Bitumen fluxed

When the viscosity of the bitumen is reduced by the addition of a flux oil (a relatively involatile oil), the bitumen is called fluxed bitumen. Flux oils can be derived from petrochemical, carbochemical or petroleum origin materials, or a mixture of these materials. In this case, the product is called petroleum fluxed bitumen or mineral fluxed bitumen. Typical flux oil is the gas oil of various boiling ranges. 

It is noted that the CEN EN 13808 (2013) standard applies to emulsions of paving bitumen, fluxed bitumen or cut-back bitumen and to emulsions of polymer-modified bitumen, polymer-modified fluxed bitumen or polymer-modified cut-back bitumen, which also includes latex-modified bituminous emulsions. 

The test is suitable for all bituminous binders for surface dressings, such as conventional or polymer-modified bitumen, cut-back bitumens, fluxed bitumen or bituminous emulsions with conventional or modified bitumen. 

The standard NF T 65-003 defines in the same manner three grades of fluxed bitumen. 

Road paving. This includes bitumen, cutbacks and fluxed bitumen as well as emulsions. Each of these products is subject to very special application techniques. This list is completed by the use of poured asphalt, even though this product is better suited to smaller surfaces sidewalks, courts, etc., than to pavements. Since the middle of the 1980 s, air-blown bitumen is no longer used for road construction. 

Flash point (cutbacks, fluxed bitumen). Standards NF T 66-009 and IP 113... 

Timber-preservation creosotes are mainly blends of wash oil, strained anthracene oil, and heavy oil having minor amounts of oils boiling in the 200—250°C range. Coal-tar creosote is also a feedstock for carbon black manufacture (see Carbon, carbon black). Almost any blend of tar oils is suitable for this purpose, but the heavier oils are preferred. Other smaller markets for creosote were for fluxing coal tar, pitch, and bitumen in the manufacture of road binders and for the production of horticultural winter wash oils and disinfectant emulsions. 

Dead Sea, is reported. There is also reference to the use of tar as a mortar when the Tower of Babel was under construction (Genesis 11 3). Another example of the use of pitch (and slime) is given in the story of Moses (Exodus 2 3) where the basket in which he was placed to float in the river was caulked with a derivative. Perhaps the slime was a lower melting bitumen whereas the pitch was a higher melting material the one slime) acting as a flux for the other pitch). 

Air blowing of petroleum residues/flux is the conventional process and is being used for the manufacture of bitumen. Air blowing is done to get the required properties of product and also the pronounce the inherited properties of a required grade. The air blowing of bitumen also referred to as air conversion, provides product with properties that are... 

The packing density of aerated bitumen droplets at the froth interface is a function of droplet size distribution, the flux of material imping-... 

Asphaltic cement can be bitumen, or a mixture of asphalt with bitumen, or flux oils, or pitch, which has cementing qualities suitable for the manufacture of asphalt pavements. 

Bitumens are residues of the vacuum distillation of suitable crude oils (distillation bitumen). Residues of less suitable crudes must be partially oxidized by blowing to achieve the desired technical properties (semi-blown bitumen). Blown bitumens for special purposes can also be produced from vacuum residues. The process is executed by blowing a stream of finely distributed air through the molten bitumen (sometimes reduced in viscosity by addition of flux oil) at temperatures of 250-290 "C. 

It is notable that the dispersion medium, as well as the petroleum resins of the blown bitumen are more aliphatic in character than those components of the distillation bitumens. This may be caused by the composition of the flux oils which were added. The asphaltenes of both types of bitumen display similar aromacity (Table 4-54) ... 

Evaporation of the distillation bitumens and their colloidal components first starts at temperatures 200 °C (71 %) or 259 °C (75 %). Since thin-layer evaporation takes place in the thermobalance, and the evaporated parts of the sample are immediately removed by the gas flow, these temperatures are lower than the real start temperatures of an equilibrium evaporation (for example distillation according to Engler DIN 51 751 or ASTM D 285-62). The corresponding start temperatures for an equilibrium evaporation should be more than 400 °C. The evaporation start temperatures for bitumen, dispersion medium, and petroleum resins are lower in the case of blown bitumens, influenced by the flux oils which are added in order to facilitate the blowing process. Some of the index numbers of the thermogravimetry may be correlated with consistency data, and with analysis data (see chapters 4.3.2.1.1 and 4.3.2.1.2). Other values show only a small... 

The very low value for the dispersion medium of the blown bitumens indicate that a distillation process has taken place, rather than cracking. The influence of low boiling flux oils is evident. 

Some overlapping of the evaporation and pyrolysis reactions was observed, due to the content of low boiling flux oils, especially in the experiments with separated components of the colloid system. In order to avoid such overlapping as much as possible and to simulate the technical conditions of the crack processes, further investigations on bitumens and their colloid components were carried out in a hydrocarbon atmosphere (methane) at 10 bar pressure. 

