Pavement (American English) or road surface (British English) is the durable surface material laid down on an area intended to sustain traffic (vehicular or foot traffic). Phonology North American English regional phonology In many ways compared to English English, North American English is conservative in its Phonology. British English or UK English ( BrE, BE, en-GB) is the broad term used to distinguish the forms of the English language used in the Such surfaces are frequently marked to guide traffic. Road surface marking is any kind of device or material that is used on a road surface in order to convey official information The most common modern paving methods are asphalt and concrete. Asphalt ( is a sticky black and highly viscous liquid or semi-solid that is present in most crude Petroleums and in some natural deposits sometimes termed asphaltum Concrete is a construction material composed of Cement (commonly Portland cement) as well as other cementitious materials such as Fly ash and Slag In the past, brick was extensively used, as was metaling. Today, permeable paving methods are beginning to be used more for low-impact roadways and walkways. Permeable paving, is different than pervious paving or porous pavement, by virtue of the fact that rainwater passes around the paver as opposed to passing through

Metalling

Metal or metalling has had two distinct usages in road paving. Metalling originally referred to the process of creating a carefully engineered gravel roadway. The route of the roadway first would be dug down several feet. Depending on local conditions, French drains may or may not have been added. A French drain, drain tile, or land drain is a Ditch filled with Gravel or rock that Redirects surface and Ground Next, large stone was placed and compacted, followed by successive layers of smaller stone, until the road surface was a small stone compacted into a hard, durable surface.

Road metal later became the name of stone chippings mixed with tar to form the road surfacing material tarmac. In Geology, rock is a naturally occurring aggregate of Minerals and/or Mineraloids The Earth's outer solid layer the ‘ Lithosphere Tar is a viscous black Liquid derived from the Destructive distillation of organic matter Tarmac (short for tarmacadam, a Portmanteau for Tar -penetration Macadam) is a type of highway surface, pioneered by John A road of such material is called a "metalled road" in British usage, or less often a macadam road. Macadam is a type of Road construction pioneered by the Scotsman John Loudon McAdam in around 1820 The word metal is derived from the Latin metallum, which means both "mine" and "quarry", hence the roadbuilding terminology. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome.

Asphalt paving

A road in the process of being resurfaced, showing both old and new asphalt surfaces.

Asphalt (specifically, asphalt concrete) has been widely used since 1920-1930, though in ancient times asphalt was already used for road-building. Asphalt concrete, normally known simply as Asphalt, is a Composite material commonly used for construction of pavement, Highways and Asphalt ( is a sticky black and highly viscous liquid or semi-solid that is present in most crude Petroleums and in some natural deposits sometimes termed asphaltum 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. Bitumen is a mixture of organic Liquids that are highly Viscous, black sticky entirely soluble in Carbon disulfide, and composed primarily In Materials science, deformation is a change in the shape or size of an object due to an applied force. Most asphalt pavements are built on a gravel base which is generally at least as thick as the asphalt layer, although some 'full depth' pavements are built directly on the native subgrade. In Highway engineering, subgrade is the native material underneath a constructed pavement 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 can be required. Clay is a naturally occurring material composed primarily of fine-grained Minerals which show plasticity through a variable range of Water content, and Peat is an accumulation of partially Decayed Vegetation matter. Portland cement is the most common type of Cement in general usage in many parts of the world as it is a basic ingredient of Concrete, mortar, Stucco Lime is a general term for various naturally occurring Minerals and materials derived from them in which Carbonates Oxides and Hydroxides of In some countries with soft soils, a foundation of polystyrene blocks is used instead. Soil, often typeset as SOiL, is a four piece rock band from Chicago Illinois United States founded by Shaun Glass Tom Schofield Tim King and Adam Zadel A foundation is a Structure that transfers loads to the earth Polystyrene ˌpɒliˈstaɪriːn ( IUPAC Polyphenylethene is an aromatic Polymer made from the aromatic Monomer Styrene The actual material used in paving is termed HMA (Hot Mix Asphalt), and it is usually applied using a free floating screed. The free floating screed is a device pioneered by Barber Greene Company in the 1930s that revolutionized the Asphalt paving process

