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ASPHALT (/ˈæsˌfɔːlt, -ˌfɑːlt/ ), also known as BITUMEN (UK English: /ˈbɪtʃəmən, ˈbɪtjʊmən/ , US English: /bɪˈt(j)uːmən, baɪˈt(j)uːmən/ ) 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
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
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 525 °C (977 °F) is sometimes referred to as "refined bitumen". The Canadian province of Alberta
Alberta
has most of the world's reserves of natural asphalt in the Athabasca oil sands , which cover 142,000 square kilometres (55,000 sq mi), an area larger than England .

CONTENTS

* 1 Terminology

* 1.1 Etymology * 1.2 Modern terminology

* 2 Composition * 3 Occurrence

* 4 History

* 4.1 Ancient times * 4.2 Continental Europe * 4.3 United Kingdom * 4.4 United States * 4.5 Canada * 4.6 Photography and art

* 5 Modern use

* 5.1 Global use * 5.2 Rolled asphalt concrete * 5.3 Mastic asphalt * 5.4 Asphalt
Asphalt
emulsion * 5.5 Synthetic crude oil * 5.6 Non-upgraded crude bitumen * 5.7 Radioactive waste encapsulation matrix * 5.8 Other uses

* 6 Production

* 6.1 Oil sands * 6.2 Alternatives and bioasphalt * 6.3 Albanian deposits

* 7 Health and safety * 8 See also * 9 Notes * 10 References * 11 Sources * 12 External links

TERMINOLOGY

ETYMOLOGY

The word "asphalt" is derived from the late Middle English, in turn from French asphalte, based on Late Latin
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
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
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.

MODERN TERMINOLOGY

In British English
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
Bitumen
mixed with clay was usually called "asphaltum", but the term is less commonly used today.

In Australian English
Australian English
, "bitumen" is often used as the generic term for road surfaces.

In American English
American English
, "asphalt" is equivalent to the British "bitumen". However, "asphalt" is also commonly used as a shortened form of "asphalt concrete " (therefore equivalent to the British "asphalt" or "tarmac").

In Canadian English , the word "bitumen" is used to refer to the vast Canadian deposits of extremely heavy crude oil , while "asphalt" is used for the oil refinery product. Diluted bitumen (diluted with naphtha to make it flow in pipelines) is known as "dilbit " in the Canadian petroleum industry, while bitumen "upgraded " to synthetic crude oil is known as "syncrude", and syncrude blended with bitumen is called "synbit".

"Bitumen" is still the preferred geological term for naturally occurring deposits of the solid or semi-solid form of petroleum. "Bituminous rock" is a form of sandstone impregnated with bitumen. The tar sands of Alberta, Canada are a similar material.

Neither of the terms "asphalt" or "bitumen" should be confused with tar or coal tars .

COMPOSITION

See also: Asphaltene

The components of asphalt include four main classes of compounds:

* Naphthene aromatics (naphthalene ), consisting of partially hydrogenated polycyclic aromatic compounds * Polar aromatics, consisting of high molecular weight phenols and carboxylic acids produced by partial oxidation of the material * Saturated hydrocarbons ; the percentage of saturated compounds in asphalt correlates with its softening point * Asphaltenes, consisting of high molecular weight phenols and heterocyclic compounds

The naphthene aromatics and polar aromatics are typically the majority components. Most natural bitumens also contain organosulfur compounds , resulting in an overall sulfur content of up to 4%. Nickel and va

.