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Wearing Course
The wearing course, also known as a friction course or surface course, is the upper layer in roadway, airfield, and dockyard construction. The term 'surface course' is sometimes used slightly different, to describe very thin surface layers such as chip seal. In rigid pavements the upper layer is a portland cement concrete slab. In flexible pavements, the upper layer consists of asphalt concrete, that is a construction aggregate with a bituminous binder. The wearing course is typically placed on the binder course which is then laid on the base course, which is normally placed on the subbase, which rests on the subgrade. There are various different types of flexible pavement wearing course, suitable for different situations. Stone mastic asphalt is a type of flexible pavement wearing course which is typically used for heavily trafficked roads. See also * Highway engineering * Road construction *Road surface A road surface (British English) or pavement (North American Eng ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chip Seal
Chipseal (also chip seal or chip and seal or spray seal) is a pavement surface treatment that combines one or more layers of asphalt with one or more layers of fine aggregate. In the United States, chipseals are typically used on rural roads carrying lower traffic volumes, and the process is often referred to as asphaltic surface treatment. This type of surface has a variety of other names including tar-seal or tarseal, tar and chip, sprayed seal surface dressing, or simply seal. In Australia as well as New Zealand, chipseal roads are common, including usage on major highways. Uses Chipsealing is cheaper than resurfacing an asphalt concrete or a Portland cement concrete pavement, but not as long-lasting. Installation Chipseals are constructed by evenly distributing a thin base of hot tar, bitumen or asphalt onto an existing pavement and then embedding finely graded aggregate into it. The aggregate is evenly distributed over the hot seal spray, then rolled into the bitumen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rigid Pavement
Highway engineering (also known as roadway engineering and street engineering) is a professional engineering discipline branching from the civil engineering subdiscipline of transportation engineering that involves the planning, design, construction, operation, and maintenance of roads, highways, streets, bridges, and tunnels to ensure safe and effective transportation of people and goods."Highway engineering." McGraw-Hill Concise Encyclopedia of Science and Technology. New York: McGraw-Hill, 2006. Credo Reference. Web. 13 February 2013. Highway engineering became prominent towards the latter half of the 20th century after World War II. Standards of highway engineering are continuously being improved. Highway engineers must take into account future traffic flows, design of highway intersections/interchanges, geometric alignment and design, highway pavement materials and design, structural design of pavement thickness, and pavement maintenance. History The beginning of road construc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Portland Cement Concrete
Portland cement is the most common type of cement in general use around the world as a basic ingredient of concrete, mortar, stucco, and non-specialty grout. It was developed from other types of hydraulic lime in England in the early 19th century by Joseph Aspdin, and is usually made from limestone. It is a fine powder, produced by heating limestone and clay minerals in a kiln to form clinker, and then grinding the clinker with the addition of several percent (often around 5%) gypsum. Several types of portland cement are available. The most common, historically called ordinary portland cement (OPC), is grey, but white portland cement is also available. The cement was so named by Joseph Aspdin, who obtained a patent for it in 1824, because, once hardened, it resembled the fine, pale limestone known as Portland stone, quarried from the windswept cliffs of the Isle of Portland in Dorset. Portland stone was prized for centuries in British architecture and used in iconic structu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flexible Pavement
Highway engineering (also known as roadway engineering and street engineering) is a professional engineering discipline branching from the civil engineering subdiscipline of transportation engineering that involves the planning, design, construction, operation, and maintenance of roads, highways, streets, bridges, and tunnels to ensure safe and effective transportation of people and goods."Highway engineering." McGraw-Hill Concise Encyclopedia of Science and Technology. New York: McGraw-Hill, 2006. Credo Reference. Web. 13 February 2013. Highway engineering became prominent towards the latter half of the 20th century after World War II. Standards of highway engineering are continuously being improved. Highway engineers must take into account future traffic flows, design of highway intersections/interchanges, geometric alignment and design, highway pavement materials and design, structural design of pavement thickness, and pavement maintenance. History The beginning of road construc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asphalt Concrete
Asphalt concrete (commonly called asphalt, blacktop, or pavement in North America, and Tarmacadam, tarmac or bitumen macadam in the United Kingdom and the Republic of Ireland) is a composite material commonly used to surface road 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 Construction aggregate, mineral aggregate Binder (material), bound together with bitumen (a substance also independently known as asphalt, Pitch (resin), pitch, or tar), laid in layers, and compacted. The American English terms ''asphalt'' (or ''asphaltic'') ''concrete'', ''bituminous asphalt concrete'', and ''bituminous mixture'' are typically used only in engineering and construction documents, which define concrete as any composite material composed of mineral aggregate adhered with a binder. The abbreviation, ''AC'', is sometimes used for ''asphalt concrete'' but can also denot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Construction Aggregate
Construction aggregate, or simply aggregate, is a broad category of coarse- to medium-grained particulate material used in construction. Traditionally, it includes natural materials such as sand, gravel, crushed stone. As with other types of aggregates, it is a component of composite materials, particularly concrete and asphalt. Aggregates are the most mined materials in the world,Introduction (1): What are Aggregates? « Herefordshire & Worcestershire Earth Heritage TrustIntroduction (1): What are Aggregates? « Herefordshire & Worcestershire Earth Heritage Trust, accessdate: March 23, 2017Define Aggregate at Dictionary.comaggregate accessdate: March 23, 2017 being a significant part of 6 billion tons of concrete produced per year. Aggregate serves as reinforcement to add strength to the resulting material. Due to the relatively high hydraulic conductivity as compared to most soil types, aggregates are widely used in drainage applications such as foundation and French drain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bituminous