One cannot be certain about the beginning of oxidation of the blown bitumens, their dispersion medium, or their petroleum resins, because this type of bitumen contains relative low boiling flux oils. There are only small, statistically insignificant, differences between the means of the DTG maximum temperatures of the blown bitumens, their dispersion medium and their petroleum resins in air and in argon. Thermogravimetry cannot determine whether evaporation or oxidation takes place. Use of a simultaneous thermal analyzer might prove whether the reaction is exo- or endothermic. 

The peak maximum temperatures of the blown bitumens are not so uniform and therefore the calculation of means is not worth while. Some of the blown bitumens, their dispersion medium and their petroleum resins demonstrate peak maxima both in the distillation and in the pyrolysis range because of the content of low boiling flux oils. The activation energies computed for the distillation range are equal to the enthalpies of vaporization, as shown by experiments on model substances. 

Major uses for creosotes have been as a timber preservative, as fluxing oils for pitch and bitumen, and in the manufacture of lampblack and carbon black. However, the use of creosote as a timber preservative has recently come under close scrutiny, as have many other ill-defined products of coal processing. Issues related to the seepage of such complex chemical mixtures into the surrounding environment have brought an awareness of the potential environmental and health hazards related to the use of such chemicals. Stringent testing is now required before such chemicals can be used. 

Cut-back bitumen constitutes bitumen whose viscosity has been reduced by the addition of a relatively volatile flux. In case the volatile flux is derived from petroleum, the material is called petroleum cut-back bitumen. Typical petroleum-derived fluxes used are white spirit and kerosene. Petroleum cut-back bitumens are almost exclusively used, and, for simplicity, they are called cut-back bitumens (or asphalts). 

Additionally, flux oils can be derived from plant-based (vegetal) products. In this case, the product is called vegetal fluxed bitumen. 

The viscosity of the bitumen is significantly reduced that cut-back bitumens or fluxed bitumens are considered as liquids and require far less heating energy during application in comparison to solid (at ambient temperatures) bitumen. 

Cut-back and fluxed bituminous binders are suitable for use in the construction and maintenance of roads, airfields and other paved areas. The bitumen used may be paving grade bitumen (in most cases) or by addition of polymer. 

However, cut-back bitumens and, to a lesser extent, fluxed bitumens used to be extensively used in the past, mainly for the production of open or semi-dense graded bituminous mixtures. Today, their use is limited to prime coating, to in situ production of cold/semi-warm bituminous mixtures particularly in remote areas away from a hot mix plant and to the production of ready-mixed bituminous mix for repairing-filling works (potholes, utility cuts, local depressions, etc.). 

Cut-back bitumens, as well as the fluxed bitumens, are designated by the viscosity and setting ability or viscosity and curing time. They may also be designated by the bitumen type (paving grade or with addition of polymer). 

According to the European standard, there are three classes (2, 3 and 4) of cut-back bitumens and fluxed bitumen with respect to low and medium viscosity and three classes of high viscosity (5, 6 and 7). 

Hence, using Table 3.9, the characterisation Fm 4 B 6 indicates a medium-viscosity cutback or flux oil material based on paving grade bitumen that contains relatively volatile petroleum-based flux of which more than 55% distils at 225 C. 

Apart from the technical properties/requirements of the cut-back bitumens and fluxed bitumens, the standard also defines the technical properties of the stabilised (recovered) bitumen. The properties/requirements, which are specified for stabilised bitumens with penetration below 330 dmm, are such as presented in Table 3.10. There is also a similar table for softer bitumens with penetration higher than 330 dmm (see CEN EN 15322 2013). 

Source Reproduced from CEN EN 15322, Bitumen and bituminous binders - Framework for specifying cut-back and fluxed... 

According to the abovementioned data, the usage of petroleum cut-back bitumens, as well as the fluxed bitumens, has been limited, and in some countries, their usage has been prohibited (Asphalt Institute MS-19 Chipperfield and Leonard 1976 Nikolaides and Oikonomou 1987 Transportation Research Board No. 30 1975). 

According to CEN EN 13808 (2013), a combination of letters and numbers is used to describe a bitumen emulsion. The cationic emulsions are designated by the letter C two numbers indicating the nominal binder content one or up to three letters such as B (for paving grade bitumen), P (for polymer-modified bitumen) and F (for bitumen with more than 3% [m/m] flux oil) and a number indicating the class of breaking behaviour. 

Additionally, the designation of bitumen emulsion C 69 BF 3 means that the emulsion is cationic, its nominal binder content is 69%, produced from bitumen and contains more than 3% flux, and its breaking value belongs to class 3. 

The pendulum (Vialit) test, according to CEN EN 13588 (2008), determines the cohesion of any bituminous binder (pure, modified or fluxed). Cohesion is one of the measures of the performance of the bituminous binder, particularly modified bitumen or bitumen recovered from bitumen emulsion. It is important to use binders that have a sufficient level of cohesion according to the level of traffic to be supported. 

CEN EN 12846-2. 2011. Bitumen and bituminous binders - Determination of efflux time by the efflux viscometer - Part 2 Cut-back and fluxed bituminous binders. Brussels CEN. 

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