Asphalts analyses

Although distillation and elemental analysis of the fractions provide a good evaluation of the qualities of a crude oil, they are nevertheless insufficient. Indeed, the numerous uses of petroleum demand a detailed molecular analysis. This is true for all distillation fractions, certain crude oils being valued essentially for their light fractions used in motor fuels, others because they make quality lubricating oils and still others because they make excellent base stocks for paving asphalt. 

Analysis of certain papers requires special treatment before they can be disintegrated properly. Papers containing synthetics, tars, asphalt, mbber, viscose, or wet-strength resins must be analyzed individually (see TAPPI T401) (20). Dyes or colors must be removed from highly colored papers before examination. The method of dye removal depends on the type of dye. 

However, for the past 30 years fractional separation has been the basis for most asphalt composition analysis (Fig. 10). The separation methods that have been used divide asphalt into operationally defined fractions. Four types of asphalt separation procedures are now in use ( /) chemical precipitation in which / -pentane separation of asphaltenes is foUowed by chemical precipitation of other fractions with sulfuric acid of increasing concentration (ASTM D2006) (2) solvent fractionation separation of an "asphaltene" fraction by the use of 1-butanol foUowed by dissolution of the 1-butanol solubles in... 

Asphaltenes seem to be relatively constant in composition in residual asphalts, despite the source, as deterrnined by elemental analysis (6). Deterrnination of asphaltenes is relatively standard, and the fractions are termed / -pentane, / -hexane, / -heptane, or naphtha-insoluble, depending upon the precipitant used (5,6,49). After the asphaltenes are removed, resinous fractions are removed from the maltenes-petrolenes usually by adsorption on activated gels or clays. Recovery of the resin fraction by desorbtion is usually nearly quantitative. 

Many attempts have been made to characterize the stabiUty of the colloidal state of asphalt at ordinary temperature on the basis of chemical analysis in generic groups. For example, a colloidal instabiUty index has been defined as the ratio of the sum of the amounts in asphaltenes and flocculants (saturated oils) to the sum of the amounts in peptizers (resins) and solvents (aromatic oils) (66) ... 

Many industries operated throughout the world do not fall into the previous categories. Some of these are universal, such as asphalt batching plants, whereas others are regional, such as bagasse-fired boilers. Each has its own emission and control problems and requires knowledgeable analysis and engineering. Some of the more widely used processes are examined in this section. 

Solvent extraction may also be used to reduce asphaltenes and metals from heavy fractions and residues before using them in catalytic cracking. The organic solvent separates the resids into demetallized oil with lower metal and asphaltene content than the feed, and asphalt with high metal content. Figure 3-2 shows the IFP deasphalting process and Table 3-2 shows the analysis of feed before and after solvent treatment. Solvent extraction is used extensively in the petroleum refining industry. Each process uses its selective solvent, but, the basic principle is the same as above. 

Outdoor lead dust was found to be a more potent contaminant of children s hands than indoor lead dust at day care centers in New Orleans boys, in general, had higher hand lead levels than girls. The conclusions were based on lead analysis of hand wipe samples taken before and after children played outdoors at four different day care centers (a private inner-city site, a private outer-city site, a public inner-city site, and a public outer-city site). The private inner-city site had a severely contaminated outdoor play area with measured soil lead concentrations ranging from 287 to 1,878 mg/kg. The outdoor play area at the public inner-city site, where children exhibited the lowest hand lead measurements of any site in the study, had been completely paved over with concrete or rubberized asphalt and had well-maintained equipment (Viverette et al. 1996). 

The properties of asphalt emulsions (ASTM D977, D2397) allow a variety of uses. As with other petroleum products, sampling is an important precursor to asphalt analysis, and a standard method (ASTM D140) is available that provides guidance for the sampling of asphalts, liquid and semisolid, at point of manufactnre, storage, or delivery. 

Partanen T, Boffetta P Cancer risk in asphalt workers and roofers review and meta-analysis of epidemiologic studies. Am J Ind Med 26(6) 721MO, 1994... 

A characteristic of single sized sands is their comparatively high air void contents which usually exceed 30 percent. Since sulfur s role in SAS mixtures is to fill these air voids without the aid of mechanical densification, both economic and performance considerations would require analysis of the maximum permissible air void content the mixture may possess and still be relatively impermeable to water without sacrificing structural integrity. Figure 4 [15] shows the relationship between air voids content and permeability for both SAS and asphaltic concretes as determined... 

From adsorption analysis data, it is possible to calculate theoretical yields of deoiled wax, asphalt, resins, and solvent extraction yields of waxy raffinate. Nearly 100 different stocks have been so evaluated by California Research Corp. during the past few years and many of these data have been correlated with operations in refinery equipment and with pilot plant operations. 

Another interesting application is transport of highly viscous oil or oil products (e.g. lubricant, asphalt) in rigid or plastic containers transported through pipe by water or low viscosity oil product. A preliminary analysis has shown substantial saving of capital cost and/or operational cost by employing the common carrier transporting system. 

Values of VGC near 0.800 indicate an oil of paraffinic character (see paraffin), values close to 1.00 indicate a preponderance of aromatic structures. Like other indicators of hydrocarbon composition (as opposed to a specific laboratory analysis), VGC should not be indiscriminately applied to residual oils (see bottoms), asphaltic materials, or samples containing appreciable quantities of non-hydrocarbons. See Saybolt Universal Viscosity, specific gravity. 

Of all the materials available for use as a supercritical fluid, CO2 has become the material of choice because of its chemical properties. Instruments have been developed to utilize the principles described to effect extractions of compounds from a variety of sample matrices including asphalt, plant material, and soils (Figure 25.1). The supercritical fluid is pumped through the sample, through a filter or column to a trap where the fluid vaporizes and solvent is added to transfer the analyses to a vial for analysis. More recent instruments combine the supercritical fluid extraction system with a variety of columns and detectors to acquire data from complex samples. 

Soils can have characteristics due to human activity (anthropogenic soils). The forensic examination of soil is therefore not only concerned with the analysis of naturally occurring rocks, minerals, plant, and animal matter it also includes the detection of such manufactured materials as ions from synthetic fertilizers and from different environments (e.g., nitrate, phosphate, sulfate) and environmental artifacts (e.g., lead or objects such as glass, paint chips, asphalt, brick fragments, and cinders). Each of these materials can represent distinct soil characteristics. When unique particles are found in soil evidence, more precise and rapid discrimination can be achieved even if the amount of evidence recovered is microscopic (Sugita and Marumo 2004). For this reason, microscopy is often considered the most useful technique for the detection of such characteristic particles. 

Table I. Elemental Analysis and Properties of Catalytic Cracking Feedstocks (Asphalt Ridge Bitumen)...

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