Physical properties of multi-layer seal surfacing in Turkey

Seal surfacing is frequently used on low-volume roads throughout the world. However, seal surfacing is also used on high-volume roads in Turkey. Seventy-nine percent of the total amount of road length for which the General Directorate of Turkish Highways is responsible is coated with seal surfacing, and most of the 15 000 km of divided roads under construction are projected to be seal-surfacing roads. For this reason, there is a need for more information about seal surfacing. Within the context of the present study, the state and provincial roads located in the south-western part of Anatolia were investigated and core samples were taken from multi-layered seal-surfacing pavements. The core samples were fixed in size to match the standard Marshall sample size. The physical characteristics were defined by carrying out unit weight tests, ultrasound tests and Marshall stability tests. Skid resistance tests were performed around the core extraction areas on the road surfaces. In order to conduct analyses of the binder portions and the aggregate portions of the core samples, binder was extracted from the core samples through the use of a centrifuge extractor. As a consequence, attempts were made to determine the physical characteristics and actual conditions of multi-layer seal surfacing. In conclusion, it emerged that in the case of both building techniques and material characteristics, seal surfacing differs from hot mix asphalt. However, multi-layer seal surfacing demonstrates properties that are similar to those of hot mix asphalt. It must be taken into consideration that there are significant differences in stability and yield values.