Asphalt concrete, commonly called asphalt, blacktop, or pavement in North America, and tarmac or bitumen macadam in the United Kingdom and the Republic of Ireland, is a composite material commonly used to surface roads, parking lots, airports, and the core of embankment dams. Asphalt mixtures have been used in pavement construction since the nineteenth century. It consists of mineral aggregate bound together with bitumen ( a substance also independently known as asphalt, pitch, or tar ), laid in layers, and compacted. Different types of asphalt concrete have different performance characteristics in roads in terms of surface durability, tire wear, braking efficiency and roadway noise. In principle, the determination of appropriate asphalt performance characteristics must take into account the volume of traffic in each vehicle category, and the performance requirements of the friction course.Transylvania or Ardeal is a historical and cultural region in Central Europe, encompassing central Romania. To the east and south its natural border are the Carpathian Mountains and to the west the Apuseni Mountains.
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