Maltenes are the ''n''- alkane ( pentane or

heptane Heptane or ''n''-heptane is the straight-chain alkane with the chemical formula H3C(CH2)5CH3 or C7H16. When used as a test fuel component in anti-knock test engines, a 100% heptane fuel is the zero point of the octane rating scale (the 100 poin ...

)-soluble molecular components of

asphalt Asphalt, also known as bitumen (, ), is a sticky, black, 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 ...

, which is the residue remaining after

petroleum Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crud ...

refiners remove other useful derivatives such as

gasoline Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organi ...

and

kerosene Kerosene, paraffin, or lamp oil is a combustible hydrocarbon liquid which is derived from petroleum. It is widely used as a fuel in aviation as well as households. Its name derives from el, κηρός (''keros'') meaning "wax", and was regi ...

from crude oil.

Asphaltene Asphaltenes are molecular substances that are found in crude oil, along with resins, aromatic hydrocarbons, and saturates (i.e. saturated hydrocarbons such as alkanes). The word "asphaltene" was coined by Boussingault in 1837 when he noticed tha ...

compounds are the other primary component of asphalt.

Composition

viscous liquids In condensed matter physics and physical chemistry, the terms viscous liquid, supercooled liquid, and glassforming liquid are often used interchangeably to designate liquids that are at the same time highly viscous (see Viscosity of amorphous mater ...

, maltenes consist of heavy, dark-colored asphaltic

resin In polymer chemistry and materials science, resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic compounds. This article focuses on n ...

s, first acidaffins, second acidaffins, and saturates, combined with lighter colored oils. The resins provide the adhesive qualities in asphalts; the oils are the carrier medium for both the maltene resins and the asphaltene compounds. Maltenes are characterized by their lower

molecular weight A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioch ...

and their solubility, in comparison with asphaltenes. Using adsorption

chromatography In chemical analysis, chromatography is a laboratory technique for the separation of a mixture into its components. The mixture is dissolved in a fluid solvent (gas or liquid) called the ''mobile phase'', which carries it through a system ( ...

in the presence of an acid reagent, maltenes can be separated into four fractions: * The polar compounds are highly reactive petroleum resins that act as a colloidal dispersion stabilizer for the asphaltene substrate. * First acidaffins are

aromatic hydrocarbons Aromatic compounds, also known as "mono- and polycyclic aromatic hydrocarbons", are organic compounds containing one or more aromatic rings. The parent member of aromatic compounds is benzene. The word "aromatic" originates from the past groupin ...

, with or without

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

and sulfur. They provide a chemically compatible dispersing agent for peptized asphaltene. * Second acidaffins are straight chain or cyclic unsaturated petro-

hydrocarbons In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or e ...

(aka olefins). They are somewhat oily and somewhat resinous. * Saturates (aka paraffins) are either straight or branch chain

saturated hydrocarbons In organic chemistry, an alkane, or paraffin (a historical trivial name that also has other meanings), is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in whic ...

. They are the true oil component of asphalt binder, and function as the gelling agent for the asphalt compounds.

Analysis

It had long been suspected that asphalt pavement deterioration resulted from chemical reactions of specific asphalt components. In 1959, Fritz Rostler observed: “It is generally recognized that failures of asphalt pavements caused by embrittlement and other changes in physical properties during the aging process are due to chemical reactions of all or some of the asphalt components.” It was Rostler who undertook the necessary research to identify the asphalt components and chemical processes contributing to the aging process. His methodology was to separate the asphalt components by first using sulfuric acid to separate the soluble components, then using an n-pentane solvent to separate the insoluble components. Rostler’s work in the

rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Thailand, Malaysia, an ...

industry led to the development of ASTM Test D-2006-70, which accurately identifies the relationships between the light fraction maltenes, acidaffins and saturates. Although this test has not been updated since 1970, it remains an accurate standard for defining the desirable maltene content distribution in asphalt pavement. ''Rostler Analysis aka ASTM Test D-2006-70'' Where PC represents Polar Compounds, A1 represents First Acidaffins, A2 represents Second Acidaffins, and S represents Saturated Hydrocarbons: Min. Max. Maltene Distribution Ratio D-2006-70 0.3 0.6 (PC + A1) / (S + A2) Rostler determined that the loss of the low-molecular-weight maltene components in asphalt is largely responsible for the cracking and hardening seen in aging pavement. This discovery led to the development of commercial rejuvenators that combine maltene fractions of asphalt with a carrier capable of penetrating asphalt pavements, in order to restore the proper balance of asphalt components.

Geochemistry

The geochemical composition of maltenes varies according to the crude oil source, with any given maltene fraction representing a wide variety of base elements of different concentrations, which may include, for example,

cobalt Cobalt is a chemical element with the symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, p ...

, chromium,

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...

iron Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundanc ...

, molybdenum,

manganese Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...

nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow ...

, strontium, vanadium, or

zinc Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...

.Geochemical implications of trace elements in the saturate, aromatic and resin fractions of crude oil from the Mara and Mara Oeste Fields, Venezuela, Liliana Lopez, ScienceDirect. https://www.researchgate.net/profile/L_Lopez2/publication/244067568_Geochemical_implications_of_trace_elements_and_sulfur_in_the_saturate_aromatic_and_resin_fractions_of_crude_oil_from_the_Mara_and_Mara_Oeste_fields_Venezuela/links/565d8ecf08ae4988a7bc6286/Geochemical-implications-of-trace-elements-and-sulfur-in-the-saturate-aromatic-and-resin-fractions-of-crude-oil-from-the-Mara-and-Mara-Oeste-fields-Venezuela.pdf -implications-of-trace-elements-and-sulfur-in-the-saturate-aromatic-and-resin-fractions-of-crude-oil-from-the-Mara-and-Mara-Oeste-fields-Venezuela.pdf

References

{{reflist Asphalt