Bitumen ( , ) is an immensely viscous constituent of petroleum. Depending on its exact composition, it can be a sticky, black liquid or an apparently solid mass that behaves as a liquid over very large time scales. In American English, the material is commonly referred to as asphalt or tar. Whether found in natural deposits or refined from petroleum, the substance is classed as a pitch. Prior to the 20th century, the term asphaltum was in general use. The word derives from the Ancient Greek word (), which referred to natural bitumen or pitch. The largest natural deposit of bitumen in the world is the Pitch Lake of southwest Trinidad, which is estimated to contain 10 million tons. About 70% of annual bitumen production is destined for road construction, its primary use. In this application, bitumen is used to bind aggregate particles like gravel and forms a substance referred to as asphalt concrete, which is colloquially termed ''asphalt''. Its other main uses lie in bit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Base Course
The base course or basecourse in pavements is a layer of material in an asphalt roadway, race track, riding arena, or sporting field. It is located under the surface layer consisting of the '' wearing course'' and sometimes an extra ''binder course''. If there is a sub-base course, the base course is constructed directly above this layer. Otherwise, it is built directly on top of the subgrade. Typical base course thickness ranges from and is governed by underlying layer properties. Generally made of a construction aggregate, it is spread and compacted to at least 95% relative compaction, thus providing a stable foundation for additional layers of material. Aggregate base (AB) is typically a mix of different sizes of crushed rock '' Aggregate Base, Class 2'', is used in roadways and consists of rock particles of size and less. An aggregate is normally made from newly quarried rock, or it is sometimes allowed to be made from recycled asphalt concrete and/or Portland cement concr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subbase (pavement)
In highway engineering, subbase is the layer of aggregate material laid on the subgrade, on which the base course layer is located. It may be omitted when there will be only foot traffic on the pavement, but it is necessary for surfaces used by vehicles. Subbase is often the main load-bearing layer of the pavement. Its role is to spread the load evenly over the subgrade. The materials used may be either unbound granular, or cement-bound. The quality of subbase is very important for the useful life of the road and can outlive the life of the surface, which can be scraped off and, after checking that the subbase is still in good condition, a new layer can be applied. Unbound granular materials are usually crushed stone, crushed slag or concrete, or slate. Cement-bound materials come in multiple types. Mass concrete is used where exceptional loads are expected, with thickness usually , and optional reinforcement with steel mesh or polymer fibers. Other cement bound materi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subgrade
In transport engineering, subgrade is the native material underneath a constructed road,http://www.highwaysmaintenance.com/drainage.htm The Idiots' Guide to Highways Maintenance ''highwaysmaintenence.com'' pavement or railway track (US: railroad track). It is also called formation level. The subgrade provides support to the subbase level and acts as an integral load-bearing layer. Failure of the subgrade can cause depressions and rutting of the upper base and surface courses. These in turn can lead to water pooling in deformations and cause vehicle aquaplaning among other issues. The term can also refer to imported material that has been used to build an embankment. Construction Subgrades are commonly compacted before the construction of a road, pavement or railway track. This is to ensure their ability to absorb the loads being transferred down from the upper layers, increasing the life and wear of the surface courses. See also * Subsoil * Track bed The track bed or t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stone Mastic Asphalt
Stone mastic asphalt (SMA), also called stone-matrix asphalt, was developed in Germany in the 1960s with the first SMA pavements being placed in 1968 near Kiel. It provides a deformation-resistant, durable surfacing material, suitable for heavily trafficked roads. SMA has found use in Europe, Australia, the United States, and Canada as a durable asphalt surfacing option for residential streets and highways. SMA has a high coarse aggregate content that interlocks to form a stone skeleton that resists permanent deformation. The stone skeleton is filled with a mastic of bitumen and filler to which fibres are added to provide adequate stability of bitumen and to prevent drainage of binder during transport and placement. Typical SMA composition consists of 70−80% coarse aggregate, 8−12% filler, 6.0−7.0% binder, and 0.3% fibre. The deformation resistant capacity of SMA stems from a coarse stone skeleton providing more stone-on-stone contact than with conventional dense graded ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Highway Engineering
Highway engineering (also known as roadway engineering and street engineering) is a professional engineering discipline branching from the civil engineering subdiscipline of transportation engineering that involves the planning, design, construction, operation, and maintenance of roads, highways, streets, bridges, and tunnels to ensure safe and effective transportation of people and goods."Highway engineering." McGraw-Hill Concise Encyclopedia of Science and Technology. New York: McGraw-Hill, 2006. Credo Reference. Web. 13 February 2013. Highway engineering became prominent towards the latter half of the 20th century after World War II. Standards of highway engineering are continuously being improved. Highway engineers must take into account future traffic flows, design of highway intersections/interchanges, geometric alignment and design, highway pavement materials and design, structural design of pavement thickness, and pavement maintenance. History The beginning of road const ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
