Field investigation of skid resistance degradation of asphalt pavement during early service

This paper documents a field investigation into the skid resistance degradation of asphalt pavement during early service. Field tests were conducted 7 times during more than 2 years. There are 2 highway sections included in the field tests, which cover 4 asphalt surface types, i.e., dense asphalt concrete (DAC), rubber asphalt concrete (RAC), stone matrix asphalt (SMA), and ultra-thin wearing course (UTWC). Macrotexture and friction data were collected using the sand patch method and the dynamic friction tester respectively. The degradation of the mean texture depth (MTD) and the friction coefficient at slip speed of 60 km/h (DFT60) were analyzed. The international friction index (IFI) was also calculated using the friction coefficient at slip speed of 20 km/h (DFT20) with MTD to evaluate the skid resistance degradation. The UTWC has relatively good skid resistance even after 7.4 × 106 standard vehicle passes. The SMA has very stable friction performance which maintains almost the same friction level after 4.61 × 106 standard vehicle passes. The DAC and RAC have relatively poor friction performance while the RAC has better macrotexture. The changing trends of skid resistance with traffic wear can be fitted by a logarithmic model for all surface types. The SMA and UTWC have relatively clear relationship between DFT20 and MTD, while the RAC and the DAC show more complex.