Pavement surface texture features are one of key factors affecting the skid resistance of pavement. In this study, a set of stable and reliable texture measurement equipment was firstly assembled by using the linear laser ranging sensor, control system and data acquisition system. Secondly, the equipment was calibrated, and the superposition error of sensor and control system was tested by making a standard gauge block. Thirdly, four different kinds of asphalt mixture were designed, and their surface texture features were obtained by leveraging a three-dimensional laser scanner. Therefore, the surface texture features were characterized as one-dimensional profile features and three-dimensional surface features. At the end of this study, a multi-scale texture feature characterization method was proposed. Results demonstrate that the measurement accuracy of the laser scanning system in the x-axis direction can be controlled ranging from −0.01 mm to 0.01 mm, the resolution in the XY plane is 0.05 mm, and the reconstructed surface model of surface texture features can achieve a good visualization effect. They also show that the root mean square deviation of surface profiles of different asphalt pavements fluctuates greatly, which is mainly affected by the nominal particle size of asphalt mixture and the proportion of coarse aggregate, and the non-uniformity of pavement texture distribution makes it difficult to characterize the roughness of asphalt pavement effectively by a single pavement surface profile. This study proposed a texture section method to describe the 3D distribution of road surface texture at different depths. The macrotexture of the road surface gradually changes from sparse to dense starting from the shallow layer. The actual asphalt pavement texture can be characterized by a simplified combination model of “cone + sphere + column”. By calculating the surface area distribution of macro and microtextures of different asphalt pavements, it was concluded that the surface area of asphalt pavement under micro scale is about 1.8–2.2 times of the cutting area, and the surface area of macrotexture is about 1.4 times of the cutting area. Moreover, this study proposed texture distribution density to characterize the roughness of asphalt pavement texture at different scales. The S_MA index can represent the macroscopic structure level of different asphalt pavements to a certain extent, and the S_MI index can well represent the friction level of different asphalt pavements.

Three-dimensional (3D) ground-penetrating radar is an effective method for detecting internal crack damage in pavement structures. Inefficient manual interpretation of radar images and high personnel requirements have substantially restrained the generalization of 3D ground-penetrating radar. An improved Crack Unet model based on the Unet semantic segmentation model is proposed herein for 3D ground-penetrating radar crack image processing. The experiment showed that the MPA, MioU, and accuracy of the model were improved, and it displayed better capacity in the radar image crack segmentation task than current mainstream algorithms do, such as deepLabv3, PSPNet, and Unet. In the test dataset without cracks, Crack Unet is on the same level as deepLabv3 and PSPNet, which can meet engineering requirements and display a significant improvement compared with Unet. According to the ablation experiment, the MPA and MioU of Unet configured with PMDA, MC-FS, and RS modules were larger than those of Unet configured with one or two modules. The PMDA module adopted by the Crack Unet model showed a higher MPA and MioU than the SE module and the CBAM module did, respectively. The results show that the Crack Unet model has a better segmentation ability than the current mainstream algorithms do in the task of the crack segmentation of radar images, and the performance of crack segmentation is significantly improved compared with the Unet model. The Crack Unet model has excellent engineering application value in the task of the crack segmentation of radar images.

The bonding performance of epoxy resin adhesives plays a critical role in ensuring interlayer adhesion and long-term durability in steel bridge deck pavements. However, the construction environment temperature and curing time significantly influence the bonding properties of epoxy resin adhesives. To address this issue, systematic evaluations of the bonding performance and tack-free time of epoxy resin adhesives were conducted. The results demonstrate that under identical curing durations, the tensile bond strength between the epoxy resin bonding layer and steel plate increases with higher curing temperatures. Similarly, at constant curing temperatures, extended curing times lead to improved tensile strength. Both higher temperatures and longer curing durations reduce the tack-free time of the epoxy resin adhesive. Under natural outdoor curing conditions, the epoxy resin adhesive achieves design requirements for both tensile strength and tack-free time after 48 h of curing, ensuring optimal interlayer bonding and workability. Conversely, prolonged curing beyond 72 h results in significantly reduced bonding strength while maintaining acceptable tack-free time. For ambient temperature conditions, the optimal curing duration for epoxy resin adhesive is determined to be 48~72 h, balancing both bonding performance and construction requirements (preventing adhesion to construction equipment). This research offers technical guidance for the field construction of epoxy pavement on steel bridge decks by establishing optimal curing protocols for epoxy resin adhesives to ensure reliable bonding performance and construction workability.

