Asphalt concreteAsphalt 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 beginning of the twentieth century. It consists of mineral aggregate bound together with bitumen (also known as asphalt), laid in layers, and compacted.
BitumenBitumen (ˈbɪtjʊmɪn, bɪˈtjuːmən,_baɪ-) is a sticky, black, highly viscous liquid or semi-solid form of petroleum. In the U.S., it is commonly referred to as asphalt. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term asphaltum was also used. The word is derived from the ancient Greek ἄσφαλτος ásphaltos. The largest natural deposit of bitumen in the world, estimated to contain 10 million tons, is the Pitch Lake in southwest Trinidad.
Road surfaceA road surface (English), or pavement (American), 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past, gravel road surfaces, macadam, hoggin, cobblestone and granite setts were extensively used, but these have mostly been replaced by asphalt or concrete laid on a compacted base course. Asphalt mixtures have been used in pavement construction since the beginning of the 20th century and are of two types: metalled (hard-surfaced) and unmetalled roads.
ConcreteConcrete is a composite material composed of aggregate bonded together with a fluid cement that cures over time. Concrete is the second-most-used substance in the world after water, and is the most widely used building material. Its usage worldwide, ton for ton, is twice that of steel, wood, plastics, and aluminium combined. When aggregate is mixed with dry Portland cement and water, the mixture forms a fluid slurry that is easily poured and molded into shape.
Types of concreteConcrete is produced in a variety of compositions, finishes and performance characteristics to meet a wide range of needs. Modern concrete mix designs can be complex. The choice of a concrete mix depends on the need of the project both in terms of strength and appearance and in relation to local legislation and building codes. The design begins by determining the requirements of the concrete. These requirements take into consideration the weather conditions that the concrete will be exposed to in service, and the required design strength.
Mathematical optimizationMathematical optimization (alternatively spelled optimisation) or mathematical programming is the selection of a best element, with regard to some criterion, from some set of available alternatives. It is generally divided into two subfields: discrete optimization and continuous optimization. Optimization problems arise in all quantitative disciplines from computer science and engineering to operations research and economics, and the development of solution methods has been of interest in mathematics for centuries.
Oil sandsOil sands, tar sands, crude bitumen, or bituminous sands, are a type of unconventional petroleum deposit. Oil sands are either loose sands or partially consolidated sandstone containing a naturally occurring mixture of sand, clay, and water, soaked with bitumen, a dense and extremely viscous form of petroleum. Significant bitumen deposits are reported in Canada, Kazakhstan, Russia, and Venezuela. The estimated worldwide deposits of oil are more than ; Proven reserves of bitumen contain approximately 100 billion barrels, and total natural bitumen reserves are estimated at worldwide, of which , or 70.
Convex optimizationConvex optimization is a subfield of mathematical optimization that studies the problem of minimizing convex functions over convex sets (or, equivalently, maximizing concave functions over convex sets). Many classes of convex optimization problems admit polynomial-time algorithms, whereas mathematical optimization is in general NP-hard.
RappingRapping (also rhyming, flowing, spitting, emceeing or MCing) is a musical form of vocal delivery that incorporates "rhyme, rhythmic speech, and street vernacular". It is performed, usually over a backing beat or musical accompaniment. The components of rap include "content" (what is being said e.g. lyrics), "flow" (rhythm, rhyme), and "delivery" (cadence, tone). Rap differs from spoken-word poetry in that it is usually performed off-time to musical accompaniment. Rap is a primary ingredient of hip hop music commonly associated with that genre.
Tar pitTar pits, sometimes referred to as asphalt pits, are large asphalt deposits. They form in the presence of oil, which is created when decayed organic matter is subjected to pressure underground. If this crude oil seeps upward via fractures, conduits, or porous sedimentary rock layers, it may pool up at the surface. The lighter components of the crude oil evaporate into the atmosphere, leaving behind a black, sticky asphalt. Tar pits are often excavated because they contain large fossil collections.
