Asphalt
Channel: 宇宙のすべての知識 プリンシピア
Date: 2018-12-23

Asphalt, by Wikipedia https://en.wikipedia.org/wiki?curid=657 / CC BY SA 3.0

Asphalt

Asphalt, also known as bitumen (, ), is a sticky, black, and highly viscous liquid or semi-solid form of petroleum. 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 primary use (70%) of asphalt is in road construction, where it is used as the glue or binder mixed with aggregate particles to create asphalt concrete. Its other main uses are for bituminous waterproofing products, including production of roofing felt and for sealing flat roofs.

The terms "asphalt" and "bitumen" are often used interchangeably to mean both natural and manufactured forms of the substance. In American English, "asphalt" (or "asphalt cement") is commonly used for a refined residue from the distillation process of selected crude oils. Outside the United States, the product is often called "bitumen", and geologists worldwide often prefer the term for the naturally occurring variety. Common colloquial usage often refers to various forms of asphalt as "tar", as in the name of the La Brea Tar Pits.

Naturally occurring asphalt is sometimes specified by the term "crude bitumen". Its viscosity is similar to that of cold molasses while the material obtained from the fractional distillation of crude oil boiling at is sometimes referred to as "refined bitumen". The Canadian province of Alberta has most of the world's reserves of natural asphalt in the Athabasca oil sands, which cover , an area larger than England.

The word "asphalt" is derived from the late Middle English, in turn from French "asphalte", based on Late Latin "asphalton", "asphaltum", which is the latinisation of the Greek ἄσφαλτος ("ásphaltos", "ásphalton"), a word meaning "asphalt/bitumen/pitch", which perhaps derives from ἀ-, "without" and σφάλλω ("sfallō"), "make fall". The first use of asphalt by the ancients was in the nature of a cement for securing or joining together various objects, and it thus seems likely that the name itself was expressive of this application. Specifically, Herodotus mentioned that bitumen was brought to Babylon to build its gigantic fortification wall. From the Greek, the word passed into late Latin, and thence into French ("asphalte") and English ("asphaltum" and "asphalt"). In French, the term "asphalte" is used for naturally occurring asphalt-soaked limestone deposits, and for specialised manufactured products with fewer voids or greater bitumen content than the "asphaltic concrete" used to pave roads.

The expression "bitumen" originated in the Sanskrit words "jatu", meaning "pitch", and "jatu-krit", meaning "pitch creating" or "pitch producing" (referring to coniferous or resinous trees). The Latin equivalent is claimed by some to be originally "gwitu-men" (pertaining to pitch), and by others, "pixtumens" (exuding or bubbling pitch), which was subsequently shortened to "bitumen", thence passing via French into English. From the same root is derived the Anglo-Saxon word "cwidu" (mastix), the German word "Kitt" (cement or mastic) and the old Norse word "kvada".

In British English, "bitumen" is used instead of "asphalt". The word "asphalt" is instead used to refer to asphalt concrete, a mixture of construction aggregate and asphalt itself (also called "tarmac" in common parlance). Bitumen mixed with clay was usually c...