The size, shape, gradation and appearance of aggregate have a significant impact on the road performance of asphalt mixtures, which is directly related to the deformation characteristics and fatigue resistance of asphalt mixtures. In order to be able to design a long-life asphalt pavement, the aggregate must have reasonable morphology and morphological characteristics. In order to quantitatively analyze the shape characteristics of the road coarse aggregate, a high-precision three-dimensional scanner is used to obtain the characteristic lattice of the aggregate surface, and the solid model of the coarse aggregate particles is established. The two-dimensional and three-dimensional morphological indicators of the aggregate are analyzed and discussed. Meanwhile, aggregates processed by typical quarries in Guangdong Province are collected, and the influence of different processing techniques on the morphology of aggregates are analyzed. The results show that the difference between the perimeter and projected area of the aggregate contour under different viewing angles is relatively large, which is closely related to the flatness index of the aggregate. It can better characterize the three-dimensional shape of the aggregate. The closer the aggregate is to the cubic state, the greater the sphericity value; the ellipsoid index calculated based on the three-dimensional circumscribed ellipsoid can better characterize the angularity of the aggregate. The worse the angularity of the aggregate, the larger the corresponding ellipsoid value. The sphericity of the aggregate processed by counter-breaking is lower, and the angularity is better. The sphericity of the aggregate processed by the shaping process is the best, but the angularity is lower. According to actual needs, different processing techniques can be combined and blended to obtain aggregate finished products with a more balanced grain shape and angularity. The richer the angularity of the coarse aggregate, the better the high-temperature stability and fatigue resistance of the asphalt mixture. However, the stability of performance indicators will become worse. In practical engineering applications, it is recommended to further combine the screening efficiency of the hot material screen of the mixing plant with the stability of the hot material gradation and the uniformity of construction quality to select a suitable aggregate processing technology.

Coarse aggregate is the main component of asphalt mixtures, and differences in its morphology directly impact road performance. The utilization of standard aggregates can benefit the standard design and performance improvement. In this study, 3D printing technology was adopted to prepare artificial aggregates with specific shapes for the purpose of making the properties of artificial aggregates to be similar to the properties of natural aggregates. Through a series of material experiments, the optimal cement-based material ratio for the preparation of high-strength artificial aggregates and corresponding manufacturing procedures have been determined. The performance of the artificial aggregates has been verified by comparing the physical and mechanical properties with those of natural aggregates. Results indicate that using 3D printing technology to generate the standard coarse aggregate is feasible, but its high cost in implementation cannot be ignored. The 3D shape of the artificial aggregate prepared by the grouting molding process has a good consistency with the natural aggregate, and the relative deviation of the overall macro-scale volume index of the artificial aggregate is within 4%. The average Los Angeles abrasion loss of artificial cement-based aggregate is 15.2%, which is higher than that of diabase aggregate, but significantly lower than that of granite aggregate and limestone aggregate. In a nutshell, 3D printed aggregates prepared using the optimized cement-based material ratio and corresponding manufacturing procedures have superior physical and mechanical performance, which provides technical support for the test standardization and engineering application of asphalt pavements.

To address the challenge of assessing the thickness uniformity of epoxy asphalt layers on steel bridge decks, three-dimensional ground-penetrating radar (3D-GPR) was employed for non-destructive, full cross-sectional detection of the pavement layer’s thickness. The antenna array spacing was optimized using the common midpoint (CMP) method, enabling precise measurement of the relative permittivity of epoxy asphalt mixtures. A significant correlation between relative permittivity and the void ratio was established, providing a novel approach to identifying areas prone to coarse segregation and early-stage water damage. Grayscale maps of the thickness distribution enabled precise detection of regions with acceptable, under-thickness and over-thickness values. The uniformity of construction thickness was quantitatively evaluated using standard deviations and coefficients of variation. Results indicated that when the coefficient exceeds 12%, improvements in the pavement construction process are necessary. This research demonstrates the capability of 3D-GPR to effectively detect thickness variations, offering a valuable tool for enhancing pavement paving and compaction practices on steel bridge decks.