In this study, numerical simulations using the Abaqus finite element model were performed to evaluate the effects of incorporating waste tyres of varying sizes into the base layer as part of a coupled tyre–pavement structure. The tyre-reinforced structure demonstrated superior deformation resilience, attributed to the hyperelastic properties of tyre rubber, underscoring its potential for applications where deformation recovery is essential. For achieving a uniform settlement, the entire tyre stacking scheme is recommended, whereas the one-third tyre configuration is ideal for minimising displacement. The one-half tyre configuration provides a balanced approach, optimising resource utilisation for structures with moderate performance requirements. The inclusion of tyres increases the equivalent stress within the cement-stabilised gravel layer beneath the tyre, and this effect is less pronounced with smaller tyre sizes. Notably, the projected portion of the tyre tread enhances the bearing capacity of the base structure, improving the load distribution and overall structural performance. The middle and bottom surface layers were identified as the most critical for controlling deformation and stress distribution, while a moderate modulus is advised for the surface course to achieve a balance between deformation control and stress uniformity. The integration of high-modulus layers with tyre reinforcement offers an optimised solution for both deformation management and stress distribution. This study highlights the potential of tyre-reinforced pavements as an innovative and sustainable construction practice, particularly suited for light to moderate traffic conditions. Further research is recommended to explore the long-term environmental and economic benefits, as well as the impacts of tyre composition and ageing on performance.

This study proposes a non-contact framework for evaluating the skid resistance of shared roadside pavements to improve cyclist and pedestrian safety. By integrating a friction tester and a laser scanner, we synchronize high-resolution three-dimensional (3D) surface texture characterization with friction coefficient measurements under dry and wet conditions. Key metrics—including fractal dimension (FD), macro/micro-texture depth density (HL_TX and WL_TX), mean texture depth (MTD), and joint dimensions—were derived from 3D laser scans. A hierarchical regression analysis was employed to prioritize the influence of texture and joint parameters on skid resistance across environmental conditions. Combined with material types (brick, tile, and stone) and drainage performance, these metrics are systematically analyzed to quantify their correlations with skid resistance. Results indicate that raised macro-textures and high FD (>2.5) significantly enhance dry-condition skid resistance, whereas recessed textures degrade performance. The hierarchical model further reveals that FD and MTD dominate dry friction (β = 0.61 and −0.53, respectively), while micro-texture density (WL_TX) and seam depth are critical predictors of wet skid resistance (β = −0.76 and 0.31). In wet environments, skid resistance is dominated by micro-texture density (WL_TX < 3500) and macro-texture-driven water displacement, with higher WL_TX values indicating denser micro-textures that impede drainage. The study validates that non-contact laser scanning enables efficient mapping of critical texture data (e.g., pore connectivity, joint depth ≥0.25 mm) and friction properties, supporting rapid large-scale pavement assessments. These findings establish a data-driven linkage between measurable surface indicators (texture, morphometry, drainage) and skid resistance, offering a practical foundation for proactive sidewalk safety management, especially in high-risk areas. Future work should focus on refining predictive models through multi-sensor fusion and standardized design guidelines.

To address the issue of cracking damage under extreme high-temperature rutting, which is not sufficiently considered in the selection of preventive maintenance programs, the objective of this study was to investigate the preventive maintenance-oriented minor internal damage changes in asphalt concrete with a normal maximum aggregate size of 16 mm (AC-16) under extreme high temperature (70 °C) and load (1.4 MPa) conditions. The changes in void structure within the 0–10 mm rutting depth were tracked through the rutting test and Computer Tomography (CT) image analysis. It was observed that there were notable discrepancies in the three-dimensional (3D) space distribution of void, void volume development, and void morphology between the rut impact zones and the rutted part. The impact zone exhibited a greater prevalence of voids and an earlier onset of cracking. At a rutting depth of only 5 mm, multiple top-down developed cracks (TDCs) of over 6 mm length were observed in the impact zone. At a rutting depth of 10 mm, the TDCs in the impact zone were more numerous, larger, and wider, indicating the necessity for a tailored repair program that includes milling. TDC damage caused by high-temperature rutting is predominantly observed in the upper and middle positions of the height direction, with the bottom position data exhibiting greater inconsistency due to the influence of molding. Furthermore, the combination of void morphology indicators with void volume can effectively track the occurrence and development of microcracks. However, the fine-scale assessment of compaction degree and deformation process using the equivalent void diameter indicator is not sufficiently differentiated.

Conventional maintenance models often neglect the impact of pre-existing rutting on sealcoat performance, particularly in high-temperature regions like Chongqing in China, where rut-related failures are common. Existing ruts impose geometric constraints that significantly alter stress redistribution within the new sealcoat layer, yet this constraint mechanism remains poorly understood due to limitations in laboratory observation. This study developed a mesoscopic AC16 + MS3 composite discrete element model to simulate the mechanical behavior of a sealcoat applied over a rutted pavement. To replicate real-world conditions, a constant pressure of 0.7 MPa, representing the standard tire ground pressure in JTG E20-2011, was applied at a temperature of 70 °C, reflecting extreme high-temperature stability limits. Virtual rutting tests and contact force chain analyses were conducted across varying existing pavement rut depths, including 0 mm, 3 mm, 6 mm, and 10 mm. The results indicate that existing ruts redirect stress transfer paths, causing vertical compressive force chains to densify within the rutted zone and tensile stress to concentrate at rut edges. Mastic-mastic contacts transmit over 65% of the load, identifying asphalt mortar as the primary load-transfer phase. Notably, a 10 mm existing rut depth induces a tensile vacuum zone at depths of 15–40 mm, disrupting the standard U-shaped stress distribution. These findings clarify how pre-existing geometries govern structural degradation, suggesting that maintenance in high-temperature regions must prioritize asphalt mortar performance to mitigate edge cracking and deformation.