Bitumen natural asphalt

The bituminous extracts may also be separated into solid and oily materials in a manner similar to the fractionation of petroleum, tar sand bitumen (natural asphalt), refinery (manufactured) asphalts, and petroleum residua (Figure 11.2). As already noted (see also p. 183), the term bitumen is more correctly used for the natural asphalts that occur in various parts of the world and an artifact of the thermal process is often called tar or pitch (Speight, 2007). 

BBTM consists of coarse aggregates of maximum nominal particle size (D) up to 10 mm (or 11.2 mm), fine aggregates 0/2 or 0/4 mm and binder. The binder can be paving grade bitumen. Natural asphalt and additives may also be added. 

The use of petroleum or derived materials, such as asphalt, and the heavier nonvolatile cmde oils is an old art (2). In fact, petroleum utilization has been documented for more than five thousand years. The earliest documented uses occurred in Mesopotamia (ancient Iraq) when it was recognized that the nonvolatile derivatives (bitumen or natural asphalt and manufactured asphalt) could be used for caulking and as an adhesive for jewelry or as a mastic for constmction purposes. There is also documented use of bitumen for medicinal use. 

Large amounts of tar or pitch by-products are produced by industrial processes. The distillation of cmde petroleum (qv) yields a pitch-like residue termed bitumen or asphalt (qv). In the United States, these terms are interchangeable, but in Europe the term asphalt is generally restricted to naturally occurring rock or lake asphalt, whereas the residual product of cmde-od distillation is termed bitumen. Although these are important industrial materials produced in millions of metric tons annually, they are not included herein (see Asphalt Petroleum, products). 

Blends with styrenic block copolymers improve the flexibiUty of bitumens and asphalts. The block copolymer content of these blends is usually less than 20% even as Httie as 3% can make significant differences to the properties of asphalt (qv). The block copolymers make the products more flexible, especially at low temperatures, and increase their softening point. They generally decrease the penetration and reduce the tendency to flow at high service temperatures and they also increase the stiffness, tensile strength, ductility, and elastic recovery of the final products. Melt viscosities at processing temperatures remain relatively low so the materials are still easy to apply. As the polymer concentration is increased to about 5%, an interconnected polymer network is formed. At this point the nature of the mixture changes from an asphalt modified by a polymer to a polymer extended with an asphalt. 

Bitumen, asphalt, and other fossil organic materials such as coal, lignite and peat are found as natural deposits and have practically always been used in arts and handicrafts. Bitumen and asphalt were used in medicines and cosmetics, as pigments, as adhesives and in mummification balms in ancient Egypt [2,159,160]. 

Bitumens occur naturally or are formed as the residue in the distillation of coal tar, petroleum, etc. Industrially, the two most important bitumens are asphalt and coal tar. Asphalt is a brown to black tarlike variety of bitumen that again occurs naturally or is the residue of distillation. Coal tar is the black, thick liquid obtained as the residue from the distillation of bituminous coal. 

An interesting class of styrene-based polymers is ethylene/styrene co-polymers, which have many promising applications as films or foams, as compatibilizers, and as modifiers for bitumens and asphalts. The preparation of these co-polymers by a variety of catalysts has been reported, including both heterogeneous and homogeneous catalysts, but the co-polymers thus obtained typically contained low levels (<4mol%) of styrene incorporation or were heterogeneous in nature. ... 

BITUMEN. Natural flammable substances of a wide range of color, hardness, and volatility, constituted mainly of a mixture of hydrocarbons and essentially free from oxygenated bodies. Petroleums, asphalts, natural mineral waxes, and asphaltites arc considered bitumens. See also Tar Sands. 

Bitumen. Naturally occurring, solid or semisolid, hydrocarbons including asphalt, mineral pitch, petroleum and naphtha. The ASTM designates them as the fraction of hydrocarbons which are sol in CS2. They are rich in C and H and burn with a sooty flame... 

