of the dispersion coefficient by 2–10%. Hydrogen atoms will undergo condensation and substitution reactions due to long-chain breaking, cyclization, or aromatization under UV action, and the breaking of C=C bonds in carbon atoms will increase the stable aromatic ring, strengthen the stiffness of the molecular backbone, and make it difficult for the backbone to spin. Through correlation analysis, it was found that the molecular composition index could characterize the aging behavior index of asphalt, and that the aromatic structure was the most critical molecular change. Further, it was found that the sulfoxide group and carbonyl group could be used as evaluation criteria for the UV aging of asphalt because the correlation between them was above 0.7. This study provides an essential index reference for evaluating the performance change of asphalt under ultraviolet aging to save testing time. Moreover, the molecular structure characterization revealed the changes in internal molecular composition that were behind the observed aging properties, providing a theoretical basis for research on asphalt anti-aging technology.

The incorporation of waste fluid catalytic cracking (FCC) catalysts (WFCs) into asphalt pavements represents an effective strategy for resource utilization. However, the influences of the composition of the waste catalyst and its surface characteristics on the performance of asphalt mortars are still unclear. Herein, five WFCs were selected as powder filler to replace partial mineral powder (MP) to prepare five asphalt mortars. The diffusion behaviors of asphalt binder on the components of WFCs were investigated based upon molecular dynamic simulation, as was the interfacial energy between them. The adhesion work values between asphalt and WFCs were evaluated based upon the surface free energy theory. A dynamic shear rheology test and multiple stress creep recovery test on the WFC asphalt mortar were also conducted. Furthermore, the gray correlation analysis (GCA) method was employed to analyze the correlation between the diffusion coefficient and interfacial energy with the performance of WFC asphalt mortar. The results showed that the asphalt exhibited a low diffusion coefficient and high interfacial energy with the alkaline components of WFCs. The adhesion work values between asphalt and WFCs are higher than those with MP. The addition of WFCs can enhance the anti-rutting property of asphalt mortar significantly. Among the five WFCs, 2# exhibited the best improvement effect on the anti-permanent deformation ability of asphalt mortar, which may be due to its large specific surface area and moderate pore width. The GCA results suggest that the diffusion coefficient and interfacial energy strongly correlated with the performance of asphalt mortar, with an order of adhesion > permanent deformation resistance > rutting resistance. This study provides both theoretical and experimental support for the application of WFCs in asphalt materials.