Advantages of asphalt roadways include relatively low noise, relatively low cost compared with other paving methods, and ease of repair. Disadvantages include less durability than other paving methods, less tensile strength than concrete, the tendency to become slick and soft in hot weather and a certain amount of hydrocarbon pollution to soil and groundwater or waterways. In Organic chemistry, a hydrocarbon is an Organic compound consisting entirely of Hydrogen and Carbon. Groundwater is Water located beneath the Ground surface in Soil pore spaces and in the Fractures of lithologic formations A waterway is any navigable Body of water. These include Rivers Lakes Seas Oceans and Canals In order for a waterway

Concrete paving (white paving)

Concrete pavements (specifically, Portland cement concrete) are created using a concrete mix of Portland cement, gravel, and sand. Portland cement is the most common type of Cement in general usage in many parts of the world as it is a basic ingredient of Concrete, mortar, Stucco Gravel is rock that is of a specific Particle size range In Geology, gravel is any loose rock that is larger than two millimeters (2mm Sand is a naturally occurring Granular material composed of finely divided rock and Mineral particles The material is applied in a freshly-mixed slurry, and worked mechanically to compact the interior and force some of the thinner cement slurry to the surface to produce a smoother, denser surface free from honeycombing.

Concrete pavements have been refined into three common types: jointed plain (JPCP), jointed reinforced (JRCP) and continuously reinforced (CRCP). The one item that distinguishes each type is the jointing system used to control crack development.

Jointed Plain Concrete Pavements (JPCP) contain enough joints to control the location all of the expected natural cracks. The concrete cracks at the joints and not elsewhere in the slabs. Jointed plain pavements do not contain any steel reinforcement. However, there may be smooth steel bars at transverse joints and deformed steel bars at longitudinal joints. The spacing between transverse joints is typically about 15 feet for slabs 7-12 inches thick. Today, a majority of the U. S. state agencies build jointed plain pavements.

Jointed Reinforced Concrete Pavements (JRCP) contain steel mesh reinforcement (sometimes called distributed steel). In jointed reinforced concrete pavements, designers increase the joint spacing purposely, and include reinforcing steel to hold together intermediate cracks in each slab. The spacing between transverse joints is typically 30 feet or more. In the past, some agencies used a spacing as great as 100 feet. During construction of the interstate system, most agencies in the Eastern and Midwestern U. S. built jointed-reinforced pavement. Today only a handful of agencies employ this design, and its use is generally not recommended as JPCP and CRCP offer better performance and are easier to repair.

Continuously Reinforced Concrete Pavements (CRCP) does not require any transverse contraction joints. Transverse cracks are expected in the slab, usually at intervals of 3-5 ft. CRCP pavements are designed with enough steel, 0. 6-0. 7% by cross-sectional area, so that cracks are held together tightly. Determining an appropriate spacing between the cracks is part of the design process for this type of pavement.

Continuously reinforced designs generally cost more than jointed reinforced or jointed plain designs initially due to increased quantities of steel. However, they can demonstrate superior long-term performance and cost-effectiveness. A number of agencies choose to use CRCP designs in their heavy urban traffic corridors.

Advantages of cement concrete roadways include that they are typically stronger and last longer than asphalt concrete pavements. They also can easily be grooved to provide a durable skid-resistant surface. Disadvantages are that they have a higher initial cost, are more difficult to repair, and are also somewhat noisy if jointed, but unjointed concrete pavement is actually a method of roadway noise mitigation. Roadway noise is the collective sound energy emanating from Motor vehicles In the USA it contributes more to environmental noise exposure than any other noise source and is Noise mitigation is a set of strategies to reduce Noise pollution.

Additionally, in areas with cold winters, road salt can damage concrete roadbeds; due to the high cost of replacing the bed, exposed concrete roadbeds are infrequently seen in areas with harsh winters. However, reinforced concrete slabs are more resistant to frost-related ground heaves and pothole formation; heavily used roads in winter-prone urban areas often have concrete roadbeds covered with a thin (3cm) layer of asphalt concrete. This layer can be "skimmed off" and replaced very cheaply when it wears and deteriorates, while the concrete beneath is protected from the harsh elements. In these conditions, concrete roadbeds can last upwards of 50 years when a pure asphalt roadbed is expected to need to be completely replaced several times in this time period, offsetting the higher initial cost.