Although it is possible to differentiate between the words bitumen and asphalt in modern use (Speight, 1999a) the occurrence of these words in older texts offers no such possibility. It is significant that the early use of bitumen was in the nature of cement for securing or joining together various objects, and it thus seems likely that the name itself was expressive of this application. 

Tar sand bitumen or natural asphalt may also include vacuum residua (bp >510°C [>950°F])... 

Apart from the natural asphalt, there is also the artificial asphalt , which is a residue of fractional distillation of crude oil (petroleum oil), simply called bitumen or asphalt nowadays. 

In Europe and according to CEN EN 12597 (2000), bitumen is virtually an involatile, adhesive and waterproofing material derived from crude petroleum or present in natural asphalt, which is completely or almost completely soluble in toluene and very viscous or almost solid at ambient temperatures. 

Furthermore, natural asphalt is a relatively hard bitumen found in natural deposits, often mixed with fine or very fine mineral matter, which is virtually solid at 25 C and viscous fluid at 175°C at the same time. 

Rock asphalt, as natural asphalt in liquid-viscous form, was used historically in engineering works but today its use in road works is rare. Rock asphalt nowadays is used only as an additive to petroleum bitumen. Since it is a very hard material, its use is to harden petroleum bitumen. 

Modified bitumen can be used in the whole range of bitumen works, namely, for producing bituminous mixtures (hot to cold), in surface dressings, surface sealing, water insulation and so on. Modified bitumens may be employed directly or in the form of cut-backs or emulsions, or blended with, for example, natural asphalt. 

Natural asphalts such as Trinidad asphalt, rock asphalt or gilsonite are blended with bitumen derived from crude petroleum in order to improve its properties. Since the above additives have very low penetration and very high softening point, the resulting bitumen becomes harder. Since the chemical composition of the natural asphalt is similar to the bitumen from crude petroleum, performing the blending procedure is far easier and homogeneity of the final modified bitumen is ensured. 

In an empirically specified mixture, the grade of bitumen, the type and the grade of modified bitumen or the amount and category of natural asphalt (if used) is always selected and specified. 

The binder of BBTM may be paving grade bitumen, conforming to CEN EN 12591 (2009), or modified bitumen, conforming to CEN EN 14023 (2010). Natural asphalt conforming to CEN EN 13108-4 (2008), Annex B, may also be added. 

Mineral adhesives include silicates and phosphates for high temperature use and naturally derived products such as bitumen and asphalt. 

Bitumens Another important class of oil-based products is bitumens. Bitumen is a generic term defined by ASTM as a class of black or dark-colored (solid, semisolid, or viscous) cementitious substances, natural or manufactured. Bitumens are composed principally of high-molecular-mass hydrocarbons of which asphalt, tars, pitches, and asphaltite are typical. Commercially these are produced from the destructive distillation of coal, crude oils, and other organic matter. Asphalt occurs naturally either in rock or a lake. In the United States the terms bitumen and asphalt are interchangeable, whereas in the United Kingdom asphalt is reserved for the naturally occvuring product and bitumen is the residue from crude oil distillation. It is important to note that the compatibility of various classes of bitumen with other raw materials can vary widely. This can lead, for example, to marked differences in chemical and solvent resistance of the end product. 

Carbonaceous matter (i.e., a disordered carbon) is not transformed into pnre carbon until heat treatment at 2000°C. Pure carbons are never found in nature, with the exception of natural graphite. Nevertheless, natural biomass-derived carbonaceous matter is omnipresent as coals, kerogens, soot, and derivatives such as petroleum, bitumen, or asphalt. It is now more than 60 years that the presence of heteroatoms (H,0,S,N) covalently bound to the carbon skeleton has been swept under the rug, at best implicitly they are known to be responsible for many troubles in the interpretation of carbonization and graphitization data. Because heteroatoms are ignored or neglected, the various calculations do not fit well with experiments. It was thus necessary to add adjustable parameters or include additional phases to obtain agreement between theory and experiments. Additional... 

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