Sufficient pavement skid resistance is one of the essential factors to ensure traffic safety. The real contact area (Ar) between the tire and road is significant for understanding and improving the skid resistance performance. In this study, the tire–road contact area is measured by squeezing a smooth underside-dyed rubber block into the specimens, using a self-designed fixture mounted on the universal test machine. The three-dimensional (3D) printing technology is used to separate the specimens with multi-scale roughness. Surface texture on 29 AC pavements is obtained by a 3D scanner and qualified by the root-mean-square surface height (Sq), to investigate the impact of pavement texture on the Ar. The skid resistance on 23 AC road sections is measured using the T2GO system, and the pavement texture is recorded, to discuss the influence of the Ar on the skid resistance. The results indicate that the multi-scale roughness rarely affects the measured contact area once the concerned wavelength is less than 0.6 mm. The Ar decreases with the Sq following a power function but has weak correlation with the friction coefficient. This study could provide an in-depth understanding of the tire–road contact and lays a foundation for optimizing the contact-related pavement performance.

The asphalt pavement texture is vertical asymmetric, and the tread rubber may contact part of pavement surface. Therefore, the tread penetration depth (d) is probably essential for developing a reliable relationship between pavement performance and texture. This study investigated the effect of pavement on d, and simplified the contact by squeezing a rubber plate into three-dimensional (3D)-printing specimens. The 44 specimens were manufactured based on the surface morphologies of pavements and artificial surfaces with characteristics of pavement texture. The specimens’ surfaces were characterised by parameters from ISO-25178. A set of self-designed fixture was mounted on a loading machine to exert precise force. The contact area was recorded by leaving the stain attached to the rubber plate on the specimens’ surface. The value of d was obtained based on the specimens' Abbott–Firestone curves and the measured contact area. The results showed that the parameters focusing on the top topography of the pavement surface always exhibited a strong positive correlation with d. Furthermore, the parameter representing the volume of peak material showed almost the strongest linear relationship with d. The intercept and slope of the linear equations increased with the increase in the loading pressure or decline in the rubber hardness.

Three-dimensional (3D) parameters are being increasingly used to characterise the pavement macrotexture. This study explores the influence of the evaluation area and sampling interval on the 3D macrotexture parameters. The point clouds of surfaces with different morphologies are captured by a 3D scanner, and is divided into non-overlapping rectangular areas with different sizes. The original point clouds are diluted to obtain data with different sampling intervals. The parameters concerned include the root-mean-square surface height Sq, the root-mean-square surface slope Sdq, the peak density Spd, the arithmetic mean principal curvature Spc, the volume of the peak material Vmp and the volume of the core material Vmc. The results indicate that parameters calculated within an evaluation area of 80*80 mm² can properly represent the macrotexture. The sampling interval influence parameters in the order Spc > Spd > Sdq > Sq, Vmp, Vmc. The conclusions lay the foundation for calculating 3D pavement parameters.

Maintaining good friction performance of highway pavement is important for road safety. The friction is affected by many factors, and the present study investigates the effect of the compactness on the texture and friction of asphalt concrete during the polishing process. Two three-dimensional (3D) texture parameters and the mean texture depth (MTD) were used to characterize the surface texture of AC-13 asphalt concrete. The differences of surface texture are then being analyzed among the pavement in the field, rutting slabs with 97% compactness (RS-97), rutting slabs with 100% compactness (RS-100), and rutting slabs with 103% (RS-103). The rutting slabs were polished by a circular vehicle simulator (CVS). The 3D surface topography, British pendulum number (BPN), and MTD were obtained during the polishing process. Test results show that the surface of the rutting slab can be smoother as the compactness increased from 97% to 103%. During the whole polishing process, the rutting slab with smaller compactness had higher value of the MTD. The impact of compactness on the BPN is insignificant during the polishing process, but rutting slabs with smaller compactness had better friction at high speed as the result of the higher MTD.