 right|thumb|325px|a road in the process of being resurfaced thumb|right|325px|asphalt mixing plant is working in algeria, may 2013. road surface or pavement (american english) is the durable surface material laid down on an area intended to sustain vehicular or foot traffic, such as a road or walkway. in the past, gravel road surfaces, cobblestone and granite setts were extensively used, but these surfaces have mostly been replaced by asphalt or concrete laid on a compacted base course. road surfaces are frequently marked to guide traffic. today, permeable paving methods are beginning to be used for low-impact roadways and walkways. ==asphalt== right|thumb|237px|closeup of asphalt on a driveway  asphalt (specifically, asphalt concrete) has been widely used since the 1920s. the viscous nature of the bitumen binder allows asphalt concrete to sustain significant plastic deformation, although fatigue from repeated loading over time is the most common failure mechanism. most asphalt surfaces are laid on a gravel base, which is generally at least as thick as the asphalt layer, although some 'full depth' asphalt surfaces are laid directly on the native subgrade. in areas with very soft or expansive subgrades such as clay or peat, thick gravel bases or stabilization of the subgrade with portland cement or lime may be required. polypropylene and polyester geosynthetics have also been used for this purpose and in some northern countries, a layer of polystyrene boards have been used to delay and minimize frost penetration into the subgrade. depending on the temperature at which it is applied, asphalt is categorized as hot mix, warm mix, or cold mix. hot mix asphalt is applied at temperatures over 300Â°f (150Â°c) with a free floating screed. warm mix asphalt is applied at temperatures of 200â250Â°f (95â120Â°c), resulting in reduced energy usage and emissions of volatile organic compounds.{{cite web|url=http://www.fhwa.dot.gov/pavement/asphalt/wma.cfm|publisher=federal highway administration|accessdate=4 august 2010|date=29 october 2008
Pavements Road_hazards Road_infrastructure