Reliance of pavement texture characteristics on mix-design and compaction process

The surface texture in Hot Mix Asphalt (HMA) pavements has an important role respect to all functional performances: wet and dry friction, rolling noise generation, tire wear, and so on. The texture of a new pavement is a consequence of HMA composition (mix-design) and of construction techniques, especially considering the compaction process. While numerous studies have investigated the effect of mix design on texture, it is still unclear the effect of construction techniques. In this research, some experimental results coming from on-site investigations during the HMA construction, were processed, in order to determine the texture characteristics of pavement surfaces, in terms of mega, macro and micro-texture, using both volumetric and profilometric measures. Furthermore, the asphalt mix composition (grain size, void ratio, bulk density, percentage of bitumen, etc.) were assessed on pavement cores. Some statistical correlations between texture and asphalt mix composition were also carried out. The results confirm that the main influence on the pavement texture level is related to the aggregate maximum dimension, but also the void percentage has a significant influence. The compaction conditions, instead, seem to determine a lower effect, but nevertheless some observations can be deducted. More general, the presented research proposes some considerations, useful to improve the design of mixtures and the compaction techniques of HMA, especially in order to obtain a reduction of rolling noise generation.