Skid Resistance of Asphalt Concrete at the Construction Stage Based on Thai Aggregates

In Thailand, the skid resistance in road pavements requires considerable improvement in order to increase road network safety. However, skid-resistance values can only be measured in situ, that is on the road itself, and prior to post-construction stages. So, skid-resistance values have not been accounted for during the aggregate selection and mixing processes. In this study, a skid-resistance predictive model at the construction stage was developed based on the essential aggregate and mixture characteristics that are the influential factors. Three main types of Thai aggregates (limestone, granite, and basalt) were mixed in asphalt concrete to make the pavement for the construction sites, which were sourced and collected to make test asphalt concrete. These aggregates were obtained from Thailand’s main regions and covered 14 provinces, with 90 projects for mean texture depth test and 110 projects for skid-resistance test, to provide accurate representation. Aggregates and their standard densely-graded asphalt concrete mixtures of 9.5 and 12.5 mm maximum aggregate sizes were used to perform in the construction site. The skid-resistance value (SRV) was measured by a pendulum tester. In addition, the textural characteristics of asphalt concrete pavement, based on different aggregate mixtures, were also analyzed with respect to a sand patch method. The results of the study demonstrated that the developed predictive model in terms of aggregates and mixture characteristics (polished stone value, gradation, and mixture surface texture) provided acceptable SRV prediction with high statistic levels [$R$-square $(R^2)>0.78$, mean square error (MSE) $<0.00089$ and F-significance $<0.05$]. The model will be put forward for inclusion in the preventive scheme for road safety management by the Department of Rural Roads, Thailand.