Aging Bitumen

In the first case, along with heavy oils, virgin graded bitumen is also added to improve the adhesivity of the aged bitumen. The percentage and type of hydrocarbon used are determined by the chemical industry, which supplies these materials taking into account the properties of the aged bitumen. These materials are also known as bitumen rejuvenators. 

This test is performed in accordance with ASTM D 7175 (2008) or AASHTO T 315 (2012) on unaged and aged bitumen after hardening by RTFO test and PAV test. A brief description of the test is provided in Section 4.8.5.2. 

A bitumen sample is oxidized at high temperature under well defined conditions and its physical characteristics are measured before and after this artificiai ageing process. The method is defined in France as AFNOR T 66-032 and in the USA by ASTM D 2872 (Rolling Thin-Film Oven Test). 

Asphalt (bitumen) also occurs in various oil sand (also called tar sand) deposits which occur widely scattered through the world (17) and the bitumen is available by means of various extraction technologies. A review of the properties and character of the bitumen (18) suggests that, when used as an asphaltic binder, the bitumen compares favorably with specification-grade petroleum asphalts and may have superior aging characteristics and produce more water-resistant paving mixtures than the typical petroleum asphalts. 

For many years atactic polypropylene was an unwanted by-product but today it finds use in a number of markets and is specially made for these purposes rather than being a by-product. In Europe the main use has been in conjuction with bitumen as coating compounds for roofing materials, for sealing strips where it confers improved aging properties and in road construction where it improves the stability of asphalt surfaces. Less important in Europe but more important in USA is its use for paper laminating for which low-viscosity polymers are used, often in conjunction with other resins. Limestone/atactic... 

Bituminous Substances. The distribution of hydrocarbons and other bitumens in some of the Paleozoic rocks of the area is shown in Tables I and II, the latter summarized after Swain (7). The presumed saturated hydrocarbons of the Ordovician, Silurian and Lower Devonian samples are measurably less than in the Middle and Upper Devonian samples. The presumed aromatic hydrocarbons are not as well differentiated. The pyridine-plus-methanol-eluted chromatographic fractions, arbitrarily taken as asphaltic material, also appear, like the aromatic fractions, to be controlled more by local variations than by geologic age. 

With increasing age of the coals the carbon content increases, and the oxygen and methoxyl content decreases in the material free of bitumen as well as in the isolated humic acids (29). 

Many other references to bitumen occur throughout the Greek and Roman empires, and from then to the Middle Ages early scientists (alchemists) frequently alluded to the use of bitumen. In later times, both Christopher Columbus and Sir Walter Raleigh (depending upon the country of origin of the biographer) have been credited with the discovery of the asphalt deposit on the island of Trinidad and apparently used the material to caulk their ships. 

McCaffery M. A., Moldowan J. M., Lipton P. A., Summons R. E., Peters K. E., Jeganathan A., and Watt D. S. (1994b) Paleoenvironmental implications of novel C30 steranes in Precambrian to Cenozoic age petroleum and bitumen. Geochim. Cosmochim. Acta 58, 529-532. 

Analysis of Aged RM-430 Catalyst Samples - Canadian Bitumen Feed. 

The differences found in the yields and compositions of the benzene- and the benzene-methanol soluble bitumens, as well as in the CPI values of the corresponding n-alkane fractions, suggest that standardization of bitumen extraction procedures is necessary if meaningful comparison of the composition of materials isolated from sediments of different ages and origins is to be made. 

Bitumens, were separated by chromatography, urea clathration and 5A molecular sieve occlusion before and after analyses of many of the aliphatic sub-fractions by GC and gas chromatography-mass spectrometry (GC-MS). Experimental details are noted in a previous publication (16) in which the distribution of cyclic alkanes in two lacustrine deposits of Devonian (N.E. Scotland) and Permian (Autun, France) age, (the D and C series samples) were discussed, Chromatographic separation into aliphatic, aromatic and polar compounds of the bitumens extracted from the shales gave the results shown in Table VI. Carbon Preference Indices and pristane/phytane ratios were measured in this work space limitations precluded... 

Tar sand deposits in Venezuela occur in the Officina/Tremblador tar belt that are believed to contain bitumen-impregnated sands of a similar extent to those of Alberta, Canada. The Guanaco Asphalt Lake occurs in deposits that rest on a formation of mid-Pliocene age and is closely associated with the Guanaco crude oil field that produces heavy crude oil from shale and fractured argillite of the Upper Cretaceous group. The tar sands of the Orinoco deposit are located along the southern flanks of the eastern Venezuelan basin. 

Thus, bitumen from a specific deposit is not a uniform material. The chemical and physical (fractional) composition can vary not only with the location and age of the deposit but also with the depth. 

Thermal conductivity, H/C ratio, specific volume and specific heat vary during the chemical evolution of the deposit. Unfortunately, there is very small quantity of data in the literature on thermal conductivity. In fact, what little there is refers to coke or bitumen and provides limited or sometimes contradictory information because of the high dependency on the structure and composition of the solid. More reliable data refer to disordered graphite, similar to an aged deposit, without hydrogen and with a low porosity. The available experimental data on the time evolution of pressure drop and tube metal temperature in pyrolysis coils of ethylene crackers only permit rough estimates of the overall and average thickness and thermal conductivity of the deposit. 

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