The first street in the United States to be paved with concrete is Court Avenue in Bellefontaine, Ohio, but the record for first mile of concrete pavement to be laid in the United States is claimed by Michigan. Bellefontaine (pronounced bell-FOUN-tin bɛlˈfaʊntɨn is a city in and the County seat of Logan County, Ohio, United States. The Michigan Department of Transportation ( MDOT) is a constitutional Government agency in the U

Bituminous Surface Treatment (BST)

Concrete pavers

Bituminous Surface Treatment (BST) is used mainly on low-traffic roads, but also as a sealing coat to rejuvenate an asphalt concrete pavement. It generally consists of aggregate spread over a sprayed-on asphalt emulsion or cut-back asphalt cement. An emulsion ( IPA: /ɪˈmʌlʃən/ is a mixture of two Immiscible (unblendable liquids The aggregate is then embedded into the asphalt by rolling it, typically with a rubber-tired roller. A road roller (sometimes called a roller-compactor, or just roller) is a Compactor type Engineering vehicle used to compact soil BSTs of this type are described by a wide variety of regional terms including "chip seal", "tar and chip", "oil and stone", "seal coat" or "surface dressing". Chip Seal is a pavement surface treatment that combines a layer of Asphalt with a layer of fine aggregate.

BST is used on hundreds of miles of the Alaska Highway and other similar roadways in Alaska, the Yukon Territory, and northern British Columbia. The Alaska Highway (also known as the Alaskan Highway, Alaska-Canadian Highway, or ALCAN Highway) was constructed during World War II and connects Alaska ( Аляска Alyaska) is a state in the United States of America, in the northwest of the North American continent Yukon (ˈjuːkɒn is the westernmost and smallest of Canada's three territories. British Columbia (ˌbrɪtɨʃ kəˈlʌmbiə ( BC) ( (la Colombie-Britannique C The ease of application of BST is one reason for its popularity, but another is its flexibility, which is important when roadways are laid down over unstable terrain that thaws and softens in the spring.

Other types of BSTs include micropaving, slurry seals and Novachip. These are laid down using specialized and proprietary equipment. They are most often used in urban areas where the roughness and loose stone associated with chip seals is considered undesirable.

Other paving methods

A brick main street in Lebanon, Illinois

Pavers, generally in the form of pre-cast concrete blocks, are often used for aesthetic purposes, or sometimes at port facilities that see long-duration pavement loading. Lebanon is a city in St Clair County, Illinois, United States. A harbor or harbour (see spelling differences) or haven, is a place where ships may shelter from the Weather or are stored Pavers are rarely used in areas that see high-speed vehicle traffic.

Brick, cobblestone and wood plank pavements were once common in urban areas throughout the world, but due to their high manual labor requirements they are in some countries typically only maintained for historical reasons, while in other countries they are still common in local streets. A brick is a block of Ceramic material used in Masonry construction laid using mortar. Cobblestones are stones that were frequently used in the pavement of early Streets "Cobblestone" is derived from the very old English word "cob" Wood is hard fibrous lignified structural tissue produced as secondary Xylem in the stems of Woody plants notably trees but also shrubs They make maintenance of cabling and pipelines under the pavement easier but are also harder to walk on.

Likewise, macadam and tarmac pavements can still sometimes be found buried underneath asphalt concrete or Portland cement concrete pavements, but are rarely constructed anymore. Macadam is a type of Road construction pioneered by the Scotsman John Loudon McAdam in around 1820 Tarmac (short for tarmacadam, a Portmanteau for Tar -penetration Macadam) is a type of highway surface, pioneered by John

Acoustical implications

Roadway surfacing choices are known to affect the intensity and spectrum of sound emanating from the tire/surface interaction. ^[1] Initial applications of this knowledge occurred in the early 1970s. Roadway surface types contribute differential noise effects of up to four dB, with chip seal type and grooved roads being the loudest and concrete surfaces without spacers being the quietest. Asphaltic surfaces perform intermediately relative to concrete and chip seal. Asphalt ( is a sticky black and highly viscous liquid or semi-solid that is present in most crude Petroleums and in some natural deposits sometimes termed asphaltum Chip Seal is a pavement surface treatment that combines a layer of Asphalt with a layer of fine aggregate. These phenomena are, of course, highly influenced by vehicle speed.

Cobbles

Although this is a wall, this image shows a common pattern for pavement, in the symmetry category "wallpaper group cmm"; the same pattern is possible with other length/width ratios; square tiles are also common

Bricks in a Herringbone pattern, in the symmetry category "wallpaper group pgg"; the same pattern is possible with any length/width ratio

Street pavement in Zakopane, Poland in the symmetry category "wallpaper group p3"

Pavement deterioration

As pavement systems primarily fail due to fatigue (in a manner similar to metals), the damage done to pavement increases with the fourth power of the axle load of the vehicles traveling on it. A wallpaper group (or plane symmetry group or plane crystallographic group) is a mathematical classification of a two-dimensional repetitive pattern based on the A wallpaper group (or plane symmetry group or plane crystallographic group) is a mathematical classification of a two-dimensional repetitive pattern based on the Zakopane is a town in southern Poland with some 28000 inhabitants (2004 situated in Lesser Poland Province since 1999 (in 1975–98 it was part of Nowy Poland (Polska officially the Republic of Poland A wallpaper group (or plane symmetry group or plane crystallographic group) is a mathematical classification of a two-dimensional repetitive pattern based on the The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across Civil Engineers consider truck axle load, current and projected truck traffic volume, supporting soil properties and sub-grade drainage in design. A civil engineer is a person who practices Civil engineering, one of the many engineering professions Soil, often typeset as SOiL, is a four piece rock band from Chicago Illinois United States founded by Shaun Glass Tom Schofield Tim King and Adam Zadel Drainage is the natural or artificial removal of surface and sub-surface water from a given area Passenger cars are considered to have no practical effect on a pavement's service life, from a fatigue perspective.

Other pavement failure modes include ageing and surface abrasion. As years go by, the binder in a bituminous wearing course gets stiffer and less flexible. When it gets "old" enough, the surface will start loosing aggregates, and macrotexture depth increases dramatically. Macrotexture (MaTx has wavelengths from 05 mm up to 50 mm Short wave macrotexture is a family of surface properties that reduce road traffic noise If no maintenance action is done quickly on the wearing course (seal coating, surface dressing, etc. ), potholing will take place. In areas with cold climate, studded tires may be allowed on passenger cars. In Sweden and Finland, studded passenger car tires account for a very large share of pavement rutting.

Several pavement design methods have been developed to determine the thickness and composition of pavement required to carry predicted traffic loads for a given period of time. Pavement design methods are continuously evolving. Among these are the Shell Pavement design method, and the American Association of State Highway and Transportation Officials (AASHTO) 1993 "Guide for Design of Pavement Structures". The Shell Pavement design method is used in many Countries for the design of new Asphalt Roads The main input consists of Soil Parameters AASHTO, the American Association of State Highway and Transportation Officials, is a standards setting body which publishes specifications test protocols and A new mechanistic-empirical design guide has been under development by NCHRP (Called Superpave Technology) since 1998. A new design guide called Mechanistic Empirical Pavement Design Guide (MEPDG) was developed and is about to be adopted by AASHTO.

According to the AASHO Road Test, heavily loaded trucks can do more than 10,000 times the damage done by a normal passenger car. The AASHO Road Test was a series of experiments carried out by the American Association of State Highway and Transportation Officials to determine how traffic contributed to This article is about the semi-truck For the North American use of the word see Pickup truck. Tax rates for trucks are higher than those for cars in most countries for this reason, though they are not levied in proportion to the damage done. ^[2]

The physical properties of a stretch of pavement can be tested using a falling weight deflectometer. A falling weight deflectometer, FWD is a testing device used by Civil engineers to evaluate the physical properties of a pavement.

Further research by University College London into pavements has led to the development of an indoor, 80-sq-metre artificial pavement at a research centre called Pedestrian Accessibility and Movement Environment Laboratory (PAMELA). University College London ( UCL) is a multi-faculty university institution based in the United Kingdom and a constituent college of the University of London The Pedestrian Accessibility and Movement Environment Laboratory (PAMELA is an indoor 80 sq metre artificial pavement at a research center at University College London It is used to simulate everyday scenarios, from different pavement users to varying pavement conditions. ^[3]

See also

• Road
• Street

Line notes

References

• When to pave a gravel road